Mechanisms of Grain Growth Inhibition

The grain growth inhibitors primarily influence WC grain growth through the following approaches:

Solute Drag Effect

Principle:grain growth Inhibitor elements (e.g., V, Cr) dissolve into the WC or Co phase, adsorb at WC/Co phase boundaries or WC/WC grain boundaries, hindering atomic diffusion and grain boundary migration.

Elemental Solid Solution

Inhibitors such as VC and Cr?C? decompose during sintering, with V and Cr atoms dissolving into the WC lattice or Co binder phase.

Example: V substitutes W sites in WC (forming (V,W)C solid solution), while Cr dissolves into the Co phase (forming (Co,Cr) solid solution).

Grain Boundary Segregation

Solute atoms (e.g., V, Cr) enrich at WC grain boundaries or WC/Co interfaces, forming a “solute atmosphere.”

These segregated atoms pin grain boundaries, increasing the energy barrier for migration.

Drag on Grain Boundary Movement

When grain boundaries attempt to migrate, solute atoms must move along, but their slower diffusion rate impedes boundary motion.

Analogous to “viscous drag,” this suppresses WC grain coalescence and growth.

Applicable grain growth Inhibitors: VC, Cr?C? (primarily rely on solute drag).

Second-Phase Pinning Effect (Zener Pinning)

Principle: grain growth inhibitors form nanoscale carbide particles (e.g., (V,W)C, (Cr,W)C) that physically obstruct WC grain growth at boundaries.

Nanoparticle Precipitation

During sintering, decomposed VC or Cr?C? reprecipitate as nanoscale carbides (e.g., 5–50 nm (V,W)C particles), typically located at WC/WC or WC/Co interfaces.

Grain Boundary Pinning

Migrating boundaries must overcome the restraint of these nanoparticles, requiring additional energy.

According to the Zener equation, pinning force (F?) correlates with particle volume fraction (f) and size (r). Finer, denser particles yield stronger inhibition.

Suppression of WC Dissolution-Reprecipitation

Nanoparticles hinder WC dissolution in liquid Co and redeposition, reducing Ostwald ripening (“large grains consuming small ones”).

Applicable grain growth Inhibitors: VC (strongest pinning), Cr?C? (moderate), TaC/NbC (weaker).

Common Grain Growth Inhibitors and Their Characteristics

Selection and Optimization of grain growth Inhibitors

Ranking of Inhibition Effectiveness

VC > Cr?C? > TaC ≈ NbC

Key Influencing Factors

Sintering Temperature and Time:

High temperatures or prolonged sintering may weaken inhibitor effectiveness (e.g., VC particle coarsening).

Co Content

Alloys with higher Co require greater grain growth inhibitor content (due to enhanced WC dissolution in liquid Co).

Carbon Balance

Inhibitors may consume free carbon, necessitating carbon potential adjustment to avoid η-phase formation (e.g., Co?W?C).

Detailed Industrial Application Cases of Cemented Cacbua Grain Growth Inhibitors

Grain growth inhibitors (e.g., VC, Cr?C?, TaC) are widely used in the cemented carbide industry, primarily in cutting tools, mining tools, and wear-resistant components. The selection of different inhibitors directly affects the alloy’s hardness, toughness, wear resistance, and high-temperature stability. Below is an in-depth analysis of several typical application cases.

Ultra-Fine Grain Cemented Carbide Cutting Tools (VC + Cr?C? Composite Inhibition)

Application Background

Requirement: High-speed cutting and precision machining (e.g., automotive engine blocks, aerospace titanium alloys) demand tools with both high hardness (>90 HRA) and chipping resistance.

Issue

Conventional WC-Co alloys have coarse grains (1–3 μm), exhibiting high hardness but low toughness, leading to edge chipping.

Solution

Ultra-fine grain cemented carbide (grain size 0.2–0.5 μm) achieved through VC (0.3–0.5 wt%) + Cr?C? (0.5–1.0 wt%) composite addition.

Inhibition Mechanism

VC: Nano-sized (V,W)C particles pin WC grain boundaries (Zener pinning), suppressing grain coalescence.

Cr?C?: Cr dissolves into the Co phase, reducing WC dissolution rate (solute drag) while enhancing oxidation resistance.

Representative Products

Sandvik GC4325: For titanium alloy machining, using VC+Cr?C? inhibition (0.3 μm grains).

Kennametal KCS10B: For stainless steel finishing, incorporating nano-VC.

Mining Cemented Carbide Drill Bits (TaC/NbC High-Temperature Inhibition)

Application Background

Requirement: Oil drill bits and tunnel boring machine cutters operate under high temperatures (>800°C) and impact loads, requiring thermal fatigue resistance and wear resistance.

Issue

Conventional WC-Co alloys experience rapid grain growth at high temperatures, reducing strength.

Solution

TaC (1–3 wt%) or NbC (1–2 wt%) addition to leverage their high-temperature stability for grain growth suppression.

Inhibition Mechanism

TaC/NbC: Form (Ta,W)C or (Nb,W)C solid solutions at high temperatures, pinning grain boundaries (Zener effect) and reducing boundary mobility.

Synergy with Co binder: Ta/Nb dissolution into Co increases liquid Co viscosity, slowing WC dissolution-reprecipitation.

Representative Products

Atlas Copco Button Bits: TaC-containing drill bits for granite drilling.

Sumitomo Electric DX Series: Oil drilling alloys with NbC for thermal stability.

Wear-Resistant Sealing Rings (Cr?C? Inhibition + Rare Earth Optimization)

Application Background

Requirement: Mechanical seals and bearing sleeves require high wear resistance + corrosion resistance (e.g., chemical pumps, seawater environments).

Issue

WC-Co suffers from selective corrosion of the Co phase in corrosive media, causing WC grain detachment.

Solution

Cr?C? (1.0–1.5 wt%) + rare earth oxides (Y?O? 0.1–0.3 wt%) composite addition.

Inhibition Mechanism:

Cr?C?: Forms (Cr,W)C particles to refine grains while improving corrosion resistance via Cr dissolution in Co.

Y?O?: Rare earth elements segregate at grain boundaries, purifying interfaces and strengthening boundary cohesion.

Representative Products

Mitsubishi Materials EX Series: Chemical pump seals with Cr?C? + rare earth modification.

Oerlikon Durit CR: Corrosion-resistant alloys with Cr?C?.

PCB Micro-Drills (Ultra-Fine VC + Sintering Process Optimization)

Application Background

Requirement: PCB micro-drills (diameter 0.1–0.3 mm) demand ultra-high precision (roundness <1 μm) and fatigue resistance.

Issue

Grain coarsening causes drill edge blunting and fracture during drilling.

Solution

Ultra-fine VC (0.2–0.4 wt%) + low-temperature sintering (1350°C, vs. conventional 1450°C).

Inhibition Mechanism

Nano-VC: Prepared via high-energy ball milling (<50 nm particles) for enhanced pinning.

Low-temperature sintering: Reduces Ostwald ripening time, preserving inhibitor efficacy.

Representative Products

Toshiba Tungaloy DLC-Coated Micro-Drills: Nano-VC inhibition technology.

TaeguTec PCB Drill: Optimized for high-layer PCBs.

S? k?t lu?n

Grain growth inhibitors in cemented carbides control grain size through solute drag and second-phase pinning mechanisms. Their selection must be optimized based on material composition, sintering processes, and performance requirements. Future trends favor nano-composite inhibitors and multi-component synergistic regulation to further enhance comprehensive material properties.

At present, the regions in China that are most active in the recycling and regeneration of waste cemented carbide include Jinan City in Shandong Province, Qinghe County in Hebei Province, Mudanjiang City in Heilongjiang Province, and Zhuzhou City and Changsha City in Hunan Province.

Economic Benefits of Recycling Waste Carbide

Tungsten is the main component of cemented carbide, accounting for almost 50% of the total tungsten usage in its production, with China’s share being around 40%. Relevant data indicate that the demand for cemented carbide in various countries will rise significantly from the end of this century to the beginning of the next. It is estimated that by 2000, the demand could reach 40,000 tons, about 1.5 times the current production. However, tungsten is a rare element, with a crustal abundance of only 1×10?%, and the currently exploitable tungsten is only sufficient for 50 years.

Although China is a major producer of tungsten, both its reserves and recoverable quantities are showing a decreasing trend. Therefore, the rational utilization and recycling of tungsten resources should be placed on our agenda as an urgent issue to be seriously studied. Assuming that China’s recycling rate of waste alloy increases from 10% to 20%, it would mean an annual increase of several hundred tons of tungsten production. This would require the provision of several thousand tons of tungsten concentrate (containing 65% WO?) as raw material, equivalent to the tungsten content of 220,000 tons of raw ore (with a grade of 0.5% WO?). Thus, vigorously recycling cemented carbide is of great significance for the rational utilization and protection of existing tungsten resources.

Another major component of cemented carbide is cobalt. Due to the lack of cobalt resources in China, a large amount of cobalt needs to be imported annually to meet production needs. At the current level, recycling several hundred tons of cemented carbide in China each year could recover several tens of tons of cobalt, thereby saving a significant amount of foreign exchange for?our?country.

Processing Techniques of Recycling Waste Carbide

It is reported that there are currently about 30 different processing techniques used for the recycling of waste cemented carbide. Below is a brief introduction to several of the most commonly used and effective techniques in production.

Nitrate Fusion Method

This method involves melting waste cemented carbide together with nitrate at temperatures ranging from 900°C to 1200°C, resulting in the formation of soluble sodium tungstate. The reaction equation is as follows:

At this stage, the cooled melt is crushed and then leached with water to obtain a sodium tungstate solution and cobalt residue, which are then processed through normal procedures.

The advantages and disadvantages of this method are as follows: it has a large processing capacity and a wide range of applications, but it suffers from low recovery rates, high costs, poor working conditions, and significant pollution.

High-Temperature Oxidation Method

This method involves placing the cemented carbide in a temperature range of 700–950°C to oxidize it in air or oxygen. During this process, oxygen reacts with the alloy through the following chemical reaction:

The oxidized product is a brittle substance that, when treated with sodium hydroxide or a mixture of sodium hydroxide and sodium carbonate in a high-pressure leaching device, yields a sodium tungstate solution. The cobalt remaining in the residue is separated out according to conventional processes.

Phosphoric acid leaching method

Immerse the waste carbide?in a phosphoric acid solution and leach at a temperature of 50-60°C. Phosphoric acid reacts with cobalt in the carbide?to form cobalt phosphate, which enters the solution and separates from tungsten carbide. The advantages and disadvantages are: since phosphoric acid is a weak acid, the problem of equipment corrosion is easily solved, making it suitable for processing various waste carbides. However, the recovered tungsten carbide has a high oxygen content, and the subsequent process flow is long.

Zinc melting method

React waste carbides with zinc at a temperature close to 900°C. The cobalt in the alloy forms a zinc-cobalt low-melting-point alloy, causing the tungsten carbide in the waste alloy to lose the cobalt’s bonding effect and become loose. Then, vacuum distillation is used to evaporate and recover the metal zinc.

After the zinc melting process, the waste carbide?consists of layers of tungsten carbide and cobalt layers arranged in a multi-layered and interlocking pattern. It is a loose bulk material, which, after crushing, becomes a recycled carbide?mixture.

The advantages and disadvantages of the zinc melting method are: the process and equipment are relatively simple, the actual recovery rate is high, the production process causes less pollution, and the recovered mixture can be used directly for the production of tungsten products. However, this method consumes a lot of energy, with an electricity consumption of 4000-10000 degrees for processing 1 ton of waste carbide, and the recovered material contains a small amount of zinc, which has a certain impact on product quality.

Sodium sulfate fusion method

This method involves reacting waste carbides with sodium sulfate at a temperature of 900-1000°C to form a molten tungstic acid. After cooling, it is then leached with hot water to obtain a sodium tungstate solution and cobalt slag. The reaction equation is as follows: (The specific reaction equation is not provided in the original text, so it cannot be translated here.)

Its advantages and disadvantages are: wide adaptability and large production capacity. The drawback is that sulfur dioxide gas is emitted during the production process.

Electrolysis fusion method of recycling waste carbide

This method involves placing the waste carbide?in an electrolytic cell as the anode, nickel plate as the cathode, and dilute hydrochloric acid as the electrolyte. After electrolysis, the cobalt in the carbide?enters the solution in the form of COCl?. The washed and ground WC can be directly used to produce alloys. This method yields pure products, is highly efficient, has simple equipment, and is easy to operate. It is particularly suitable for processing with high cobalt content and has high value for promotion and application.

