Ultrafine grain wolfram carbide/ cobalt hard alloy and preparation method thereof

Abstract

The invention discloses an ultrafine grain wolfram carbide (WC) / cobalt hard alloy containing rare-earth hexaboride and a preparation method thereof and belongs to the field of high-performance powder metallurgy materials. The hard alloy comprises the following components in percentage by weight: 0.1 to 2 percent of the rare-earth hexaboride, 0.1 to 0.6 percent of chromium carbide, 0.1 to 0.4 percent of vanadium carbide, 5 to 15 percent of cobalt powder, and the balance of wolfram carbide powder. The preparation method comprises the following steps of: weighing the wolfram carbide powder, the cobalt powder, the rare-earth hexaboride powder, the chromium carbide powder and the vanadium carbide powder with certain granularity in percentage by weight; uniformly mixing the powder by ball milling; pressing the mixture by a mold pressing process to form a green ware body in a certain shape; degreasing the green ware body and sintering the degreased green ware body in a high-temperature low-pressure sintering furnace; and cooling the obtained product along with the furnace to obtain the ultrafine grain wolfram carbide / cobalt hard alloy. The hard alloy has the advantages of rational proportion of the components, simple production process, effective reduction in the grain size of the WC in the hard alloy and improvement on the hardness and fracture toughness of the hard alloy by adulterating the rare-earth hexaboride to inhibit the growth of the wolfram carbide grains in the sintered hard alloy, achievement of high hardness and fracture toughness and application in industrial production.

Description

technical field [0001] The invention discloses an ultra-fine-grained tungsten carbide / cobalt-based hard alloy and a preparation method thereof, in particular to an ultra-fine-grained tungsten carbide / cobalt-based hard alloy and a preparation method thereof. It belongs to the technical field of high-performance powder metallurgy materials. Background technique [0002] Tungsten carbide / cobalt-based cemented carbide is widely used as cutting tool and mold material due to its high hardness and high wear resistance. The strength and wear resistance of tungsten carbide / cobalt-based cemented carbide can be significantly improved by reducing the WC grain size in the alloy to the ultra-fine grain level (1um~300nm). However, in the traditional liquid phase pressureless sintering process, the ultrafine-grained WC particles are prone to abnormal growth. How to control the growth of WC has become one of the key technologies in the preparation of ultrafine-grained tungsten carbide / coba...

AI Technical Summary

Problems solved by technology

The growth of WC particles can be suppressed by means of external force and auxiliary external field, but these methods have the disadvantages of complex production process and high cost, and cannot realize industrial production

Another way to control the growth of ultrafine WC particles is by adding grain inhibitors, such as VC, NbC, Cr 2 C 3 etc., but there is also the phenomenon of abnormal grain growth, and the WC grain size distribution is not uniform

[0004] At present, there is no public report on improving the abnormal grain growth of tungsten carbide / cobalt cemented carbide by adding rare earth hexaboride (ReB6)