Study On Ultra-fine WC-10Co Cemented Carbides

Ultra-fine WC-lOCo cemented carbides is a class of materials with high hardness, high strength, mainly used in the cutting areas. In this article, firstly through comparative analysis domestic and foreign YG10 sample’s composition, organization and properties, meanwhile collecting a large literature data, summarized the growth regularity of WC particles during vacuum sintering process. Then with WC、Co powder as raw material, adding VC,Cr3C2, Cr+C powder as grain growth inhibitor, and design Co-based alloys instead of Co as binder phase of cemented carbide. Prepared ultra-fine cemented carbide by vacuum sintering, studied the inhibitors form, composition and Co-based alloys’s influence in structural and mechanical properties of ultra-fine WC-1OCo cemented carbide. The carbide phase composition, distribution and microstructure were analysed by SEM and EDS. Archmedes method is using to test ultra-fine WC-1OCo cemented carbide. Respectively Vickers hardness tester and universal testing machine measuring ultra-fine WC-1OCo cemented carbide’s Vickers hardness and bengding strength.Research indicates that:Fine tungsten carbide particles uniformly distributed is the key to enhance the performance of ultra-fine grain carbide. Diffusion mechanism is better to describe the WC grain growth process than interfacial reaction mechanism during vacuum sintering process. During liquid phase sintering, the higher of the temperature, the longer of the holding time, the more easily of the WC grain growth. When added grain growth inhibitor Cr3C2, WC grain size decreases at first, when the Cr3C2 content exceeds 0.4wt%, WC particles appear abnormal growth of the phenomenon. When Cr3C2 content at 0.4wt%, WC grain growth inhibition effect is most obvious, WC grain size between 0.3～0.5um. With the addition of inhibitors VC, WC grain size decreases at first, when the VC content exceeds 0.3wt%, WC particles appear abnormal growth of the phenomenon. When VC content at 0.3wt%, WC grain growth inhibition effect is most obvious, WC grain size between 0.3～0.4um. Add the same amount of Cr3C2 and VC, compared Cr3C2 and VC, VC can do better suppress the WC particles growth during the sintering process. Although the form of Cr+C’s accession can improve the performance of WC-10Co cemented carbide, but the effect is worse than Cr3C2 under the same condition. When use the Co-based alloy as a binder phase to preparation cemented carbide, it can reduce the melting point of the alloy, the liquid phase can occur below 1280℃, thereby to obtain a homogeneous fine WC particles, the WC particles is the minimum when uses Co-Cr-Mn-C alloys, the average size is between 0.4-0.5um.