Cold embrittlement method

The cold embrittlement method involves crushing the waste carbide?coarsely, removing impurities, and then using a high-speed air stream to inject the coarsely crushed carbide?into a vacuum chamber equipped with a carbide?paddle, followed by further crushing to obtain a mixture.

This method has a wide range of processing and treatment, and the production process does not cause environmental pollution, but the equipment cost is relatively high.

According to reports, the zinc dissolution method is widely used for the recycling of waste carbides in China at the current stage. Overseas, the most economical method is considered to be a combination of the zinc dissolution method and the cold embrittlement method. In summary, there are many methods for recycling and processing waste carbides, each with its own pros and cons. When selecting a method in practice, a comprehensive analysis and comparison should be conducted based on the type of waste carbide, the size of the production scale, equipment capacity, technical level, and the source of raw and auxiliary materials, to choose an advanced, reasonable, and economically significant process for production practice.

Technical and Economic Preliminary Evaluation of Several Process Methods for Recycling Waste Carbides

As mentioned earlier, the zinc fusion method, electrolysis dissolution method, and mechanical crushing method have all become the main industrial methods for recycling and regenerating waste carbides. The recycled and regenerated powders can be used to produce carbides through conventional processes, which undoubtedly promotes the full utilization of non-ferrous metal resources such as tungsten and cobalt, saves energy, reduces manufacturing costs, promotes the development of small and medium-sized enterprises, and provides employment for the unemployed. Among them, the powder produced by the electrolysis dissolution method is particularly good in quality with low impurity content, low energy consumption, moderate processing costs, and good economic benefits (the selling price of WC powder is only 60% to 70% of the conventional product). It is one of the main methods being vigorously developed in many regions of our country.

Tóm l??c

It should be pointed out that the recycling and regeneration of waste carbides is a new venture and an emerging industrial sector in the field of carbides, which should be affirmed and supported. At the same time, great attention must be paid to product quality in the work of recycling and utilizing waste carbides, especially since most enterprises are still at a relatively low level of manual workshop production. Many enterprises often focus only on economic benefits while neglecting the control and testing of the recycling process and powder quality, which is incorrect. In the future, enterprises engaged in this kind of production should continuously improve and enhance the recycling process and product quality, strengthen the recognition of the importance of “product quality is the life of the enterprise,” and must not be careless. Otherwise, it will be difficult to maintain a firm foothold in the fierce market competition for a long time, let alone continue to develop and grow.

1. phát tri?n quy trình x? ly ??ng l?nh

X? ly ??ng l?nh th??ng s? d?ng ph??ng pháp làm mát b?ng nit? l?ng, có th? làm mát ph?i xu?ng d??i -190oC. C?u trúc vi m? c?a v?t li?u ???c x? ly thay ??i ? nhi?t ?? th?p và m?t s? tính ch?t ???c c?i thi?n. X? ly ??ng l?nh l?n ??u tiên ???c Liên X? c? ?? xu?t vào n?m 1939. Ph?i ??n nh?ng n?m 1960, Hoa K? m?i áp d?ng c?ng ngh? x? ly ??ng l?nh vào ngành c?ng nghi?p và b?t ??u s? d?ng ch? y?u trong l?nh v?c hàng kh?ng. Vào nh?ng n?m 1970, nó m? r?ng sang l?nh v?c s?n xu?t máy móc.

Theo các ph??ng pháp làm l?nh khác nhau, nó có th? ???c chia thành ph??ng pháp l?ng và ph??ng pháp khí. Ph??ng pháp l?ng có ngh?a là v?t li?u ho?c ph?i ???c nhúng tr?c ti?p vào nit? l?ng ?? làm ngu?i ph?i ??n nhi?t ?? nit? l?ng, và ph?i ???c gi? ? nhi?t ?? này trong m?t th?i gian nh?t ??nh, sau ?ó ???c ??a ra ngoài và nung nóng ??n m?t nhi?t ?? nh?t ??nh. . R?t khó ?? ki?m soát t?c ?? t?ng và gi?m nhi?t ?? theo cách này, ?i?u này có tác ??ng nhi?t l?n ??n ph?i và th??ng ???c cho là có kh? n?ng gay h? h?ng cho ph?i. Thi?t b? ??ng l?nh t??ng ??i ??n gi?n, ch?ng h?n nh? bình nit? l?ng.

2. ph??ng pháp x? ly ??ng l?nhgas

Nguyên ly khí là làm mát b?ng nhi?t ?n khí hóa(chǎn) c?a nit? l?ng (kho?ng 199,54kJ/kg) và s? h?p th? nhi?t c?a nit? ? nhi?t ?? th?p. Ph??ng pháp khí có th? làm cho nhi?t ?? ??ng l?nh ??t t?i - 190oC, do ?ó nit? ??ng l?nh có th? ti?p xúc v?i v?t li?u. Th?ng qua trao ??i nhi?t ??i l?u, nit? có th? bay h?i trong h?p ??ng l?nh sau khi ???c ??y ra kh?i vòi phun. Ph?i có th? ???c làm mát b?ng nhi?t ?n c?a quá trình khí hóa(chǎn) và s? h?p th? nhi?t c?a nit? ??ng l?nh. B?ng cách ki?m soát ??u vào c?a nit? l?ng ?? ki?m soát t?c ?? làm mát, nhi?t ?? x? ly ??ng l?nh có th? ???c ?i?u ch?nh t? ??ng và ki?m soát chính xác, hi?u ?ng s?c nhi?t nh? nên kh? n?ng b? n?t c?ng nh?.

Hi?n nay, ph??ng pháp khí ???c các nhà nghiên c?u c?ng nh?n r?ng r?i trong ?ng d?ng c?a nó, và thi?t b? làm mát c?a nó ch? y?u là h?p l?nh có th? l?p trình v?i nhi?t ?? có th? ki?m soát ???c. X? ly b?ng ph??ng pháp ??ng l?nh có th? c?i thi?n ?áng k? tu?i th?, kh? n?ng ch?ng mài mòn và ?? ?n ??nh kích th??c c?a kim lo?i ?en, kim lo?i màu, h?p kim kim lo?i và các v?t li?u khác, mang l?i l?i ích kinh t? ?áng k? và tri?n v?ng th? tr??ng.

C?ng ngh? ??ng l?nh c?a cacbua xi m?ng l?n ??u tiên ???c báo cáo vào nh?ng n?m 1980 và 1990. C?ng ngh? c? khí c?a Nh?t B?n n?m 1981 và C?a hàng máy hi?n ??i c?a Hoa K? vào n?m 1992 báo cáo r?ng hi?u su?t c?a cacbua xi m?ng ?? ???c c?i thi?n ?áng k? sau khi x? ly ??ng l?nh. T? nh?ng n?m 1970, c?ng vi?c nghiên c?u v? x? ly ??ng l?nh ? n??c ngoài ?? có k?t qu?. Liên X? c?, Hoa K?, Nh?t B?n và các n??c khác ?? s? d?ng thành c?ng ph??ng pháp x? ly ??ng l?nh ?? c?i thi?n tu?i th? c?a d?ng c? và khu?n, kh? n?ng ch?ng mài mòn c?a ph?i và ?n ??nh kích th??c.

3. t?ng c??ng c? ch? ?i?u tr? ??ng l?nh

Gia c? pha kim lo?i.

Co trong cacbua liên k?t có c?u trúc tinh th? fcc pha α (fcc) và c?u trúc tinh th? l?c giác ?óng gói kín ε Pha (hcp). ε- T? s? Co α- Co có h? s? ma sát nh? và ch?u mài mòn m?nh. Trên 417 ℃ α N?ng l??ng t? do c?a pha th?p nên t?n t?i d?ng pha Co α. D??i 417 ℃ ε N?ng l??ng t? do c?a pha th?p, pha ?n ??nh ? nhi?t ?? cao α Chuy?n pha sang pha có n?ng l??ng t? do th?p ε Pha. Tuy nhiên, do các h?t WC và α S? t?n t?i c?a các d? nguyên t? trong dung d?ch r?n trong pha có h?n ch? l?n h?n ??i v?i s? chuy?n pha, làm cho α → ε Khi ?i?n tr? thay ??i pha t?ng và nhi?t ?? gi?m xu?ng d??i 417 ℃ α thì pha kh?ng th? chuy?n hoàn toàn. thành ε Pha. X? ly ??ng l?nh có th? làm t?ng ?áng k? α Và ε S? chênh l?ch n?ng l??ng t? do hai pha, do ?ó làm t?ng ??ng l?c c?a s? thay ??i pha ε Bi?n s? thay ??i pha. ??i v?i cacbua liên k?t sau khi x? ly ??ng l?nh, m?t s? nguyên t? hòa tan trong Co k?t t?a ? d?ng h?p ch?t do gi?m ?? hòa tan, có th? làm t?ng pha c?ng trong ma tr?n Co, c?n tr? s? di chuy?n l?ch v? trí và ?óng vai trò t?ng c??ng pha th? hai. v?t r?t nh?.

T?ng c??ng ?ng su?t d? b? m?t.

Nghiên c?u sau khi x? ly ??ng l?nh cho th?y ?ng su?t nén d? trên b? m?t t?ng lên. Nhi?u nhà nghiên c?u tin r?ng m?t giá tr? nh?t ??nh c?a ?ng su?t nén d? trong l?p b? m?t có th? c?i thi?n ?áng k? tu?i th? c?a nó. Trong quá trình làm ngu?i c?a cacbua xi m?ng sau khi thiêu k?t, pha liên k?t Co ch?u ?ng su?t kéo, và các h?t WC ph?i ch?u ?ng su?t nén. ?ng su?t kéo có tác h?i l?n ??i v?i Co. Do ?ó, m?t s? nhà nghiên c?u tin r?ng s? gia t?ng ?ng su?t nén b? m?t do làm ngu?i sau s? làm ch?m l?i ho?c bù ??p m?t ph?n ?ng su?t kéo t?o ra b?i giai ?o?n liên k?t trong quá trình làm ngu?i sau khi nung k?t, ho?c th?m chí ?i?u ch?nh nó ?? ?ng su?t nén, gi?m s? phát sinh các v?t n?t nh?.

Các c? ch? t?ng c??ng khác

Ng??i ta tin r?ng η Các h?t pha cùng v?i các h?t WC làm cho ma tr?n tr? nên ch?t ch? và ch?c ch?n h?n, và do η S? hình thành c?a pha tiêu th? Co trong ma tr?n. S? gi?m hàm l??ng Co trong pha liên k?t làm t?ng ?? d?n nhi?t t?ng th? c?a v?t li?u, và s? gia t?ng kích th??c h?t cacbua và s? k? nhau c?ng làm t?ng ?? d?n nhi?t c?a ch?t n?n. Do s? gia t?ng c?a ?? d?n nhi?t, s? t?n nhi?t c?a các ??u dao và khu?n d?p nhanh h?n; C?i thi?n kh? n?ng ch?ng mài mòn và ?? c?ng nhi?t ?? cao c?a d?ng c? và khu?n. Nh?ng ng??i khác tin r?ng sau khi x? ly ??ng l?nh, do Co co l?i và c? ??c, vai trò v?ng ch?c c?a Co trong vi?c gi? các h?t WC ???c t?ng c??ng. Các nhà v?t ly cho r?ng vi?c làm l?nh sau ?? làm thay ??i c?u trúc c?a các nguyên t? và phan t? c?a kim lo?i.

4.M?t tr??ng h?p YG20 Cold Heading Die v?i Cryogenic Treatment

Các b??c v?n hành c?a x? ly ??ng l?nh ván khu?n tr? thép YG20:

(1) ??a khu?n ngu?i thiêu k?t vào lò x? ly ??ng l?nh;

(2) Kh?i ??ng lò tích h?p ? ??ng l?nh, m? nit? l?ng, gi?m xu?ng -60oC ? t?c ?? nh?t ??nh và gi? nhi?t ?? trong 1h;

(3) Gi?m xu?ng -120oC ? t?c ?? nh?t ??nh và gi? nhi?t ?? trong 2 gi?;

(4) Gi?m nhi?t ?? xu?ng -190oC ? t?c ?? làm mát nh?t ??nh và gi? nhi?t ?? trong 4-8h;

(5) Sau khi b?o qu?n nhi?t, nhi?t ?? s? ???c t?ng lên 180 ℃ theo 0,5 ℃ / phút trong 4 gi?

