Sintering of WC-Co powder with nanocrystalline WC by spark plasma sintering

Abstract

A 92WC-8Co powder mixture with 33 nm WC grains was prepared by strengthening ball milling and was then sintered by spark plasma sintering (SPS) at 1000–1200°C for 5–18 min under 10–25 kN, respectively. Movement of the position of low punch shown shrinkage of the sintered body began above 800°C. The shrinkage slowly rose as the temperature rose from 800 to 1000°C and then quickly rose at above 1000°C and then gradually rose at above 1150°C. The densities of the samples increased with an increase in sintering temperature, rapidly below 1100°C, and then gradually above 1100°C. WC grains grow gradually with increasing sintering temperature. The powder was sintered to near full density at 1100°C for 5 min under 10 kN. The best result of the sample with 275 run WC grains and no pores was obtained at 1150°C under 10 kN for 5 min. The research found the graphite die had a function of carburization, which could compensate the sintered body for the lack of carbon, and had the normal microstructure.