Pressure effect on the homogeneity of spark plasma-sintered tungsten carbide powder

Abstract

A combined experimental/numerical methodology was developed to aid full densification of pure ultrafine tungsten carbide powder by means of Spark Plasma Sintering (SPS) operating in Current Control mode. Applied pressure ranged from 5 to 80 MPa while the current intensity was set and held constant at 1400 A. The developed SPS model used a moving-mesh technique to account for the electrothermal contact resistance change during both shrinkage and punch sliding follow-up. The pressure dependence on the electrothermal contact resistance was also taken into account by the model. The experimental and numerical results showed the effects of pressure on grain growth, residual porosity, and hardness observed along the sample radius. Upon increasing sintering pressure, complete densification was obtained by reducing the peak temperature measured at the die surface. By combining experimental and modeling results, a direct correlation between compact microstructure homogeneity and sintering parameters (i.e., temperature and applied pressure) was established. © 2009 The American Ceramic Society.