Complex-shaped TiC/Ti(C,N)-based cermet prepared via rheological press molding using highly-filled granular feedstock

Production of complex-shaped cermet faces challenges owing to its high hardness and brittleness. Plastic shaping is a good solution because the complex-shaped body can be directly formed without machining. In this work, a facile method named rheological press molding (RPM) was raised up, which showed the capability of fabricating TiC/Ti(C,N)-based gear parts with relatively uniform microstructure and high dimensional accuracy. The characteristics of wettability, rheological property and morphology of the polyformaldehyde-based feedstock was measured, and the molding effect including green part molding, debinding and sintering was investigated. The feedstock containing 60 vol% composite powders showed a shear-thinning behavior, with a viscosity lower than 200 Pa·S at 100 S−1. Confirmed by the SEM and XRD results, TiC/Ti(C,N)-based cermets with typical core-rim structure and two phases of Ni-Co metal and Ti(C,N)-based solid solutions were achieved after vacuum sintering at 1500 °C. Good qualified gear parts with polished mirror surface and relative density of 95% were obtained, which showed a linear shrinkage of 12% and the Vicker's hardness of 1482 N/mm2 (Hv10). This method offered an easy and low-cost way to form complex-shaped cermet based on high-filled feedstock.