A kind of preparation method of gradient cemented carbide with graphite-rich phase on the surface

Abstract

The invention discloses a preparation method of a gradient cemented carbide with a graphite-rich surface, which is characterized in that it first heats the cemented carbide at 550-750°C for 2-4 hours to form a cemented carbide with a porosity of 25%-40%. Green body; then amorphous Si-C-O-coated TiH2 core / shell structure powder, multi-walled carbon nanotubes with outer diameter less than 8nm, length less than 30μm and specific surface area greater than 350m2 / g, Na2CO3 three kinds of substances by weight The ratio of 1:2:1 is mixed to prepare a hydrogen-containing carburizing medium; then the green body is embedded in the hydrogen-containing carburizing medium and compacted under a pressure of 5~15MPa; finally, liquid phase sintering is carried out to prepare a surface graphite-rich phase gradient cemented carbide. The invention overcomes the problems of severe grain growth, long carburizing time and low efficiency in the prior art, and prepares gradient hard alloy with graphite-rich phase on the surface during the sintering process.

Description

technical field

[0001] The invention relates to a preparation method of cemented carbide, in particular to a preparation method of gradient cemented carbide whose surface is rich in graphite phase, and belongs to the field of hard materials. Background technique

[0002] Cemented carbide has the characteristics of high strength, high hardness, high elastic modulus, wear resistance, corrosion resistance, low thermal expansion coefficient and high chemical stability. It is known as "industrial teeth" and is widely used as cutting tools and drilling tools , wear-resistant parts, etc. In order to improve its friction and wear performance, carburizing treatment can be carried out on the surface to make the surface rich in graphite phase, so as to obtain a good anti-friction effect.

[0003] CN105331868A discloses a preparation method of gradient structure WC-Co cemented carbide. The invention uses the WC-Co cemented carbide billet with a porosity of 15-40% and uniform distributi...

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