Temperature distribution and neck formation of WC–Co combined particles during spark plasma sintering

Based on the experimental investigations, a model that describes the distributions of the current intensity and the temperature increase among the different raw powder particles, as well as its evolution during the spark plasma sintering (SPS) process, has been developed. As calculated by the model, in a WC–Co combined (Co-film coated WC) particle, a majority fraction of the WC particle is heated by the thermal energy transferred from the Co film. The rapid melting and joint of the Co films lead to the fast formation of the sintering necks of the combined particles. The temperature of the combined particles may reach the eutectic temperature of WC and Co and the melting temperature of Co at relatively lower sintering temperatures, thus the powder particles can be densified rapidly at the temperatures apparently lower than those in the conventional sintering techniques. The physical essence of the neck formation and the unique densification feature of the SPS process is presented by combing theoretical analysis and experimental studies.