An ambiguity in the available experimental data on the presumably faster spark-plasma sintering (SPS) densification kinetics compared with conventional hot pressing of powders is pointed out. A hypothesis of the major impact of the evolution of the inter-particle contact area on the densification rate is put forward. It is argued that properly controlled interplay between surface diffusion and external pressure-imposed creep provides better efficiency of the SPS process. The formulated ideas can be used for the SPS pressure–temperature cycle optimization.

http://www.sciencedirect.com/science/article/pii/S1359646213001115