A method of directly adding refractory metal to prepare gradient cemented carbide

A refractory metal and cemented carbide technology, applied in the field of cemented carbide material manufacturing, can solve the problems of reducing the hardness and strength of alloys, lack of special research, grain growth, etc., and achieve slow decline in surface hardness, long service life, Excellent high temperature oxidation resistance

Active Publication Date: 2017-01-04
株洲金韦硬质合金有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there is an important parameter for gradient cemented carbide, the gradient layer thickness, which has not been specifically studied so far.
The study found that the content and distribution of the decarburized phase have a great influence on the formation of the gradient. It is generally believed that the volume fraction of the decarburized phase is between 5% and 35%, and the performance of the alloy is better; but if you need to obtain a thicker gradient layer, must go through a long-term high-temperature sintering or carburizing process, and this will inevitably cause the grain growth of the surface WC, and the grain growth of WC will reduce the hardness and strength of the alloy

Method used

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  • A method of directly adding refractory metal to prepare gradient cemented carbide
  • A method of directly adding refractory metal to prepare gradient cemented carbide
  • A method of directly adding refractory metal to prepare gradient cemented carbide

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] step one

[0041] The carbon-poor cemented carbide powder containing the refractory metal is press-formed, and then pressurized and sintered to obtain a carbon-poor pre-sintered matrix; the carbon-poor cemented carbide powder containing the refractory metal includes by mass percentage:

[0042] WC powder 87.5%; Co powder 6%; W powder 6%; refractory metal powder Nb 0.5%; the total content of carbon in the carbon-poor cemented carbide powder containing refractory metal is 5.32wt.%.

[0043] The particle size of the WC powder is 2 μm; the particle size of the Co powder is 2.0 μm; the particle size of the W powder is 1.5 μm; the particle size of the refractory metal powder is 1.5 μm;

[0044] Its specific operation has been called:

[0045] According to the mass ratio, binder: carbon-poor cemented carbide powder containing refractory metal = 1:50, put the binder paraffin and the prepared WC powder, Co powder, W powder, and Nb powder into the ball mill In the process, afte...

Embodiment 2

[0062] Other conditions are exactly the same as in Example 1, except that the refractory metal is replaced by V, the forming pressure is 200MPa, and the carburizing temperature is 1440°C; the specific testing items and testing results are shown in Table 3;

[0063] table 3

[0064]

[0065]

[0066] It can be seen from Table 3 and Table 2 that

[0067] The gradient alloy prepared in Example 2 of the present invention, after carburizing for 40 to 240 minutes, has a hardness of more than 90HRA, which is slightly improved compared with the alloy without refractory elements; the transverse fracture strength is increased by about 10 on average; the high temperature hardness is higher than that of ordinary Carbide improves by about 10%. After 240min of carburizing, the grain growth of the alloy is not obvious. And in the whole alloy, the Co content is low in the outer layer, high in the middle layer, and normal in the inner layer.

Embodiment 3

[0069] Other conditions are exactly the same as in Example 1, except that the refractory metal is replaced by Cr, the forming pressure is 300MPa, and the carburizing temperature is 1460°C; the specific testing items and testing results are shown in Table 4;

[0070] Table 4

[0071]

[0072]

[0073] It can be seen from Table 4 and Table 2 that

[0074] The gradient alloy prepared in Example 2 of the present invention, after carburizing for 40 to 240 minutes, has a hardness of above 91HRA, which is slightly improved compared with ordinary cemented carbide, and the transverse fracture strength is obviously improved; compared with that without adding refractory metal elements Alloy improved about 20%, 30% higher than ordinary cemented carbide. The high-temperature hardness is about 10% higher than that of ordinary cemented carbide. And in the whole alloy, the Co content is low in the outer layer, high in the middle layer, and normal in the inner layer.

[0075] It can b...

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Abstract

The invention relates to a method for preparing a gradient hard alloy by directly adding refractory metals, belonging to the field of hard alloy material preparation. The method comprises the following steps: molding carbon-poor hard alloy powder containing refractory elements, performing vacuum sintering so as to obtain a carbon-poor pre-sintered substrate, and performing carburizing treatment for 40-240 minutes at 1400-1460 DEG C in the hydrogen atmosphere, thereby obtaining the gradient hard alloy. As the refractory elements are directly added, a function of inhibiting WC crystal grains from growing up is achieved in the sintering process; in the carburization process, the refractory elements are reacted with activated carbon, and meanwhile the generated refractory metal carbide has a relatively large inhibition function on carburization reaction, so that the gradient layer formation speed is reduced. By appropriately prolonging the carburization time, the problem caused by reduction of the gradient layer formation speed is reduced is solved, the carburization reaction can be performed relatively sufficiently, the content of Co on a surface layer is relatively low, and the purpose of improving the high alloy property is achieved.

Description

technical field [0001] The invention relates to a method for directly adding refractory metals to prepare gradient hard alloys, belonging to the field of hard alloy material manufacturing. Background technique [0002] Cemented carbide is a composite tool material prepared by powder metallurgy with refractory metal compounds (WC, TaC, TiC, NbC, etc.) as the matrix and transition metals (Co, Ni, Fe) as the binder phase. Due to its high strength, high hardness, high elastic modulus, wear resistance, corrosion resistance and other advantages, it plays an important role in metal cutting, wood processing, mining drilling and other aspects. However, there is a sharp contradiction between the hardness and toughness of conventional cemented carbide, and it is difficult to improve the hardness and toughness of the alloy at the same time. In order to overcome this problem, in the 1980s, the Swedish Sandvik company developed a gradient cemented carbide. The Co content of the outer lay...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C1/04C22C29/08C23C8/64
Inventor 刘咏李晓峰吕信群周建华付坤韦伟杜萌
Owner 株洲金韦硬质合金有限公司
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