Preparation method of WC-Co hard alloy with in-situ addition of rare earth oxide crystal grain refiner

Abstract

The invention discloses a preparation method of WC-Co hard alloy with in-situ addition of a rare earth oxide crystal grain refiner. The method includes following steps: (1) according to proportion, dissolving a soluble salt compound containing cobalt and rare earth in water and preparing cobalt oxide sol-gel doped with the rare earth oxide through a sol-gel method; (2) adding the sol or the gel to original powder with WC as a main component with fully mixing to obtain a mixture; (3) drying the mixture; (4) reducing the mixture with hydrogen; (5) adding wax to the reduced mixture; (6) performing compression moulding forming; and (7) sintering a product. In the invention, a problem of abnormal growth of crystal grain due to non-uniform addition of the rare earth oxides in the prior art, especially, a problem of the growth of crystal grain of cobalt, can be avoided, thereby achieving molecular-grade dispersed distribution of the rare earth oxides in the crystal grain of cobalt and meanwhile achieving inhibition on growth of the crystal grain of WC. Compared with a convention method, the preparation method is high in product purity, is controllable in chemical components and can enable the rare earth oxides to disperse uniformly. The hard alloy is fine in crystal grain and is increased in hardness by 1 HRA, in bending strength by more than 10% and in impact toughness by 30%.

Description

technical field [0001] The invention belongs to the technical field of preparation of WC-Co ultra-fine-grained hard alloys, and in particular relates to a preparation method of WC-Co ultra-fine-grained hard alloys in which a rare earth oxide grain refiner is added in situ. The method can effectively solve the problem of abnormal grain growth in the preparation process of WC-Co cemented carbide. Background technique [0002] Cemented carbide, because of its high strength, high hardness, high thermal conductivity, high temperature resistance, corrosion resistance and a series of excellent properties, is widely used in various industrial fields, such as metal cutting, rock drilling, forming molds, wear-resistant parts , precision components, etc. [0003] With the rapid development of the manufacturing industry, higher and higher requirements are put forward for cemented carbide tool materials. While high strength is required, high hardness is also required, which is the so-c...

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Problems solved by technology

But these methods all have some deficiencies, such as the spray transformation process is complex and the powder particle size is large, the cost of the plasma method is high, the carburizing method is easy to leave a small amount of undecomposed polymer or free carbon in the final product, and the mechanical alloying is difficult. Due to long-term ball milling, it will lead to serious wear debris and an increase in oxygen content, etc.