Preparation method of surface-carburizing gradient hard alloy

Abstract

The invention discloses a preparation method of a surface-carburizing gradient hard alloy. The preparation method is characterized in that heat preservation is conducted for 2-4 h at the temperature ranging from 550 DEG C to 750 DEG C, and a hard alloy green body of a removal forming agent with the porosity ranging from 25% to 40% is formed; then, core / shell structure powder, graphene and BaCO3 are mixed according to the weight percentage being 1 to 2 to 1 to prepare a hydrogen-containing carburizing medium, wherein TiH2 is wrapped by SiO2 in the core / shell structure powder, the thickness of the graphene is smaller than 3 nm, the layer number of the graphene is smaller than 3, and the specific surface area of the graphene is larger than 250 m<2> / g; then, the green body is buried in the hydrogen-containing carburizing medium and is compacted under the pressure ranging from 5 MPa to 15 MPa; and finally, liquid-phase sintering is conducted, and the surface-carburizing gradient hard alloy is prepared. The preparation method solves the problems that an existing process is serious in grain growth, long in carburizing time and low in efficiency, and the surface-carburizing gradient hard alloy is prepared in the sintering process.

Description

technical field

[0001] The invention relates to a method for preparing hard alloy, in particular to a method for preparing surface carburized gradient hard alloy, which belongs to the field of hard materials. Background technique

[0002] As a new tool material, cemented carbide is based on refractory metal hard compounds (usually referring to carbides, nitrides, borides and silicides of transition elements in the periodic table of elements, etc.), based on iron group Metals (such as cobalt, nickel, iron) are used as bonding metals, which are high hardness and high wear resistance materials manufactured by powder metallurgy. However, it is difficult for homogeneous materials to meet more and more complex working conditions. With the concept of gradient cemented carbide, people pay attention to improving material properties by carburizing the surface.

[0003] CN102002664A discloses a preparation method of gradient structure cemented carbide. First, the surface oxidation met...

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