(6) Sau khi thi?t b? ch??ng trình hoàn thành, thi?t b? s? t? ??ng t?t ngu?n và làm mát t? nhiên ??n nhi?t ?? phòng.

K?t lu?n: ??u khu?n l?nh YG20 kh?ng qua x? ly ??ng l?nh và sau khi x? ly ??ng l?nh là ??u ngu?i Φ 3.8 Thanh vít b?ng thép cacbon, k?t qu? cho th?y tu?i th? c?a khu?n sau khi x? ly ??ng l?nh dài h?n 15% so v?i khu?n kh?ng qua x? ly ??ng l?nh .

Có th? th?y r?ng so v?i tr??c khi x? ly ??ng l?nh, coban l?p ph??ng tam m?t (fcc) trong YG20 sau khi x? ly ??ng l?nh gi?m ?áng k?, ε- S? gia t?ng r? r?t c?a Co (hcp) c?ng là ly do c?i thi?n kh? n?ng ch?ng mài mòn và ??c tính toàn di?n c?a cacbua xi m?ng.

5. H?n ch? c?a quá trình x? ly ??ng l?nh

K?t qu? ?ng d?ng th?c t? c?a m?t c?ng ty s?n xu?t d?ng c? và khu?n ?úc ? Hoa K? cho th?y tu?i th? c?a mi?ng chèn cacbua xi m?ng sau khi x? ly t?ng lên 2 ~ 8 l?n, trong khi chu k? thay b?ng c?a khu?n kéo day cacbua xi m?ng sau khi x? ly kéo dài t? vài tu?n ??n vài tháng. Trong nh?ng n?m 1990, nghiên c?u trong n??c v? c?ng ngh? ??ng l?nh c?a cacbua xi m?ng ?? ???c th?c hi?n và ?? ??t ???c m?t s? k?t qu? nghiên c?u nh?t ??nh.

Nhìn chung, nghiên c?u v? c?ng ngh? x? ly ??ng l?nh cacbua xi m?ng hi?n nay ít ???c phát tri?n và ch?a có h? th?ng, các k?t lu?n thu ???c c?ng kh?ng th?ng nh?t, c?n ???c các nhà nghiên c?u tìm hi?u sau h?n. Theo d? li?u nghiên c?u hi?n có, x? ly ??ng l?nh ch? y?u c?i thi?n kh? n?ng ch?ng mài mòn và tu?i th? c?a cacbua xi m?ng, nh?ng kh?ng có ?nh h??ng r? ràng ??n các tính ch?t v?t ly.

X? ly bán kính c?nh là m?t quá trình kh?ng th? thi?u sau khi mài m?n các d?ng c? CNC và tr??c khi ph?. M?c ?ích là làm cho l??i c?t m?n và m??t, ??ng th?i kéo dài tu?i th? c?a d?ng c?. Có 9 ph??ng pháp x? ly bán kính c?nh c?a d?ng c? CNC ???c Meetyou gi?i thi?u. Chúng ta h?y làm quen v?i nó.

X? ly bán kính c?nh c?a d?ng c? c?t c?a trung tam gia c?ng ?? c?p ??n quá trình san b?ng, ?ánh bóng và làm m? các d?ng c? c?t, bao g?m th? ??ng c?nh, ?ánh bóng r?nh lo?i b? phoi và ?ánh bóng l?p ph?.

1. Kh? n?ng ch?ng mài mòn v?t ly c?a d?ng c?

Trong quá trình c?t, b? m?t d?ng c? s? b? ph?i tiêu hao d?n và l??i c?t d? b? bi?n d?ng d?o d??i nhi?t ?? cao và áp su?t cao. Vi?c x? ly th? ??ng c?a d?ng c? có th? giúp c?i thi?n ?? c?ng c?a d?ng c? và tránh m?t hi?u su?t c?t s?m c?a d?ng c?.

2. Duy trì ?? m?n c?a ph?i

Các g? trên l??i c?t c?a d?ng c? s? gay mòn d?ng c? và b? m?t ph?i ???c gia c?ng s? tr? nên nhám. Sau khi x? ly th? ??ng, l??i c?t c?a d?ng c? s? tr? nên r?t m?n, hi?n t??ng x?p c?nh s? gi?m ?i t??ng ?ng và ?? bóng b? m?t c?a ph?i c?ng s? ???c c?i thi?n.

3. Lo?i b? phoi r?nh ti?n l?i

?ánh bóng r?nh d?ng c? có th? c?i thi?n ch?t l??ng b? m?t và hi?u su?t lo?i b? phoi. B? m?t r?nh càng m?n thì kh? n?ng lo?i b? phoi càng t?t và có th? ??t ???c ???ng c?t ?n ??nh h?n.

Sau khi th? ??ng và ?ánh bóng, các d?ng c? c?a máy c?ng c? CNC s? ?? l?i nhi?u l? nh? trên b? m?t. Nh?ng l? này có th? h?p th? nhi?u ch?t l?ng c?t h?n trong quá trình gia c?ng, ?i?u này s? làm gi?m ?áng k? nhi?t sinh ra trong quá trình c?t và c?i thi?n ?áng k? t?c ?? c?t.

9 lo?i ph??ng pháp x? ly bán kính c?nh

Ph??ng pháp bán kính c?nh bánh mài

?ay là c?ng ngh? th? ??ng s?m nh?t và ???c s? d?ng r?ng r?i nh?t.

Ph??ng pháp bán kính c?nh bàn ch?i nylon

Ph??ng pháp ph? bi?n là ph? m?i tr??ng mài mòn g?m các h?t m?n lên bánh xe bàn ch?i ho?c ??a bàn ch?i b?ng v?t li?u nylon và di chuy?n l?i dao c?t th?ng qua chuy?n ??ng quay t?c ?? cao c?a bàn ch?i.

Ph??ng pháp phun cát

nó ???c chia thành phun cát kh? và phun cát ??t. Nó c?ng là m?t ph??ng pháp ph? bi?n ?? x? ly bán kính c?nh. So v?i ph??ng pháp ch?i nylon, quá trình này ??t ???c ?? ??ng nh?t cao h?n c?a các c?nh.

Ph??ng pháp khu?y x? ly bán kính c?nh

Ph??ng pháp này là ??t toàn b? d?ng c? vào thùng mài mòn tr??c khi x? ly và ??nh v? ?? sau c?a d?ng c? th?ng qua c?m bi?n laser ?? ??m b?o ch?t l??ng x? ly. ?? ??c c?a l??i c?a quá trình này c?ng cao h?n so v?i ph??ng pháp dùng ch?i nylon.

Gia c?ng bán kính c?nh c? ?i?n hóa(chǎn)

?ay là m?t quá trình t?ng h?p k?t h?p gi?a gia c?ng ?i?n hóa(chǎn) và mài c? h?c. ??u tiên, lo?i b? ba via b?ng ?i?n phan, sau ?ó là mài c? h?c ?? lo?i b? màng oxit.

Ph??ng pháp laser: là c?ng ngh? th? ??ng ???c phát tri?n trên c? s? c?ng ngh? ph? laser. Nó có th? t?o ra nhi?t ?? cao trên b? m?t l??i dao b?ng tia laser, làm tan ch?y m?t s? v?t li?u và ??t ???c hi?u qu? th? ??ng hóa(chǎn) l??i dao.

Ph??ng pháp x? ly bán kính c?nh rung

 thi?t b? x? ly chính bao g?m bàn rung và bàn làm vi?c. L??i dao ???c ??t trong m?t thùng ch?a ???c n?i v?i than rung. Thùng ch?a ??y các h?t mài mòn. Các h?t mài mòn và l??i dao va ch?m liên t?c ?? lo?i b? các v?t li?u còn sót l?i trên l??i c?t th?ng qua va ch?m ?? ??t ???c s? th? ??ng c?a c?nh.

Ph??ng pháp mài mòn t? tính

?ay là quá trình x? ly bán kính c?nh, áp d?ng t? tr??ng theo h??ng vu?ng góc v?i tr?c c?a b? m?t hình tr? c?a ph?i và thêm l?c mài mòn t? tính gi?a các c?c S và N c?a t? tr??ng. Ch?t mài mòn t? tính s? ???c h?p ph? trên c?c t? và b? m?t ph?i và s? ???c b? trí thành m?t “bàn ch?i mài mòn” linh ho?t d?c theo h??ng c?a ???ng s?c t?. Máy c?t quay và rung d?c tr?c cùng lúc ?? lo?i b? kim lo?i và các g? trên b? m?t ph?i.

C?ng ngh? tia n??c mài mòn vi m?: c?ng ngh? x? ly m?i và than thi?n v?i m?i tr??ng, t?o thành tia n?ng l??ng cao r?n-l?ng th?ng qua vi?c ?i?u khi?n b? ?i?u áp và ???ng kính vòi phun, ??ng th?i th?c hi?n x? ly th? ??ng b?ng va ch?m t?c ?? cao và l?p ?i l?p l?i trên ph?i.

Etching is a technology that uses chemical strong acid corrosion, mechanical polishing or electrochemical electrolysis to treat the surface of objects. In addition to enhancing aesthetics, it also increases the added value of objects. From traditional metal processing to high-tech semiconductor manufacturing, they are all within the scope of application of etching technology.

Metal etching is a technology to remove metal materials through chemical reaction or physical impact. Metal etching technology can be divided into wet etching and dry etching. Metal etching consists of a series of chemical processes. Different etchants have different corrosion characteristics and strength for different metal materials.

Metal etching, also known as photochemical etching, refers to the removal of the protective film of the metal etching area after exposure, plate making, development and contact with the chemical solution in the process of metal etching, so as to achieve dissolution corrosion, formation of bumps, or hollowing out. It was first used to manufacture printed concave convex plates such as copper plate and zinc plate. It is widely used to reduce the weight of instrument panel or process thin workpieces such as nameplate. Through the continuous improvement of technology and process equipment, etching technology has been applied to aviation, machinery, chemical industry and semiconductor manufacturing processes for the processing of precision metal etching products of electronic thin parts.

Types of etching technology

Wet etching:

Wet etching is to immerse the wafer into a suitable chemical solution or spray the chemical solution onto the wafer for quenching, and remove the atoms on the surface of the film through the chemical reaction between the solution and the etched object, so as to achieve the purpose of etching During wet etching, the reactants in the solution first diffuse through the stagnant boundary layer, and then reach the wafer surface to produce various products through chemical reactions. The products of etching chemical reaction are liquid or gas phase products, which are then diffused through the boundary layer and dissolved in the main solution. Wet etching will not only etch in the vertical direction, but also have the effect of horizontal etching.

Dry etching:

Dry etching is usually one of plasma etching or chemical etching. Due to different etching effects, the physical atoms of ions in the plasma, the chemical reaction of active free radicals and the surface atoms of devices (wafers), or the combination of the two, include the following contents:

physical etching: sputtering etching, ion beam etching

chemical etching: plasma etching

physicochemical composite etching: reactive ion etching (RIE)

Dry etching is a kind of anisotropic etching, which has good directivity, but the selectivity is worse than wet etching. In plasma etching, plasma is a partially dissociated gas, and gas molecules are dissociated into electrons, ions and other substances with high chemical activity. The biggest advantage of dry etching is “anisotropic etching”. However, the selectivity of dry etching is lower than that of wet etching. This is because the etching mechanism of dry etching is physical interaction; Therefore, the impact of ions can remove not only the etching film, but also the photoresist mask.

Etching process

According to the type of metal, the etching process will be different, but the general etching process is as follows: metal etching plate → cleaning and degreasing → water washing → drying → film coating or silk screen printing ink → drying → exposure drawing → development → water washing and drying → etching → film stripping → drying → inspection → finished product packaging.

1. Cleaning process before metal etching:

The process before etching stainless steel or other metals is cleaning treatment, which is mainly used to remove dirt, dust, oil stains, etc. on the material surface. The cleaning process is the key to ensure that the subsequent film or screen printing ink has good adhesion to the metal surface. Therefore, the oil stain and oxide film on the metal etching surface must be completely removed. Degreasing shall be determined according to the oil stain of the workpiece. It is best to degrease the silk screen printing ink before electric degreasing to ensure the degreasing effect. In addition to the oxide film, the best etching solution shall be selected according to the type of metal and film thickness to ensure surface cleanliness. It must be dry before screen printing. If there is moisture.

