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Method for preparing microcrystal hard WC-10% Co alloy

A cemented carbide and microcrystalline technology, applied in the field of powder metallurgy, can solve problems such as large particle size, widening of powder particle size distribution, and grain growth, and achieve the effects of fine grain, segregation prevention, and uniform composition

Active Publication Date: 2008-02-06
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] (1) The particle size of the WC-Co composite powder obtained by mechanical ball milling is relatively large. If high-energy ball milling is used, the particle size distribution of the powder is easy to widen, and the powder is easy to contaminate
[0005] (2) Vacuum sintering and hot isostatic pressing sintering can make the sintered cemented carbide produce a cobalt pool, and the sintering time is long and the grains are easy to grow, which affects the performance of the cemented carbide

Method used

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  • Method for preparing microcrystal hard WC-10% Co alloy
  • Method for preparing microcrystal hard WC-10% Co alloy

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0030] Example 1: 75.13 grams of ammonium metatungstate white crystal powder is dissolved in 1000 milliliters of water, another 28.70 grams of high cobalt red crystal powder of nitric acid is dissolved in 100 milliliters of water, after the two solutions are clarified, the two are mixed (wherein Co accounts for The weight percentage of W-Co mixed powder is 10.58%), to be clarified. Using a nitrogen spray gun with a gun pressure of 2 atm, disperse the clear mixed solution in liquid nitrogen. Then place the frozen material frozen in liquid nitrogen in the FTD Dura-stop MP type freeze dryer of FTS company for vacuum drying. 20°C; the working pressure is 150mtorr and the temperature is -15°C within 2700-3900 minutes; the working pressure is 50mtorr and the temperature is -5°C within 3900-4700 minutes; The working pressure is 0 millitorr and the temperature is 15°C; the freeze-dried mixed powder is subjected to secondary reduction, the obtained high cobalt nitrate is decomposed an...

example 2

[0032] Example 2: 56.34 grams of ammonium metatungstate white crystal powder was dissolved in 800 milliliters of water, and 21.52 grams of high-cobalt red crystal powder of nitrate was dissolved in 100 milliliters of water. After the two solutions were clarified, the two were mixed (wherein Co accounted for The weight percentage of W-Co mixed powder is 10.58%), to be clarified. Using a nitrogen spray gun with a gun pressure of 3 atm, disperse the clear mixed solution in liquid nitrogen. Then put the frozen material frozen in liquid nitrogen into the FTD Dura-stop MP type freeze dryer of FTS company for vacuum drying. 15°C; the working pressure is 200mTorr and the temperature is -10°C within 2700-3900 minutes; the working pressure is 100 mTorr and the temperature is -1°C within 3900-4700 minutes; The working pressure is 20 mTorr and the temperature is 28°C; the freeze-dried mixed powder is subjected to secondary reduction, the obtained cobalt nitrate is decomposed and hydrogen...

example 3

[0034] Example 3: 112.69 grams of ammonium metatungstate white crystal powder was dissolved in 1300 milliliters of water, and 43.05 grams of high cobalt red crystal powder of nitric acid was dissolved in 150 milliliters of water. After the two solutions were clarified, the two were mixed (wherein Co accounted for The weight percentage of W-Co mixed powder is 10.58%), to be clarified. Using a nitrogen spray gun with a gun pressure of 2.5 atmospheres, disperse the clear mixed solution in liquid nitrogen. Then put the frozen material frozen in liquid nitrogen into the FTD Dura-stop MP type freeze dryer of FTS company for vacuum drying. 18°C; the working pressure is 180 mTorr and the temperature is -13°C within 2700 to 3900 minutes; the working pressure is 80 mTorr and the temperature is -3°C within 3900 to 4700 minutes; The working pressure is 15 millitorr and the temperature is 20°C; the freeze-dried mixed powder is subjected to secondary reduction, and the obtained high-cobalt...

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Abstract

The present invention relates to a process of a microcrystalline WC-Co (10 percent) hard alloy, belonging to the technology field of powder metallurgy. The problems existing in the prior preparing of hard alloy are that the WC crystal grains are thick and exceptionally big, and the cementing phases are not evenly distributed. The present invention is characterized in that the ammonium metatungstate powders and the cobltic-nitrate powders are respectively dissolved in the water and scattered in the liquid nitrogen to be pre-frozen using a nitrogen spray gun after being mixed and defecated, and then are placed in a freezedryer to be dried vacuumly and finally the powders are obtained. The nanometer powder i.e. the nano tungsten-cobalt composite powder is obtained by reducing the freeze-dried mixed powder in the atmosphere of hydrogen. Soot carbon and inhibitor are added into the reduced powder, well mixed and then an electro discharge plasma sinter is conducted, and a hard alloy is thus obtained. The invention can make the carbonized tungsten and the cobalt mix in the magnitude order of molecular, so the obtained hard alloy is even in granularity distribution and chemical constituent, high in tightness and higher in hardness. The hard alloy is mainly suitable for the cutting and processing of cast iron and heat-resisting alloy steel.

Description

technical field [0001] The invention discloses a preparation method of microcrystalline hard alloy, which belongs to the technical field of powder metallurgy. Background technique [0002] Cemented carbide is mainly based on refractory metal carbides (WC, TiC, etc.), iron group metals (Co, Fe, Ni, etc.) It is also a hard superhard material second only to diamond, which plays a decisive role in the development of industry and social progress. Cemented carbide has high hardness, wear resistance, compressive strength and elastic modulus, and has a certain impact resistance and small thermal expansion coefficient, and has good corrosion resistance and thermal conductivity. It has good red hardness, so it has attracted much attention since its inception. It has been widely used in cutting, rock drilling, forming molds, wear-resistant parts, etc., and has a broad application prospect. [0003] Microcrystalline cemented carbide has many advantages, however. Cemented carbide is a...

Claims

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Application Information

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IPC IPC(8): C22C1/05C22C29/08B22F3/16
Inventor 聂祚仁席晓丽皮雄左铁镛
Owner BEIJING UNIV OF TECH
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