Preparation method for super coarse crystal WC-Co hard alloy

Abstract

The invention discloses a preparation method for a super coarse crystal WC-Co hard alloy. According to the preparation method, a proper amount of fine tungsten carbide powder is added into a raw material, and the super coarse crystal WC-Co hard alloy is prepared by proper ball milling and sintering processes, so that the super coarse crystal hard alloy with the grain size of 6.0 to 14.0 microns can be prepared successfully. The preparation method has the characteristics that the process is simple, the process is easy to control, the production cost is low, and the WC grain size distribution in the alloy product is uniform.

Description

technical field [0001] The invention relates to the technical field of hard alloy material manufacture, in particular to a preparation method of ultra-coarse-grained WC-Co hard alloy. Background technique [0002] According to ISO4499-2 "Hardmetals-Metallographic determination of microstructure-Part 2: Measurement of WC grain size", cemented carbide with WC grain size ≥ 6.0 μm is called ultra-coarse grained cemented carbide. Ultra-coarse-grained cemented carbide has excellent thermal conductivity, thermal shock resistance, thermal fatigue resistance and high compression deformation work. It is an ideal material for mining, engineering and molds, and it is also one of the development directions of cemented carbide. [0003] The traditional process of preparing cemented carbide is: use tungsten carbide powder and cobalt powder as the main raw materials, form a mixture through batching, ball milling, drying and granulation, and then prepare a product green body with a certain f...

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Problems solved by technology

However, the ultra-coarse tungsten carbide powder will be broken during the ball milling process, and the particle size will be greatly reduced. During the sintering process, the WC grains cannot grow into ultra-coarse grain WC grains. The grain size is also only 3.0-6.0 μm (excerpted from Zhang Li et al. Impact. China Tungsten Industry. 2008, 23-26) and Gille G (Gille G, Szesny B, Dreyer K. Submicron and ultrafine grained hardmetals for microdrills and metal cutting inserts. Int J Refract Met Hard Mater, 2002, 20(1) :3-22) report); if the sintering temperature is excessively increased or the holding time is prolonged, although the WC grains can be coarsened, it will lead to a widening of the WC grain distribution and a decrease in the performance of the cemented carbide; and the reduction of the ball milling strength, although It is possible to keep the tungsten carbide powder in the mixture with a large particle size, but the mixture obtained in this way lacks enough active fine powder, and the retained tungsten carbide powder with a large particle size does not have enough activity, so it cannot be used in Dense cemented carbide prepared in subsequent sintering

Therefore, it is difficult to prepare ultra-coarse-grained cemented carbide with ultra-coarse tungsten carbide powder

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