2. Paste dry film or silk screen photosensitive adhesive layer:

According to the actual product material, thickness and the exact width of the figure, it is determined to use dry film or wet film silk screen printing. For products with different thicknesses, factors such as the etching processing time required for product graphics should be considered when applying the photosensitive layer. It can make a thicker or thinner photosensitive adhesive layer with good coverage performance and high definition of patterns produced by metal etching.

3. Drying:

After the completion of film or roll screen printing ink, the photosensitive adhesive layer needs to be thoroughly dried to prepare for the exposure process. At the same time, ensure that the surface is clean and free of adhesion, impurities, etc.

4. Exposure:

This process is an important process of metal etching, and the exposure energy will be considered according to the thickness and accuracy of the product material. This is also the embodiment of the technical ability of etching enterprises. The exposure process determines whether the etching can ensure better dimensional control accuracy and other requirements.

5. Development:

After the photosensitive adhesive layer on the surface of the metal etching plate is exposed, the pattern adhesive layer is cured after exposure. Then, the unwanted part of the pattern, that is, the part that needs corrosion, is exposed. The development process also determines whether the final size of the product can meet the requirements. This process will completely remove the unnecessary photosensitive adhesive layer on the product.

6. Etching or etching process:

After the product prefabrication process is completed, the chemical solution will be etched. This process determines whether the final product is qualified. This process involves etching solution concentration, temperature, pressure, speed and other parameters. The quality of the product needs to be determined by these parameters.

7. Removal:

The surface of the etched product is still covered with a layer of photosensitive adhesive, and the photosensitive adhesive layer on the surface of the etched product needs to be removed. Because the photosensitive adhesive layer is acidic, it is mostly expanded by acid-base neutralization method. After overflow cleaning and ultrasonic cleaning, remove the photosensitive adhesive layer on the surface to prevent photosensitive adhesive residue.

8. Test:

After the film is taken, the following is testing, packaging, and the final product is confirmed whether it meets its specifications.

Precautions in etching process

reduce side corrosion and protruding edges and improve metal etching processing coefficient: generally, the longer the printed board is in the metal etching solution, the more serious the side etching is. Undercutting seriously affects the accuracy of printed wire, and serious undercutting will not make thin wire. When the undercut and edge decrease, the etching coefficient increases. The high etching coefficient indicates that the thin line can be maintained and the etched line is close to the size of the original image. Whether the plating resist is tin lead alloy, tin, tin nickel alloy or nickel, the excessively protruding edge will lead to short circuit of the conductor. Because the protruding edge is easy to break, an electric bridge is formed between two points of the conductor.

improve the consistency of etching processing rate between plates: in continuous plate etching, the more consistent the metal etching processing rate, the more uniform etching plate can be obtained. In order to maintain the best etching state in the pre etching process, it is necessary to select an etching solution that is easy to regenerate and compensate and easy to control the etching rate. Select technologies and equipment that can provide constant operating conditions and automatically control various solution parameters. It can be realized by controlling the amount of copper dissolved, pH value, solution concentration, temperature, uniformity of solution flow, etc.

improve the uniformity of the metal etching processing speed of the whole plate surface: the etching uniformity of the upper and lower sides of the plate and each part of the plate surface is determined by the uniformity of the flow rate of the metal etching solution on the plate surface. In the etching process, the etching rates of the upper and lower plates are often inconsistent. The etching rate of the lower plate surface is higher than that of the upper plate surface. Due to the accumulation of solution on the surface of the upper plate, the etching reaction is weakened. The uneven etching of the upper and lower plates can be solved by adjusting the injection pressure of the upper and lower nozzles. The spray system and the oscillating nozzles can further improve the uniformity of the whole surface by making the spray pressure of the center and edge of the plate different.

Advantages of etching process

Because the metal etching process is etched by chemical solution.

maintain high consistency with raw materials. It does not change the properties, stress, hardness, tensile strength, yield strength and ductility of the material. The base processing process is etched in the equipment in an atomized state, and there is no obvious pressure on the surface.

no burrs. In the process of product processing, there is no pressing force in the whole process, and there will be no crimping, bumping and pressing points.

it can cooperate with the post process stamping to complete the personalized molding action of the product. The hanging point method can be used for full plate electroplating, bonding, electrophoresis, blackening, etc., which is more cost-effective.

it can also cope with miniaturization and diversification, short cycle and low cost.

Application field of etching processing

consumer electronics

filtration and separation technology

Aerospace

medical equipment

precision machinery

car

high end crafts

Cacbua xi m?ng là m?t lo?i cacbua xi m?ng ???c ch? t?o t? quá trình luy?n kim b?t t? h?p ch?t c?ng c?a kim lo?i ch?u l?a và kim lo?i liên k?t. B?i vì ?? c?ng và s?c m?nh t?t c?a nó, nó ???c s? d?ng r?ng r?i trong nhi?u l?nh v?c. V?i yêu c?u v? hi?u su?t nhi?t ?? cao và kh? n?ng ch?ng ?n mòn c?a v?t li?u cacbua xi m?ng ngày càng cao, hi?u su?t c?a v?t li?u cacbua xi m?ng hi?n t?i khó ?áp ?ng yêu c?u s? d?ng. Trong 30 n?m qua, nhi?u h?c gi? ?? th?c hi?n nghiên c?u th? nghi?m các h?p ch?t d?a trên WC và thu ???c m?t lo?t k?t qu? nghiên c?u.

Kim lo?i WC

WC-Co

V?t li?u xi m?ng ???c s? d?ng r?ng r?i trong cacbua vonfram là coban. H? th?ng WC Co ?? ???c nghiên c?u r?ng r?i. Vi?c b? sung CO làm cho WC có ?? ?m và ?? bám dính t?t. Ngoài ra, nh? trong Hình 13.2, vi?c b? sung CO c?ng có th? c?i thi?n ?áng k? s?c m?nh và ?? d?o dai.

Hình 13.3 Máy vi tính ?i?n t? tán x? ng??c c?a b?t WC Co cho th?y c?u trúc bên ngoài và m?t c?t ngang: (a), (b) F8; (c), (d) M8; và (E), (f) C8.

?ng ?? th?c hi?n hình ?nh ?i?n t? tán x? ng??c c?a b?t F8, M8 và C8 và các ph?n ???c ?ánh bóng c?a chúng. Nó ?? ???c quan sát th?y r?ng t?t c? các lo?i b?t có hình d?ng hình c?u ?i?n hình. B?t F8 cho th?y s? tích t? dày ??c c?a các cacbua m?n, trong khi b?t M8 và C8 cho th?y c?u trúc tích l?y t??ng ??i l?ng l?o v?i m?t s? l? chan l?ng. Trên ph?n ?ánh bóng, t?t c? các m?u cho th?y hi?n t??ng tán x? r? ràng, và ?? c?ng và kh? n?ng ch?ng mài mòn t? l? ngh?ch v?i hàm l??ng coban. ?? c?ng Vickers (HV) thay ??i t? 1500 ??n 2000 HV30, và ?? b?n g?y dao ??ng t? 7 ??n 15 MPa M1 / 2. S? thay ??i ?áng k? này là m?t ch?c n?ng c?a thành ph?n cacbua, c?u trúc vi m? và ?? tinh khi?t hóa(chǎn) h?c.

Nói chung, kích th??c h?t càng nh? thì ?? c?ng càng cao và kh? n?ng ch?ng mài mòn càng t?t. T? l? th? tích c?a CO càng cao thì ?? b?n g?y càng cao, nh?ng ?? c?ng và kh? n?ng ch?ng mài mòn càng th?p (Jia et al., 2007). Do ?ó, ?? có ???c hi?u su?t t?t h?n, thay vào ?ó, kh?ng th? tránh kh?i vi?c s? d?ng các v?t li?u xi m?ng khác.

M?t khác, vì nh?ng ly do trên, nó kh?ng khoa h?c trong chi?n l??c và d? ?nh h??ng ??n xu h??ng giá c?. Ngoài ra, s? k?t h?p gi?a WC và b?i ??ng là ?áng lo ng?i vì chúng gay ch?t ng??i nhi?u h?n b?t k? vi?c s? d?ng nào.

WC-Ni

Niken r? h?n và d? ki?m h?n coban. Nó có m?t tài s?n c?ng r?n t?t. Nó có th? ???c s? d?ng ?? c?i thi?n hi?u su?t ?n mòn / oxy hóa(chǎn), ?? b?n nhi?t ?? cao và ch?ng mài mòn trong m?i tr??ng kh?c nghi?t. So v?i h?p kim WC Co, ?? d?o c?a v?t li?u th?p h?n. B?i vì niken hòa tan t?t trong WC, nó ???c s? d?ng làm ch?t k?t dính cho ch?t n?n WC, d?n ??n liên k?t m?nh m? gi?a chúng.

WC-Ag

Vi?c b? sung Ag làm cho WC tr? thành m?t lo?i v?t li?u ch?ng h? quang. D??i tác ??ng c?a dòng quá t?i, WC th??ng ???c t?i trong các thi?t b? chuy?n m?ch, ?i?u này có th? ???c quy cho ?i?n tr? ti?p xúc ?i?n (RC) n?i ti?ng sau này. ?i?u ?áng nói là ?i?n tr? su?t c?a h?n h?p WC Ag gi?m khi t?ng hàm l??ng Ag và ?? c?ng gi?m khi t?ng hàm l??ng Ag, ?i?u này là do s? khác bi?t l?n gi?a ?? c?ng c?a WC và Ag. Ngoài ra, các h?t WC th? có s?c ?? kháng ti?p xúc r?t th?p và ?n ??nh.

Hình 13.4 cho th?y ?i?n tr? ti?p xúc ?i?n trung bình (RC) ???c t?o ra b?i c?ng t?c

Chu k? 11e50 v?i hàm l??ng b?c và kích th??c h?t WC khác nhau, b?i vì RC c?a h?u h?t các v?t li?u ???c quan sát là ?n ??nh sau 10 chu k? chuy?n ??i. ?i?n tr? ti?p xúc c?a b?c n?m trong kho?ng t? 50-55 wt% (t? l? th? tích 60% và 64.6%) trong WC v?i kích th??c h?t là 4 mm và t? 55-60 wt% (t? l? th? tích 64.6% và 69%) trong WC v?i kích th??c h?t 0,8 và 1,5 mm. Do ?ó, ?i?u này xác ??nh thành ph?n ban ??u c?a kho?n ??u t?, trong ?ó ma tr?n Ag ???c liên k?t hoàn toàn. ??i v?i các thành ph?n c? ??nh, s? gi?m ?i?n tr? ti?p xúc gi?a kích th??c h?t WC 1,5 ??n 4 mm ?? ???c quan sát, c?ng ?ánh d?u ng??ng th?m.

WC-Re

Các nhà khoa h?c ?ang s? d?ng cacbua vonfram ?? t?ng c??ng rheni ?? có ???c hi?u su?t t?t h?n WC Co, b?i vì RE có th? mang l?i ?? c?ng ? nhi?t ?? cao và s? k?t h?p t?t

Hình 13.4 t? l? c?a ?i?n tr? ti?p xúc ?i?n trung bình ? hàm l??ng Ag khác nhau và kích th??c h?t WC so v?i ?i?n tr? ti?p xúc c?a ch?t n?n WC trong chu k? 11 ??n 50 là co ho?c Ni. Theo ??c ?i?m c?u trúc vi m? c?a WC coere (hàm l??ng RE 20%), ???c m? t? r?ng WC coere gi? l?i trong CO và ti?p t?c hình thành c?u trúc HCP, do ?ó c?i thi?n ?? c?ng c?a h?p kim. Các nhà nghiên c?u c?ng t?ng c??ng l?i trong WC Ni và tìm th?y nh?ng suy lu?n t??ng t?. Do ?? c?ng cao nh?t và ?? b?n g?p ??i c?a WC Co, h?p kim ???c s? d?ng ?? s?n xu?t các b? ph?n c?ng c? c?nh tranh. Khi ép l?nh WC và b?t Re theo quy trình ép nóng ???c c?p b?ng sáng ch?, h?n 2400 kg / mm ~ 2 c?a HV ?? ???c quan sát (so v?i 1700 kg / mm ~ 2 ??i v?i WC-Co)

WC ??i x?ng

WC-FeAl

Trong vài th?p k? qua, các h?p ch?t intermetallic nh? ch?t k?t dính g?m ?? thu hút s? chú y c?a m?i ng??i. S?t aluminide có kh? n?ng ch?ng oxy hóa(chǎn) và ch?ng ?n mòn tuy?t v?i, ??c tính th?p, ?? c?ng cao, ch?ng mài mòn t?t, ?n ??nh nhi?t ?? cao và ?? ?m t?t. Nó là nhi?t ??ng phù h?p cho WC nh? ch?t k?t dính. ?? c?ng và ?? b?n g?y c?a WC FeAl và WC Co v? c? b?n là gi?ng nhau. ?? c?ng và kh? n?ng ch?ng mòn c?a h?p kim WC Co t??ng t? nh? h?p kim WC Co th?ng th??ng. Có th? xem xét r?ng n?u kích th??c h?t có th? ???c t?i ?u hóa(chǎn), có th? thay th? C?ng ty WC truy?n th?ng ???ng cong phan b? kích th??c h?t c?a b?t h?n h?p WC FeAl ???c ?i?u ch? b?ng các quá trình nghi?n và / ho?c s?y bóng khác nhau ???c th? hi?n trong Hình 13,5. Ba ???ng cong trong hình 13,5 có phan b? l??ng kim. Trong hình 13,5, ??nh trái c?a kích th??c h?t nh? h?n t??ng ?ng v?i ??nh trái c?a h?t WC ??n. Giá tr? ??nh chính xác c?a kích th??c h?t l?n h?n t??ng ?ng v?i giá tr? c?c ??i c?a các m?nh FeAl ch?a m?t s? h?t WC. Khi ??nh chính xác di chuy?n, ??nh trái kh?ng ph? thu?c vào quá trình nghi?n và / ho?c s?y. ??nh chính xác c?a b?t DR (ethanol ?? kh? n??c làm dung m?i ?? làm kh? nhanh) chuy?n sang ??nh t??ng ?ng c?a hai lo?i b?t còn l?i.

