The effect of sintering conditions on the properties of WC–10wt%Co PIM compacts

Abstract

The powder injection molding (PIM) process has an advantage of near net shaping of homogeneous micro structure and density at the complicate form. This study was investigated for microstructure and mechanical properties of WC–10%Co insert tool alloy fabricated by PIM process. The WC–10%Co feedstock mixed with wax binder was fabricated by two blade mixer. After WC–10%Co feedstocks were injection molded, debinding process was carried by two-steps methods with solvent extraction and thermal debinding. The binder was eliminated with normal hexane for 12 h at 50 °C by solvent extraction, and subsequently thermal debinding was examined for 1 h at the temperature 900 °C. After debinding process, the specimens were sintered at vacuum or N₂/H₂ mixed gas atmosphere at 1380 °C. The microstructure and phase were observed by FE-SEM. In the case of sintered at 1380 °C in vacuum atmosphere, the hardness was 1600 Hv, and the relative density of WC–10%Co was 92.5%. The density of WC–10%Co sintered at 1380 °C in mixed gas atmosphere was 87.5% and the hardness was lower than 1400 Hv. Residual carbon contents of sintered at vacuum and mixed gas atmosphere were 5.4 wt%.