Shi Xiaoliang

Powder Extrusion Molding of Nanocrystalline WC-10Co Composite Cemented Carbide

The rods that were shaped from nanocrystalline WC-10.21 Co-0.42 VCI Cr3 C2(wt%) composite powders by using powder extrusion molding (PEM) were investigated. The nanocrystalline WC-10.21 Co-0.42 VC/Cr3 C2 (wt%) composite powders were prepared by the spray thermal decomposition-continuous reduction and carburization technology. In order to improve the properties of rods shaped by using powder extrusion molding, the cold isostatic pressing (CIP) technology was used before or after debinding. Specimens were sintered by vacuum sintering and hot isostatic pressing (HIP). The density, Rockwell A hardness, magnetic coercivity, and magnetic saturation induction of sintered specimen were measured. The microstructure of the green bodies and the sintered specimens was studied by scanning electron microscopy (SEM). Results show that the rod formed by using powder extrusion molding after debinding and followed by cold isostatic pressing can be sintered to 99.5% density of composite cemented carbide rods with an average grain size of about 200–300 nm, magnetic coercivity of 30.4 KA/m, Rockwell A hardness of 92.6 and magnetic saturation induction of 85%. Superfine WC-10Co cemented carbide rods with excellent properties were obtained.

Influences of Carbon Content on the Properties and Microstructure of Ultrafine WC-10Co Cemented Carbide

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.