Preparation method of coarse grain WC-Co hard alloy

Abstract

The invention discloses a preparation method of a coarse grain WC-Co hard alloy. The preparation method comprises the following steps that (1) WC powder is pretreated; (2) an activating solution is prepared, and the WC powder is activated; (3) the activated WC powder is filtered and dried, and heat treatment reduction is carried out to obtain the activated WC powder with metal Co particles attached to the surface; (4) a plating solution is prepared; (5) the activated WC powder with the metal Co particles attached to the surface, C powder and W powder are placed in the plating solution to be subjected to chemical plating, filtering, cleaning and vacuum drying, and WC / C / W / Co coarse grain composite powder is obtained; and (6) a forming agent is added to the WC / C / W / Co coarse grain composite powder, and the WC / C / W / Co coarse grain composite powder is pressed into a blank and then is sintered into the WC-Co hard alloy. According to the method, the coarse-grain WC-Co hard alloy with the grainsize larger than 2 microns is prepared through in-situ reaction sintering, and the grain size, the hardness, the transverse breaking strength and the impact toughness of the coarse-grain WC-Co hard alloy are excellent.

Description

technical field [0001] The present invention relates to a method for preparing cemented carbide; more specifically, it relates to a method for preparing coarse-grained WC-Co cemented carbide. Background technique [0002] Cemented carbide is a composite material with high hardness, high wear resistance, excellent red hardness, thermal stability and corrosion resistance, high strength and excellent toughness. Among them, coarse-grained WC-Co cemented carbide has excellent hardness, wear resistance and high toughness, and is widely used in fields such as geological and mining tools and tunneling tools. In the preparation of coarse-grained WC-Co cemented carbide, WC powder with an average particle size greater than 20 mm is usually prepared by wet grinding method with moderate ball milling intensity to obtain WC / Co composite powder with consistent particle size and uniform dispersion. The particle size is difficult to control, resulting in the distribution of WC particles in t...

AI Technical Summary

Problems solved by technology

In the preparation of coarse-grained WC-Co cemented carbide, WC powder with an average particle size greater than 20 mm is usually prepared by wet grinding method with moderate ball milling intensity to obtain WC / Co composite powder with consistent particle size and uniform dispersion. The particle size is difficult to control, resulting in the distribution of WC particles in the fired alloy being lower than or exceeding the range of the 2-5 mm coarse grain standard, and finally only WC-Co cemented carbide with a broad peak grain distribution is obtained. When the grain size is the same , the strength and toughness of coarse-grained WC-Co cemented carbide with broad peak distribution are lower than those of narrow peak distribution alloys

In addition, ball milling to obtain high-uniformity composite powder will bring high residual stress to WC particles, which is not conducive to the improvement of alloy properties.

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