Trace cobalt-containing tungsten carbide without bonding phase and preparation method thereof

Abstract

The invention belongs to the field of powder metallurgy sintering, in particular refers to a trace cobalt-containing tungsten carbide without bonding phase and preparation method thereof. A hard alloy comprises components, by weight, as follows: 0.20-1.00% of Co, 0.01-0.50% of Cr3C2, 0.01-0.50% of VC and the balance of WC with grain size of 0.2-0.8 mum. The preparation method comprises the steps of: carrying out feeding and high energy ball milling according to the above raw material powder ratio, until WC powder in the ball milling powder has an average grain size refined to less than 200nm; then sintering the cemented carbide powder rapidly after the high energy ball milling by discharge plasma. The tungsten carbide base cemented carbide powder of the invention has reasonably designed components and a simple preparation method; the powder gives out heat uniformly and has fast heating and cooling speed, low sintering temperature and short sintering time to save the energy greatly; and the obtained ultrafine-grained WC cemented carbide has excellent integrated properties.

Description

technical field [0001] The invention belongs to the field of powder metallurgy sintering forming, and specifically refers to a tungsten carbide (WC) cemented carbide containing a trace amount of cobalt (Co) and a preparation method thereof. Background technique [0002] Traditional cemented carbide is based on insoluble metal hard compounds, and cobalt, nickel, iron and other metals are used as binder phases. In addition to the function of promoting the full densification of alloy sintering, the binder phase also endows the alloy with toughness and strength, but also reduces its corrosion resistance, high temperature resistance, wear resistance, thermal conductivity, etc., thus making its application field Subject to certain restrictions. Metal-free binder phase cemented carbide, referred to as no binder phase cemented carbide, belongs to a special class of cemented carbide, which can be divided into two series, one is pure WC series and the solid solution of refractory met...

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Problems solved by technology

However, the melting point of pure WC is as high as 2860 °C, and the sintering temperature for preparing fully dense WC cemented carbide without binder phase is very high, and the abnormal growth of WC grains is prone to occur during the sintering process.

In the prior art, the research on the preparation of WC cemented carbide without binder phase mainly focuses on the preparation of pure WC cemented carbide without adding any binder and the preparation of pure WC cemented carbide with carbon. The following problems exist in the preparation process : 1. The sintering temperature is too high and the sintering time is too long. The sintering temperature for preparing fully densified pure WC cemented carbide is above 1800°C; 2. The prepared alloy has the phenomenon of abnormal growth of WC grains, and it is impossible to prepare super Fine-grained WC cemented carbide without binder phase; 3. Since it does not contain any binder, the strength and fracture toughness of the prepared alloy are very low

So far, there has been no report of using spark plasma sintering to prepare a binder-free WC cemented carbide with a small amount of Co