High Density Unbonded Phase Tungsten Carbide

Cemented carbide is a kind of alloy material made by powder metallurgy process from hard compounds of refractory metals and bonded metals. Cemented carbide has a series of excellent properties, such as high hardness, wear resistance, good strength and toughness, heat resistance and corrosion resistance, so it is known as "industrial teeth".

Therefore, people began to try to produce high density unbonded phase tungsten carbide. In the existing technology, hot pressing sintering (HP) or spark plasma hot pressing sintering (SPS) are usually used to prepare tungsten carbide without bonding phase, but the above methods are relatively complex and require higher equipment. Researchers have proposed a relatively simple process of tungsten carbide cemented carbide with unbonded phase and its preparation method. The process steps include:

Firstly, tungsten powder with fineness of 0.5 micron, purity of 99.5% and fineness of 0.5 micron, carbon powder with purity of 99.5% and massage ratio of 1:1.01 were mixed, and the total quality was controlled to 30 grams.

Then, under the protection of argon atmosphere, the powders were loaded into the ball mill tank, and then put into the high-energy ball mill. The ball mill frequency was 900 rpm. After 6 hours of ball milling, the mixture with fine properties of 50 nm was obtained.

Then, under the protection of argon atmosphere, the mixture obtained by the above steps was cold pressed under 200 MPa pressure to obtain the mixture green body. The above mixture green body was loaded into graphite mould and sintered in a sintering furnace. The sintering temperature was 1600 ℃, the sintering pressure was 20GPa. After 150 minutes of reaction sintering, unbonded tungsten carbide cemented carbide was obtained.

The properties of the unbonded tungsten carbide cemented carbide were tested by referring to the national standard GB/T3850-1983 Density Measurement Method for Dense Sintered Metal Materials and Cemented Carbide. The results show that the relative density, microhardness and bending strength of the prepared tungsten carbide cemented carbide are 99.0%, 21+1.5 GPa and 1204 respectively. The alloy has good properties and (+19 MPa) does not contain binder Co.

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