Hình 13,5 Phan b? kích th??c h?t c?a b?t h?n h?p WC-FeAl ???c ?i?u ch? t? các quy trình b?t khác nhau.

WC-g?m

WC-MgO

V?t li?u composite Wc-mgo ?? ???c s? d?ng r?ng r?i do vi?c b? sung các h?t MgO trong ma tr?n WC, ít ?nh h??ng ??n ?? c?ng và c?i thi?n ?áng k? ?? d?o dai c?a v?t li?u. ?? c?ng t? l? ngh?ch v?i ?? b?n, nh?ng trong tr??ng h?p c?a h?p kim này, ?? b?n có ???c khi ?? m?t ?? c?ng r?t nh?. Thêm m?t l??ng nh? VC, Cr3C2 và các ch?t ?c ch? t?ng tr??ng h?t khác vào v?t li?u ???c nghiên c?u kh?ng ch? có th? ki?m soát s? t?ng tr??ng c?a h?t trong quá trình thiêu k?t mà còn c?i thi?n tính ch?t c? h?c c?a v?t li?u.

WC-Al2O3

? ?ay ph?i ?? c?p r?ng Al 2 O 3 ???c s? d?ng làm v?t li?u gia c? cho WC và ng??c l?i, vì các tính ch?t c? ly tuy?t v?i c?a chúng.

Nhi?t ?? thiêu k?t và th?i gian gi? có ?nh h??ng ?áng k? ??n c?u trúc vi m? và tính ch?t c? h?c c?a h?n h?p wc-40vol% Al2O3. V?i s? gia t?ng c?a nhi?t ?? thiêu k?t và th?i gian gi?, m?t ?? t??ng ??i và kích th??c h?t t?ng lên. ??ng th?i, các giá tr? c?a áp l?c cao và ?? b?n g?y x??ng t?ng tr??c và sau ?ó gi?m. C?u trúc vi m? c?a ???ng n?t cho th?y s? t?n t?i c?a c?u n?t và ?? l?ch v?t n?t. Trong v?t li?u t?ng h?p wc-40vol% Al 2O 3, c? ch? làm c?ng chính là t?o ra các v?t n?t th? c?p và bên. M?t nghiên c?u khác cho th?y HV kho?ng 20e25gpa và ?? b?n g?y là 5e6mpa.m1 / 2.

Hình 13.6 cho th?y xu h??ng bi?n ??i c?a ?? c?ng, ?? b?n g?y và ?? b?n g?y ngang v?i hàm l??ng alumina. C?n l?u y r?ng nh?ng giá tr? này khá khác bi?t v?i nh?ng giá tr? ???c báo cáo (Mao et al., 2015). WC nguyên ch?t có ?? c?ng cao nh?t và ?? b?n g?y th?p nh?t. Vi?c b? sung Al2O3 giúp c?i thi?n ?? b?n g?y, nh?ng ?? c?ng c?a alumina tinh khi?t th?p h?n so v?i WC nguyên ch?t và ?? c?ng c?a composite wc-al2o3 gi?m. Các k?t qu? khác nhau trong Hình 13.6 cho th?y các tính ch?t c? h?c kh?ng ch? ph? thu?c vào hàm l??ng alumina, mà còn ph? thu?c vào quá trình s?n xu?t và c?p ch?t n?n khác nhau. 

WC mài mòn

WC cBN

Do CBN có ?? c?ng tuy?t v?i, ?? ?n ??nh nhi?t và ho?t ??ng ph?n ?ng v?i s?t, vi?c thêm CBN vào WC Co có th? c?i thi?n kh? n?ng ch?ng mài mòn, ?? c?ng và tính ch?t c? h?c c?a v?t li?u. Khi CBN ???c t?ng c??ng vào ma tr?n WC, ?? bám dính m?nh s? ???c t?o ra. Ngoài ra, ?? b?n g?y t?t h?n có th? ??t ???c b?ng cách làm l?ch v?t n?t ho?c b?c c?u c?a các h?t CBN. Hai tr? ng?i chính trong quá trình b? sung CBN là chuy?n ??i t? CBN sang hBN và liên k?t c?ng hóa(chǎn) tr? m?nh gi?a B và N, d?n ??n kh? n?ng thiêu k?t th?p c?a CBN và cacbua xi m?ng.

Kim c??ng WC

WC kim c??ng có ?? b?n g?y tuy?t v?i, ch?ng n?t t?ng tr??ng và ch?ng ph?n x?. V?t li?u này ch? có th? ???c s?n xu?t trong ?i?u ki?n nhi?t ??ng ?? ng?n kim c??ng bi?n thành than chì. Th?ng qua nhi?u nghiên c?u ?? c?i thi?n hi?u su?t c?a v?t li?u này, chúng t?i có th? t?o ra kho?ng cách chi phí r?t l?n, r?t c?n thi?t.

