WC-10Co nanocrystalline composite powders prepared by spray pyrogenation-continuous reduction and carburization technology were consolidated by vacuum sintering plus hot isostatic pressing (HIP). Influences of carbon content on properties and microstructure of ultrafine WC-10Co cemented carbide were investigated. The results show that the relative density of the ultrafine WC-10Co cemented carbides can reach 99.72%,and the transverse rupture strength (TRS) was higher than 3 890 MPa,Rockwell A hardness (HRA) was higher than 92.5,the average grain size was less than 460 nm,when carbon content in nanocrystalline composite powder was 5.54wt% and the ball-milled time was 48 hours,ultrafine WC-10Co cemented carbide with excellent properties and homogeneous microstructure was obtained.
Nanocrystalline WC-Co composite powder and coated tungsten diamond by using vacuum vapor deposition were consolidated by the spark plasma sintering (SPS) process to prepare diamond-enhanced WC-Co cemented carbide composite materials. The interface microstructures between coated tungsten diamond and WC-Co cemented carbide matrix were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). The results showed that there is a transitional layer between the diamond and the matrix, in which the carbon content is 62.97wt.%, and the content of cobalt in the transitional zone is 6.19wt.%; the content of cobalt in the WC-Co cemented carbide matrix is 6.07wt.%, in which the carbon content is 15.95wt.%, and the content of cobalt on the surface of diamond is 7.30wt.%, in which the carbon content is 80.38wt.%. The transitional zone prevents the carbon atom of the diamond from spreading to the matrix, in which the carbon content does coincide with the theoretical value of the raw nanocomposite powders, and the carbon content forms a graded distribution among the matrix, transitional zone, and the surface of diamond; after the 1280°C SPS consolidated process the diamond still maintains a very good crystal shape, the coated tungsten on the surface of the diamond improves thermal stability of the diamond and increases the bonding strength of the interface between the diamond and the matrix.
SHI Xiaoliang SHAO Gangqin DUAN Xinglong YUAN Runzhang
WC-10Co nanocomposite powder produced by spray pyrolysis-continuous reduction and carbonization technology was used, and the vacuum sintering plus sinterhip process was adopted to prepare ultrafine WC-Co cemented carbide. The microstructure, grain size, porosity, density, Rockwell A hardness (HRA), transverse rupture strength (TRS), saturated magnetization and coercivity force were studied. The experimental results show that average grain size of the sample prepared by vacuum sintering plus sinterhip technology was about 420 nm, transverse rupture strength was more than 3460 MPa, and Rockwell A hardness of sintered specimen was more than 92.5. Ultrafine WC-10Co cemented carbide with high strength and high hardness is obtained.
