Preparation method of unbonded-phase ultrafine WC hard alloy

Abstract

The invention discloses a preparation method of an unbonded-phase ultrafine WC hard alloy. The unbonded-phase ultrafine WC hard alloy comprises less than 0.5 percent by weight of Co, 0.3-1.0 percent by weight of grain growth inhibitor and the balance of WC. The method comprises the following steps: mixing ultrafine WC compound powder containing a small amount of grain growth inhibitor prepared by using a spray thermal reduction method and ultrafine WC-Co compound powder serving as raw materials in a certain ratio; adding less than 0.4 percent by weight of carbon black powder, and performing high-energy ball milling for 36-72 hours; and sintering by using a hot pressing or hot isostatic pressing or air pressure reactive sintering method at the temperature of 1,550-1,750 DEG C for 1-3 hours. The prepared unbonded-phase ultrafine WC hard alloy has superior comprehensive performance, the Vickers hardness is up to 3,000-3,500HV0.05, the fracture toughness is up to 7.1-8.0MPa.m<1 / 2>, the transverse fracture strength is up to 900-1,200MPa, and the grain size is 0.2-0.5 micron. The novel hard alloy can be widely applied to fields requiring high wear resistance and high corrosion resistance.

Description

Technical field: [0001] The invention relates to a preparation method of superfine WC hard alloy without binder phase. Background technique: [0002] Conventional cemented carbide is a very important tool material composed of WC hard phase and γ-Co binder phase. It has high strength, high hardness, high elastic modulus, wear resistance, corrosion resistance, and low thermal expansion coefficient. And high chemical stability and other characteristics, widely used as cutting tools, drilling tools, wear-resistant parts and so on. The strength and toughness of WC-Co cemented carbide increase with the increase of Co content, but at the same time, the increase of Co content also reduces the wear resistance and corrosion resistance of cemented carbide. Therefore, in some special occasions, such as the working environment that requires high hardness, high wear resistance and high corrosion resistance, the traditional WC-Co cemented carbide can no longer meet the requirements, so ...

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Problems solved by technology

However, during the mixing process of ball milling, it is difficult to distribute the trace amount of Co and the grain growth inhibitor evenly in the raw material powder system, which can easily cause the component segregation of the trace amount of Co and the grain growth inhibitor, resulting in abnormal WC grains during the sintering process. Non-uniform growth makes the material exhibit unstable mechanical properties, which ultimately seriously affects the performance of ultrafine cemented carbide without a binder phase. Therefore, ultrafine cemented carbide without a binder phase has not been able to be widely used in practice.

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