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Gi?i thi?u Thép ???c làm ngu?i b?ng cách nung nóng thép ??n nhi?t ?? cao h?n nhi?t ?? t?i h?n Ac3 (thép hypo-eutectoid) ho?c Ac1 (thép hypereutectoid), gi? nó trong m?t kho?ng th?i gian ?? austenit hóa(chǎn) toàn b? ho?c m?t ph?n, sau ?ó ???c làm ngu?i ? nhi?t ?? nhi?t ?? l?n h?n t?c ?? làm ngu?i t?i h?n Làm l?nh nhanh xu?ng d??i Ms (ho?c Ms g?n ??ng nhi?t) quá trình x? ly nhi?t martensitic (ho?c bainite). X? ly dung d?ch các v?t li?u nh? h?p kim nh?m, h?p kim ??ng, h?p kim titan, kính c??ng l?c, v.v., ho?c các quá trình x? ly nhi?t v?i làm l?nh nhanh c?ng th??ng ???c g?i là quá trình t?i. Làm ngu?i là m?t quá trình x? ly nhi?t ph? bi?n, ch? y?u ???c s? d?ng ?? t?ng ?? c?ng c?a v?t li?u. Th?ng th??ng t? m?i tr??ng làm ngu?i, có th? ???c chia thành làm ngu?i b?ng n??c, làm ngu?i d?u, làm ngu?i h?u c?. V?i s? phát tri?n c?a khoa h?c và c?ng ngh?, m?t s? quy trình d?p t?t m?i ?? xu?t hi?n.1 Ph??ng pháp d?p t?t làm mát b?ng kh?ng khí áp su?t cao Các ph?i trong dòng khí tr? m?nh ???c làm mát nhanh chóng và ??ng ??u, ?? ng?n ch?n quá trình oxy hóa(chǎn) b? m?t, tránh n?t, gi?m bi?n d?ng, ?? ??m b?o r?ng ?? c?ng c?n thi?t, ch? y?u ?? làm ngu?i thép c?ng c?. C?ng ngh? này g?n ?ay ?? phát tri?n nhanh chóng và ph?m vi ?ng d?ng c?ng ?? ???c m? r?ng ?áng k?. Hi?n t?i, c?ng ngh? làm ngu?i khí chan kh?ng ?? phát tri?n nhanh chóng và làm mát khí t?c ?? dòng ch?y cao áp su?t am (<1 × 105 Pa), sau ?ó là làm mát khí và áp su?t cao (1 × 105 ~ 4 × 105 Pa) 10 × 105 Pa) kh?ng khí -làm mát, làm mát b?ng kh?ng khí áp su?t c?c cao (10 × 105 ~ 20 × 105 Pa) và các c?ng ngh? m?i khác kh?ng ch? giúp t?ng c??ng ?áng k? kh? n?ng làm ngu?i chan kh?ng c?a làm mát b?ng kh?ng khí mà còn làm ngu?i ?? sáng b? m?t ph?i t?t, bi?n d?ng nh?, nh?ng c?ng có hi?u qu? cao, ti?t ki?m n?ng l??ng, kh?ng gay ? nhi?m, v.v. Vi?c s? d?ng ph??ng pháp làm ngu?i b?ng khí làm mát b?ng khí áp su?t cao chan kh?ng là quá trình làm ngu?i và t?i luy?n v?t li?u, dung d?ch, quá trình l?o hóa(chǎn), cacbon hóa(chǎn) ion và th?m cacbon c?a thép kh?ng g? và các h?p kim ??c bi?t, c?ng nh? quá trình thiêu k?t chan kh?ng, làm mát và làm ngu?i sau khi hàn. V?i quá trình làm ngu?i b?ng nit? áp su?t cao 6 × 105 Pa, t?i ch? có th? ???c làm mát r?i, thép t?c ?? cao (W6Mo5Cr4V2) có th? ???c làm c?ng ??n 70 ~ 100 mm, thép ch?t gia c?ng h?p kim cao lên ??n 25 ~ 100 mm, vàng l?nh thép khu?n làm vi?c (ch?ng h?n nh? Cr12) lên ??n 80 ~ 100 mm. Khi ???c làm ngu?i b?ng nit? áp su?t cao 10 × 10 5 Pa, t?i ???c làm mát có th? r?t m?nh, làm t?ng m?t ?? t?i kho?ng 30% lên 40% so v?i làm mát b?ng 6 × 10 5 Pa. Khi ???c làm ngu?i b?ng nit? c?c cao 20 × 10 5 Pa. nit? áp su?t ho?c h?n h?p helium và nit?, các t?i ???c làm mát s? dày ??c và có th? ???c bó l?i v?i nhau. M?t ?? làm mát b?ng nit? 6 × 105 Pa 80% ??n 150%, có th? làm mát t?t c? thép t?c ?? cao, thép h?p kim cao, thép c?ng c? gia c?ng nóng và thép crom Cr13% và nhi?u lo?i thép t?i d?u h?p kim h?n, ch?ng h?n nh? thép 9Mn2V kích th??c l?n h?n. Lò t?i hai bu?ng làm mát b?ng kh?ng khí v?i các bu?ng làm mát riêng bi?t có kh? n?ng làm mát t?t h?n so v?i các lo?i lò m?t bu?ng cùng lo?i. Lò ??i bu?ng làm mát b?ng nit? 2 × 105 Pa có hi?u qu? làm mát t??ng t? nh? lò bu?ng ??n 4 × 105 Pa. Tuy nhiên, chi phí v?n hành, chi phí b?o trì th?p. Khi ngành c?ng nghi?p v?t li?u c? b?n c?a Trung Qu?c (than chì, molypden, v.v.) và các thành ph?n ph? tr? (??ng c?) và các c?p ?? khác ???c c?i thi?n. Do ?ó, ?? c?i thi?n vi?c ch?m sóc chan kh?ng áp su?t cao m?t bu?ng 6 × 105 Pa trong khi duy trì s? phát tri?n c?a lò làm ngu?i áp su?t bu?ng kép và làm mát b?ng kh?ng khí áp su?t cao phù h?p h?n v?i ?i?u ki?n qu?c gia c?a Trung Qu?c. Hình 1 kh?ng khí áp su?t cao- lò chan kh?ng làm mát2 ph??ng pháp làm ngu?i m?nh Ph??ng pháp làm ngu?i th?ng th??ng th??ng là làm mát b?ng d?u, n??c ho?c dung d?ch polyme, và quy t?c làm ngu?i m?nh b?ng n??c ho?c n??c mu?i n?ng ?? th?p. Làm ngu?i m?nh ???c ??c tr?ng b?i kh? n?ng làm ngu?i c?c nhanh, mà kh?ng ph?i lo l?ng v? s? bi?n d?ng quá m?c c?a thép và n?t. Quá trình làm ngu?i th?ng th??ng ??n nhi?t ?? làm ngu?i, s?c c?ng b? m?t thép ho?c tr?ng thái ?ng su?t th?p, và làm ngu?i m?nh ? gi?a quá trình làm mát, tam ph?i v?n ? tr?ng thái nóng ?? ng?ng làm mát, do ?ó hình thành ?ng su?t nén b? m?t. Trong ?i?u ki?n làm ngu?i kh?c nghi?t, austenite siêu l?nh trên b? m?t thép ph?i ch?u ?ng su?t nén 1200 MPa khi t?c ?? làm mát c?a vùng bi?n ??i martensitic cao h?n 30 ℃ / s, do ?ó c??ng ?? n?ng su?t c?a thép sau khi làm ngu?i ???c t?ng ít nh?t là 25%.Nguyên ly: Thép t? quá trình t?i ? nhi?t ?? austenit hóa(chǎn), chênh l?ch nhi?t ?? gi?a b? m?t và tim s? d?n ??n ?ng su?t bên trong. S? thay ??i pha c?a th? tích riêng c?a ch?t thay ??i pha và d?o thay ??i pha c?ng s? gay ra ?ng su?t chuy?n pha b? sung. N?u ?ng su?t nhi?t và ?ng su?t chuy?n pha ch?ng ch?t, t?c là ?ng su?t t?ng th? v??t quá c??ng ?? n?ng su?t c?a v?t li?u thì s? x?y ra bi?n d?ng d?o; n?u ?ng su?t v??t quá ?? b?n kéo c?a thép nóng s? hình thành v?t n?t d?p t?t. Trong quá trình làm ngu?i c??ng ?? cao, ?ng su?t d? do ?? d?o thay ??i pha gay ra và ?ng su?t d? t?ng do s? thay ??i th? tích riêng c?a quá trình bi?n ??i austenite-martensite. Trong quá trình làm mát c??ng ?? cao, b? m?t ph?i ngay l?p t?c ???c làm mát ??n nhi?t ?? b?, nhi?t ?? tim h?u nh? kh?ng thay ??i. Làm l?nh nhanh gay ra ?ng su?t kéo cao làm co l?p b? m?t và ???c can b?ng b?i ?ng su?t tim. S? gia t?ng c?a gradient nhi?t ?? làm t?ng ?ng su?t kéo do quá trình bi?n ??i mactenxit ban ??u gay ra, trong khi s? gia t?ng nhi?t ?? b?t ??u bi?n ??i mactenxit Ms s? làm cho l?p b? m?t gi?n n? do tính d?o chuy?n pha, ?ng su?t kéo b? m?t s? gi?m và bi?n ??i ?áng k? thành ?ng su?t nén, ?ng su?t nén b? m?t t? l? v?i l??ng mactenxit b? m?t sinh ra. ?ng su?t nén b? m?t này xác ??nh li?u tim có tr?i qua quá trình bi?n ??i martensitic trong ?i?u ki?n nén hay khi làm mát thêm, s? ??o ng??c ?ng su?t kéo b? m?t. N?u s? bi?n ??i mactenxit c?a s? gi?n n? th? tích tim ?? l?n, và mactenxit b? m?t r?t c?ng và giòn, nó s? làm cho l?p b? m?t b? v? do ?ng su?t ??o chi?u. ?? ??t ???c ?i?u này, b? m?t thép ph?i xu?t hi?n ?ng su?t nén và quá trình bi?n ??i martensitic ? tim ph?i x?y ra càng mu?n càng t?t. Th? nghi?m t?i luy?n m?nh và hi?u su?t t?i luy?n thép: Ph??ng pháp t?i luy?n m?nh có ?u ?i?m là hình thành ?ng su?t nén trên b? m?t, gi?m nguy c? n?t và c?i thi?n ?? c?ng và s?c m?nh. S? hình thành b? m?t c?a martensite 100%, thép s? có l?p c?ng l?n nh?t, nó có th? thay th? thép cacbon ??t ti?n h?n, t?i m?nh c?ng có th? thúc ??y các tính ch?t c? h?c ??ng nh?t c?a thép và t?o ra ?? bi?n d?ng nh? nh?t c?a ph?i. Các b? ph?n sau khi làm ngu?i, tu?i th? c?a d?ch v? d??i t?i tr?ng xen k? có th? t?ng lên theo m?t m?c ?? l?n. [1]Hình 2 xác su?t hình thành v?t n?t d?p t?t m?nh và m?i quan h? t?c ?? làm mát3 ph??ng pháp làm mát h?n h?p n??c-kh?ng khíB?ng cách ?i?u ch?nh áp su?t c?a n??c và kh?ng khí và kho?ng cách gi?a vòi phun nguyên t? và b? m?t ph?i, kh? n?ng làm mát c?a h?n h?p n??c-kh?ng khí có th? thay ??i và làm mát có th? ??ng ??u. Th?c ti?n s?n xu?t cho th?y r?ng vi?c s? d?ng quy lu?t v? hình d?ng c?a các b? ph?n làm c?ng b? m?t b?ng thép carbon ho?c thép h?p kim ph?c t?p, có th? ng?n ch?n hi?u qu? vi?c t?o ra các v?t n?t làm ngu?i. , có th? có tác d?ng làm c?ng t?t h?n, ?? làm ngu?i ho?c bình th??ng hóa(chǎn) thép. Hi?n t?i, c?ng ngh? này ?? ???c áp d?ng thành c?ng ?? t?i gang d?o. L?y h?p kim nh?m làm ví d?: Theo các th?ng s? k? thu?t x? ly nhi?t hi?n t?i ??i v?i rèn và rèn h?p kim nh?m, nhi?t ?? n??c t?i th??ng ???c ki?m soát d??i 60 ° C, nhi?t ?? n??c t?i th?p, t?c ?? làm mát cao và d? l??ng l?n c?ng th?ng sau khi d?p t?t x?y ra. Trong quá trình gia c?ng cu?i cùng, ?ng su?t bên trong m?t can b?ng do hình d?ng và kích th??c b? m?t kh?ng ??ng nh?t, d?n ??n gi?i phóng ?ng su?t d?, d?n ??n các ph?n b? bi?n d?ng, u?n cong, hình b?u d?c và các ph?n bi?n d?ng khác c?a b? ph?n gia c?ng tr? thành ch?t th?i cu?i cùng kh?ng th? ph?c h?i v?i t?n th?t nghiêm tr?ng. Ví d?: cánh qu?t, cánh máy nén và các bi?n d?ng rèn h?p kim nh?m khác sau khi gia c?ng r? ràng, d?n ??n dung sai kích th??c các b? ph?n. Nhi?t ?? n??c t?i t?ng t? nhi?t ?? phòng (30-40 ℃) lên nhi?t ?? n??c s?i (90-100 ℃), ?ng su?t d? rèn trung bình gi?m kho?ng 50%. [2]Hình 4 S? ?? làm ngu?i b?ng n??c s?i5 Ph??ng pháp làm ngu?i b?ng d?u nóng Vi?c s? d?ng d?u làm ngu?i nóng ?? ph?i tr??c khi làm ngu?i thêm ? nhi?t ?? b?ng ho?c g?n v?i nhi?t ?? c?a ?i?m Ms ?? gi?m thi?u chênh l?ch nhi?t ??, có th? ng?n ch?n quá trình làm ngu?i m?t cách hi?u qu? s? bi?n d?ng ph?i và n?t. Kích th??c nh? c?a thép c?ng c? h?p kim ch?t ngu?i 160 ~ 200 ℃ trong quá trình làm ngu?i d?u nóng, có th? làm gi?m bi?n d?ng và tránh n?t m?t cách hi?u qu?. austenite ???c gi? l?i ti?p t?c ???c chuy?n thành martensite, m?c ?ích là c?i thi?n ?? c?ng và kh? n?ng ch?ng mài mòn c?a thép, c?i thi?n ?? ?n ??nh c?u trúc và ?? ?n ??nh kích th??c c?a ph?i, ??ng th?i c?i thi?n hi?u qu? tu?i th? c?a d?ng c?. X? ly ??ng l?nh là nit? l?ng nh? m?t ph??ng ti?n làm mát cho các ph??ng pháp x? ly v?t li?u. C?ng ngh? x? ly ??ng l?nh l?n ??u tiên ???c áp d?ng cho các d?ng c? mài mòn, v?t li?u d?ng c? khu?n, sau ?ó ???c m? r?ng sang thép h?p kim, cacbua, v.v., s? d?ng ph??ng pháp này có th? thay ??i c?u trúc bên trong c?a v?t li?u kim lo?i, t? ?ó c?i thi?n tính ch?t c? h?c và tính ch?t gia c?ng, ?ó là hi?n t?i M?t trong nh?ng quy trình c??ng l?c m?i nh?t. X? ly ??ng l?nh (X? ly ??ng l?nh), còn ???c g?i là x? ly nhi?t ?? c?c th?p, th??ng ?? c?p ??n v?t li?u d??i -130 ℃ ?? x? ly nh?m c?i thi?n hi?u su?t t?ng th? c?a v?t li?u. Ngay t? 100 n?m tr??c, ng??i ta ?? b?t ??u x? ly l?nh áp d?ng cho các b? ph?n c?a ??ng h?, giúp c?i thi?n ?? b?n, kh? n?ng ch?ng mài mòn, ?n ??nh kích th??c và tu?i th?. X? ly ??ng l?nh là m?t c?ng ngh? m?i ???c phát tri?n trên c? s? x? ly l?nh th?ng th??ng vào nh?ng n?m 1960. So v?i x? ly l?nh th?ng th??ng, x? ly ??ng l?nh có th? c?i thi?n h?n n?a các tính ch?t c? h?c và ?? ?n ??nh c?a v?t li?u, ??ng th?i có tri?n v?ng ?ng d?ng r?ng h?n. C? ch? x? ly ??ng l?nh: Sau khi x? ly ??ng l?nh, austenite còn l?i trong c?u trúc bên trong c?a v?t li?u kim lo?i (ch? y?u là khu?n v?t li?u) ???c chuy?n thành martensite, và cacbua k?t t?a c?ng ???c k?t t?a trong martensite, do ?ó có th? lo?i b? martensite trong ?ng su?t d?, nh?ng c?ng t?ng c??ng ma tr?n martensite, do ?ó ?? c?ng và kh? n?ng ch?ng mài mòn c?a nó c?ng s? t?ng lên. S? d? ?? c?ng t?ng lên là do s? bi?n ??i m?t ph?n austenit gi? l?i thành mactenxit. S? gia t?ng ?? d?o dai là do s? phan tán và k?t t?a η-Fe3C nh?. ??ng th?i, hàm l??ng carbon c?a martensite gi?m và ?? bi?n d?ng m?ng gi?m, C?i thi?n ?? d?o. Thi?t b? x? ly ??ng l?nh ch? y?u bao g?m b? ch?a nit? l?ng, h? th?ng truy?n nit? l?ng, h?p l?nh sau và h? th?ng ?i?u khi?n. Trong ?ng d?ng, x? ly ??ng l?nh ???c l?p l?i nhi?u l?n. Các quy trình ?i?n hình nh?: t?i d?u 1120 ℃ + -196 ℃ × 1h (2-4) x? ly ??ng l?nh sau + ? 200 ℃ × 2h. Sau khi x? ly t? ch?c, ?? có s? bi?n ??i c?a austenite, nh?ng c?ng ???c k?t t?a t? s? phan tán martensite ?? ???c làm ngu?i có m?i quan h? ch?t ch? cao v?i ma tr?n cacbua siêu m?n, sau khi ? ? nhi?t ?? th?p ti?p theo ? 200 ℃, s? phát tri?n c?a cacbua siêu m?n Phan tán ε cacbua , s? l??ng và ?? phan tán t?ng lên ?áng k?. Vi?c x? ly ??ng l?nh ???c l?p ?i l?p l?i m?t s? l?n. M?t m?t, các cacbua siêu m?n ???c k?t t?a t? martensite ???c bi?n ??i t? austenite ???c gi? l?i t?i th?i ?i?m làm l?nh b?ng ph??ng pháp ??ng l?nh tr??c ?ó. M?t khác, các cacbua m?n ti?p t?c ???c k?t t?a trong mactenxit ?? t?i. Quá trình l?p ?i l?p l?i có th? làm t?ng c??ng ?? nén ma tr?n, c??ng ?? n?ng su?t và ?? b?n va ??p, c?i thi?n ?? d?o dai c?a thép, ??ng th?i làm cho kh? n?ng ch?ng mài mòn do va ??p ???c c?i thi?n ?áng k?. x? ly do ?ng su?t nhi?t gay ra b?i bi?n d?ng quá m?c, t?c ?? làm mát ph?i ???c ki?m soát trong quá trình x? ly b?ng ph??ng pháp ??ng l?nh. Ngoài ra, ?? ??m b?o tính ??ng nh?t c?a tr??ng nhi?t ?? bên trong thi?t b? và gi?m dao ??ng nhi?t ??, thi?t k? c?a h? th?ng x? ly ??ng l?nh c?n tính ??n ?? chính xác ki?m soát nhi?t ?? c?a h? th?ng và tính h?p ly c?a vi?c b? trí tr??ng dòng ch?y. Trong thi?t k? h? th?ng c?ng nên chú y ?áp ?ng tiêu th? ít n?ng l??ng, hi?u qu? cao, v?n hành d? dàng và các yêu c?u khác. ?ay là xu h??ng phát tri?n hi?n nay c?a h? th?ng x? ly ??ng l?nh. Ngoài ra, m?t s? h? th?ng làm l?nh ?ang phát tri?n có nhi?t ?? làm l?nh kéo dài t? nhi?t ?? phòng ??n nhi?t ?? th?p c?ng ???c d? ki?n s? phát tri?n thành h? th?ng x? ly ??ng l?nh kh?ng ch?a ch?t l?ng v?i vi?c gi?m nhi?t ?? t?i thi?u và c?i thi?n hi?u qu? làm l?nh. [3]Tài li?u tham kh?o:[1]樊東黎.強烈淬火——一種新的強化鋼的熱處理方法[J].熱處理, 2005, 20(4): 1-3[2]宋微, 郝冬梅, 王成江.沸水淬火對鋁合金鍛件組織與機械性能的影響[J].鋁加工, 2002, 25(2): 1-3[3]夏雨亮, 金滔, 湯珂.深冷處理工藝及設(shè)備的發(fā)展現(xiàn)狀和展望[J].低溫與特氣, 2007, 25(1): 1-3
Ngu?n: Meeyou cacbua

First, the molecular beam epitaxial profileIn the ultra-high vacuum environment, with a certain thermal energy of one or more molecules (atoms) beam jet to the crystal substrate, the substrate surface reaction processMolecules in the “flight” process almost no collision with the ambient gas, in the form of molecular beam to the substrate, the epitaxial growth, hence the name.Properties: A vacuum deposition methodOrigin: 20th century, the early 70s, the United States Bell laboratoryApplications: epitaxial growth atomic level precise control of ultra-thin multi-layer two-dimensional structure materials and devices (super-character, quantum wells, modulation doping heterojunction, quantum yin: lasers, high electron mobility transistors, etc.); combined with other processes, But also the preparation of one-dimensional and zero-dimensional nano-materials (quantum lines, quantum dots, etc.).Typical features of MBE:(1) The molecules (atoms) emitted from the source furnace reach the substrate surface in the form of a “molecular beam” stream. Through the quartz crystal film thickness monitoring, can strictly control the growth rate.(2) molecular beam epitaxy growth rate is slow, about 0.01-1nm / s. Can achieve single atomic (molecular) layer epitaxy, with excellent film thickness controllability.(3) By adjusting the opening and closing of the baffle between the source and the substrate, the composition and the impurity concentration of the film can be strictly controlled, and selective epitaxial growth can be achieved.(4) non-thermal equilibrium growth, the substrate temperature can be lower than the equilibrium temperature, to achieve low temperature growth, can effectively reduce the interdiffusion and self-doping.(5) with reflective high-energy electron diffraction (RHEED) and other devices, can achieve the original price observation, real-time monitoring.Growth rate is relatively slow, both MBE is an advantage, but also its lack, not suitable for thick film growth and mass production.Second, silicon molecular beam epitaxy1 basic profileSilicon molecular beam epitaxy includes homogeneous epitaxy, heteroepitaxy.The silicon molecular beam epitaxy is the epitaxial growth of silicon (or silicon-related materials) on a suitably heated silicon substrate by physical deposition of atoms, molecules or ions.(1) during the epitaxial period, the substrate is at a lower temperature.(2) Simultaneous doping.(3) the system to maintain high vacuum.(4) pay special attention to the atomic clean surface.Figure 1 Schematic diagram of the working principle of silicon MBE2 Development history of silicon molecular beam epitaxyDeveloped relative to CVD defects.CVD defects: substrate high temperature, 1050oC, to the doping serious (with high temperature). The original molecular beam epitaxy: the silicon substrate heated to the appropriate temperature, vacuum evaporation of silicon to the silicon substrate, the epitaxial growth.Growth Criteria: The incident molecules move sufficiently to the hot surface of the substrate and are arranged in the form of a single crystal.3 The importance of silicon molecular beam epitaxyThe silicon MBE is carried out in a strictly controlled cryogenic system.(1) can well control the impurity concentration to reach the atomic level. The undoped concentration is controlled at <3 × 1013 / cm3.(2) The epitaxy can be carried out under the best conditions without defects.(3) The thickness of the epitaxial layer can be controlled within the thickness of the single atomic layer, superlattice epitaxy, several nm ~ several tens of nm, which can be designed manually, and the preparation of excellent performance of the new functional materials.(4) Homogeneous epitaxy of silicon, heteroepitaxy of silicon.4 epitaxial growth equipmentDevelopment direction: reliability, high performance and versatilityDisadvantages: high prices, complex, high operating costs.Scope: can be used for silicon MBE, compound MBE, III-V MBE, metal semiconductor MBE is developing.Basic common features:(1) basic ultra-high vacuum system, epitaxial chamber, Nuosen heating room;(2) analysis means, LEED, SIMS, Yang EED, etc .;(3) injection chamber.Figure 2 Schematic diagram of silicon molecular beam epitaxial system(1) electron beam bombardment of the surface of the silicon target, making it easy to produce silicon molecular beam. In order to avoid the radiation of the silicon molecular beam to the side to cause adverse effects, large area screen shielding and collimation is necessary.(2) resistance to heating the silicon cathode can not produce strong molecular beam, the other graphite citrus pots have Si-C stained, the best way is to electron beam evaporation to produce silicon source. Because, some parts of the silicon MBE temperature is higher, easy to evaporate, silicon low evaporation pressure requirements of the evaporation source has a higher temperature. At the same time, the beam density and scanning parameters to control. Making the silicon melting pit just in the silicon rod, silicon rods become high-purity citrus.There are several kinds of monitoring molecular beam:(1) Quartz crystal is often used to monitor beam current, beam shielding and cooling appropriate, can be satisfied with the results, but the noise affects the stability. After several μm, the quartz crystal loses its linearity. Frequent exchange, the main system is often inflated, which is not conducive to work.(2) small ion table, measured molecular beam pressure, rather than measuring the molecular beam flux. Due to the deposition on the system components leaving the standard.(3) low-energy electron beam, through the molecular beam, the use of electrons detected by the excitation fluorescence. The atoms are excited and quickly degrade to the ground state to produce uv fluorescence, and the optical density is proportional to the beam density after optical focusing. Do the feedback control of the silicon source. Inadequate: cut off the electron beam, most of the infrared fluorescence and background radiation will make the signal to noise ratio deteriorated to the extent of instability. It only measured atomic class, can not measure molecular substances.(4) Atomic absorption spectra, monitoring the beam density of doped atoms.With the intermittent beam current, Si and Ga were detected by 251.6nm and 294.4nm optical radiation respectively. The absorption intensity of the beam through the atomic beam was converted into atomic beam density and the corresponding ratio was obtained.Molecular beam epitaxy (MBE) substrate base is a difficult point.MBE is a cold wall process, that is, silicon substrate heating up to 1200 ℃, the environment to room temperature. In addition, the silicon wafer to ensure uniform temperature. Hill resistance refractory metal and graphite cathode, the back of the radiation heating, and the entire heating parts are installed in liquid nitrogen cooled containers, in order to reduce the thermal radiation of the vacuum components. The substrate is rotated to ensure uniform heating. Free deflection, can enhance the secondary implantation doping effect.
Ngu?n: Meeyou cacbua

1, Review of Organic Halide Perovskite – related Photoelectric PropertiesFigure 1 Spectral position and PL peakOrganic halide perovskites are widely used in optoelectronics research. Methyl ammonium and formamidine lead iodide as photovoltaics show excellent photoelectric properties and stimulate researchers’ enthusiasm for light-emitting devices and photodetectors. Recently, the University of Toronto Edward H. Sargent (Correspondent) team of organic metal halide perovskite optical and electrical properties of the material were studied. Outlines how material composition and form are associated with these attributes, and how these properties ultimately affect device performance. In addition, the team also analyzed different material properties of the perovskite materials, in particular the bandgap, mobility, diffusion length, carrier lifetime and trap density.The Electrical and Optical Properties of Organometal Halide Perovskites Relevant to Optoelectronic Performance（Adv.Mater.,2017,DOI: 10.1002/adma.201700764）2, Advanced Materials Overview: 2D optoelectronic applications of organic materials Figure 2 Several key steps in the application of two-dimensional organic materialsThe 2D material with atomic thin structure and photoelectron properties has attracted the interest of researchers in applying 2D materials to electronics and optoelectronics. In addition, as a two-dimensional material series of emerging areas, the organic nanostructure assembled into 2D form provides molecular diversity, flexibility, ease of processing, light weight, etc., for optoelectronic applications provides an exciting prospect. Recently, Tianjin University, Professor Hu Wenping, Ren Xiaochen assistant researcher (common newsletter) and others reviewed the application of organic two-dimensional materials in optoelectronic devices. Examples of materials include 2D, organic, crystalline, small molecules, polymers, self- Covalent organic skeleton. The application of 2D organic crystal fabrication and patterning technology is also discussed. Then the application of optoelectronic devices is introduced in detail, and the prospect of 2D material is briefly discussed.2D Organic Materials for Optoelectronic Applications（Adv.Mater.,2017,DOI: 10.1002/adma.201702415）3, Advanced Materials Review: 2D Ruddlesden-Popper Perovskite PhotonicsFigure 3 Schematic diagram of 3D and 2D perovskite structuresThe traditional 3D organic-inorganic halide perovskite has recently undergone unprecedented rapid development. However, their inherent instabilities in moisture, light and calories remain a key challenge before commercialization. In contrast, the emerging two-dimensional Ruddlesden-Popper perovskite has received increasing attention due to its environmental stability. However, 2D perovskite research has just started. Recently, the University of Fudan University, Liang Ziqi (Corresponding author) team published a review first introduced 2D perovskite and 3D control of a detailed comparison. And then discussed the two-dimensional perovskite organic interval cationic engineering. Next, quasi-two-dimensional perovskites between 3D and 2D perovskites were studied and compared. In addition, 2D perovskite unique exciton properties, electron-phonon coupling and polaron are also shown. Finally, a reasonable summary of the structure design, growth control and photophysics research of 2D perovskite in high performance electronic devices is presented.2D Ruddlesden–Popper Perovskites for Optoelectronics（Adv.Mater.,2017,DOI: 10.1002/adma.201703487）4, Science Advances Summary: Lead Halide Perovskite: Crystal-Liquid Binary, Phonon Glass Electronic Crystals and Great Polaron FormationFigure 4 CH3NH3PbX3 perovskite structureLead anodized perovskite has proven to be a high performance material in solar cells and light emitting devices. These materials are characterized by the expected coherent band transport of crystalline semiconductors, as well as the dielectric response and phonon dynamics of the liquid. This “crystal-liquid” duality means that lead halide perovskites belong to phonon glass electron crystals – a class of thermoelectric materials that are considered to be the most efficient. Recently, the University of Columbia Zhu Xiaoyang (communication author) team reviewed the crystal-liquid duality, the resulting dielectric response responsible for the formation and selection of carrier polaron, which causes perovskite with defect tolerance, moderate Of the carrier mobility and the combined performance of the radiation. Large polaron formation and phonon glass characteristics can also explain the significant reduction in carrier cooling rates in these materials.Lead halide perovskites: Crystal-liquid duality, phonon glass electron crystals, and large polaron formation（Sci. Adv.,2017,DOI:10.1126/sciadv.1701469）5, Progress in Polymer Science Review: Lithography of silicon-containing block copolymersFig.5 Melt phase diagram of diblock copolymerRecently, the National Tsinghua University Rong-Ming Ho (Correspondent) and others published a summary of the different methods through the preparation of ordered block copolymer (BCP) film the latest progress, focusing on the use of silicon-containing BCP as lithography applications. With the advantages of Si-containing blocks, these BCPs have smaller feature sizes due to their high resolution, large segregation intensity and high etch contrast. Considering that poly (dimethylsiloxane) (PDMS) has been extensively studied in Si-containing BCPs, the possibility of photolithography using PDCP-containing BCP has been demonstrated through previous and ongoing studies. Subsequent sections detail the main results of the DSA approach. The new trend of lithographic printing application and the application of photolithography nano – pattern using silicon – containing BCPs are also discussed. Finally, the conclusion and prospect of BCP lithography are introduced.Silicon-Containing Block Copolymers for Lithographic Applications（Prog. Polym. Sci.,2017,DOI:10.1016/j.progpolymsci.2017.10.002）6, Angewandte Chemie International Edition Overview: CH3NH3PbI3 perovskite solar cell theoretical studyFigure 6 Electronic density patternPower conversion efficiency (PCEs) of more than 22% of the hybridized perovskite perovskite solar cells (PSCs) has attracted considerable attention. Although perovskite plays an important role in the operation of PSCs, the basic theory associated with perovskite remains unresolved. Recently, Professor Xun Nining (Communication Author) of Xi’an University of Architecture and Technology, according to the first principle, evaluated the existing theory of structure and electronic properties, defects, ion diffusion and transfer current of CH3NH3PbI3 perovskite, and ion transport Influence on PSC Current – Voltage Curve Hysteresis. The moving current associated with the possible ferroelectricity is also discussed. And emphasizes the benefits, challenges and potential of perovskite for PSCs.Theoretical Treatment of CH3NH3PbI3 Perovskite Solar Cells（Angew. Chem. Int. Ed.,2017,DOI: 10.1002/anie.201702660）7, Chemical Society Reviews Overview: Reductive Batteries for Electromechanical Active Materials for Molecular EngineeringFigure 7 Molecular engineering for redox substances for sustainable RFBAs an important large energy storage system, redox batteries (RFBs) have high scalability and independent energy and power control capabilities. However, conventional RFB applications are subject to performance and limitations on high cost and environmental issues associated with the use of metal-based redox substances. Recently, the University of Texas at Austin Guihua Yu (communication author) team proposed the design of these new redox substances system molecular engineering program. The article provides a detailed synthesis strategy for modifying organometallic and organometallic redox substances in terms of solubility, oxidation-reduction potential and molecular size. And then introduced recent advances covering the reaction mechanism of the redox species classified by its molecular structure, the specific functionalization methods and electrochemical properties. Finally, the author analyzes the future development direction and challenge of this emerging research field.Molecular engineering of organic electroactive materials for redox flow batteries （Chem.Soc.Rev.,2017,DOI: 10.1039/C7CS00569E）8, Chemical Society Reviews Overview: Atomic level for energy storage and conversion Non-layered nanomaterialsFigure 8 Atomic-grade layered and non-layered nanomaterialsSince the discovery of graphene, the two-dimensional nanomaterials with large atomic thickness and large lateral dimension are highly studied because of their high specific surface area, heterogeneous electronic structure and attractive physical and chemical properties. Recently, Wulonggong University Dushi University academician (communication author) team comprehensively summed up the atomic thickness of non-layered nano-materials preparation method, studied its heterogeneous electronic structure, the introduction of electronic structure operation strategy, and outlined its energy storage and conversion Applications, with particular emphasis on lithium-ion batteries, sodium ion batteries, oxygen, CO2 reduction, CO oxidation reaction. Finally, based on the current research progress, put forward the future direction – in practical application to enhance the performance and new features to explore.Atomically thin non-layered nanomaterials for energy storage and conversion （Chem.Soc.Rev.,2017,DOI:10.1039/C7CS00418D）9, Chemical Reviews Overview: Electrochemical Applications in the Synthesis of Heterocyclic StructuresFigure 9 Mechanism of electro-induced cationic chain reactionThe heterocycle is one of the largest organic compounds to date, and the preparation and transformation of heterocyclic structures have been of great interest to organic chemistry researchers. Various heterocyclic structures are widely found in biologically active natural products, organic materials, agrochemicals and drugs. When people notice that about 70% of all drugs and agrochemicals have at least one heterocycle, people can not ignore them importance. Recently, Professor Zeng Chengchao of Beijing University of Technology (Correspondent Author) team reviewed the progress of electrochemical construction of heterocyclic compounds published by intramolecular and intermolecular cyclization since 2000.Use of Electrochemistry in the Synthesis of Heterocyclic Structures（Chem. Rev.,2017,DOI:10.1021/acs.chemrev.7b00271）
Ngu?n: Meeyou cacbua

First, the development of a brief historyThe first stage: 1945 to 1951, the invention of nuclear magnetic resonance and lay the theoretical and experimental basis of the period: Bloch (Stanford University, observed in the water proton signal) and Purcell (Harvard University, observed in the paraffin proton signal) obtained Nobel bonus.The second stage: 1951 to 1960 for the development period, its role by chemists and biologists recognized, to solve many important problems. 1953 appeared in the first 30MHz nuclear magnetic resonance spectrometer; 1958 and early in the emergence of 60MHz, 100MHz instrument. In the mid-1950s, 1H-NMR, 19F-NMR and 31P-NMR were developed.The third stage: 60 to 70 years, NMR technology leap period. Pulse Fourier transform technology to improve the sensitivity and resolution, can be routinely measured 13C nuclear; dual frequency and multi frequency resonance technology;The fourth stage: the late 1970s theory and technology development mature.1,200, 300, 500 MHz and 600 MHz superconducting NMR spectrometers;2, the application of a variety of pulse series, in the application made important development;3, 2D-NMR appeared;4, multi-core research, can be applied to all magnetic cores;5, there have been “nuclear magnetic resonance imaging technology” and other new branch disciplines.Second, the main purpose:1. Determination and confirmation of the structure, and sometimes can determine the configuration, conformation2. Compound purity inspection, the sensitivity of thinner, paper chromatography high3. Mixture analysis, such as the main signal does not overlap, without separation can determine the proportion of the mixture.4. Proton exchange, the rotation of a single bond, the transformation of the ring and other chemical changes in the speed of the presumption1. the spin of the nucleusOf the isotopes of all elements, about half of the nuclei have spin motion. These spin nuclei are the object of nuclear magnetic resonance. Spin Quantum: The number of quantum numbers describing the spin motion of the nucleus, which can be an integer, a half integer, or a zero.In the organic compound composition elements, C, H, O, N is the most important element. In its isotopes, 12C, 16O are non-magnetic and therefore do not undergo nuclear magnetic resonance. 1H natural abundance of large, strong magnetic, easy to determine, so the NMR study was mainly for the proton. 13C abundance is small, only 12C 1.1%, and the signal sensitivity is only a proton to get 1/64. So the total sensitivity of only 1/6000 of 1H, more difficult to determine. But in the past 30 years, nuclear magnetic resonance instrument is greatly improved, can be measured in a short time 13C spectrum, and give more information, has become the main means of NMR. 1H, 19F, 31P natural abundance of large, strong magnetic, and nuclear charge distribution of spherical, the most easy to determine.2. Nuclear magnetic resonance phenomena① Precession: Spin with a certain magnetic moment Under the action of external magnetic field H0, this core will form angle for the kinematic motion: is the precession kinematic velocity, which is proportional to H0 (external magnetic field strength).② spin nuclear in the external magnetic field orientation: no external magnetic field, the spin magnetic orientation is chaotic. The magnetic core is in the external magnetic field H0, with (2I + 1) orientation. The spin of the magnetic core in the external magnetic field can be analogous to the precession (pronation, swing) of the gyroscope in the gravitational field.③ conditions of nuclear magnetic resonanceThe magnetic resonance magnetic field must have the magnetic nuclei, the external magnetic field and the RF magnetic field. The frequency of the RF magnetic field is equal to the precession frequency of the spin nucleus, and the resonance occurs from the low energy state to the high energy state.④ nuclear magnetic resonance phenomenon:In the vertical direction of the external magnetic field H0, a rotating magnetic field H1 is applied to the precession nucleus. If the rotational frequency of H1 is equal to the rotational precession frequency of the nucleus, the precession nucleus can absorb energy from H1 and transition from low energy state to high energy state Nuclear magnetic resonance.3. Saturation and relaxationLow energy nuclear is only 0.001% higher than high energy nuclear. Therefore, the low energy state core is always more than the high energy nuclear, because such a little surplus, so can observe the absorption of electromagnetic waves. If the nuclear continuous absorption of electromagnetic waves, the original low energy state is gradually reduced, the intensity of the absorption signal will be weakened, and ultimately completely disappeared, this phenomenon is called saturation. When saturation occurs, the number of cores in the two spin states is exactly the same. In the external magnetic field, the low-energy nuclei are generally more nuclear than the high-energy state, absorb the electromagnetic wave energy and migrate to the high-energy state of the core will be released by a variety of mechanisms of energy, and return to the original low energy state, this process called relaxation.4. Shield effect – chemical shift① ideal state of resonanceFor isolated, bare nuclei, ΔE = (h / 2π) γ · H;Under certain H0, a nucleus has only one ΔEΔE = E outside = hνOnly the only frequency ν of absorptionSuch as H0 = 2.3500T, 1H absorption frequency of 100 MHz, 13C absorption frequency of 25.2 MHz② real core: shielding phenomenonNuclear outside the electron (not isolated, not exposed)In the compounds: the interatomic binding (role) is different, such as chemical bonds, hydrogen bonds, electrostatic interactions, intermolecular forcesImagine: In H0 = 2.3500 T, due to the outer electrons of the shield, in the nuclear position, the real magnetic field is slightly smaller than 2.3500 TResonance frequency slightly higher than 100 MHzHow much is it? 1H is 0 to 10, and 13C is 0 to 250The hydrogen nuclei have electrons outside, and they repel the magnetic field lines of the magnetic field. For the nucleus, the surrounding electrons are shielded (Shielding) effect. The greater the density of the electron cloud around the core, the greater the shielding effect, the corresponding increase in magnetic field strength to make it resonant. The electron cloud density around the nucleus is affected by the connected groups, so the nuclei of different chemical environments, they suffer from different shielding effects, their nuclear magnetic resonance signals also appear in different places.③ If the instrument is measured with a 60MHz or 100MHz instrument, the electromagnetic wave frequency of the organic compound proton is about 1000Hz or 1700Hz. In determining the structure, the need to determine the correct resonant frequency, often requires several Hz accuracy, generally with the appropriate compound as the standard to determine the relative frequency. The difference between the resonant frequency of the standard compound and the resonant frequency of a proton is called the chemical shift.5. H NMR spectroscopy informationThe number of signals: how many different types of protons are present in the moleculeThe position of the signal: the electronic environment of each proton, the chemical shiftThe intensity of the signal: the number or number of each protonSplit situation: how many different protons are presentThe chemical shift of common types of organic compounds① induced effect② conjugate effectThe conjugation effect is weak or enhanced by proton shielding due to the displacement of the π electrons③ anisotropic effectIt is difficult to explain the chemical shift of H with respect to pi-electrons, and it is difficult to explain the electronegativity④ H key effectROH, RNH2 in 0.5-5, ArOH in 4-7, the range of change, the impact of many factors; hydrogen bonding with temperature, solvent, concentration changes significantly, you can understand the structure and changes related to hydrogen bonds.⑤ solvent effectBenzene forms a complex with DMF. The electron cloud of the benzene ring attracts the positive side of the DMF, rejecting the negative side. α methyl is in the shielding region, the resonance moves to the high field; and β methyl is in the masking region, the resonance absorption moves to the low field, and the result is that the two absorption peak positions are interchanged.
Ngu?n: Meeyou cacbua