Spark plasma sintering as advanced PM sintering method

A short overview of works on spark plasma sintering (SPS) is given in the present paper. SPS is a newly developed rapid sintering technique with a great potential for achieving fast densification results with minimal grain growth in a short sintering time. It is proven by obtained experimental data that enhanced sinterability of powders subjected to SPS mainly associated with particle surface activation and increased diffusion rates on the contact zones caused by applied pulse current. Application of rapid heating results in bypassing of low temperature regions where surface transport controlled sintering is dominant. This preserves the powder surface area to temperature levels where bulk transport is significant. However, the nature of activation effects, especially in its regards to acceleration of diffusion processes, is not clearly established. A lot of research work reports about the occurrence of plasma during the application of pulse current. However, the appearance of thermal plasma during SPS is a controversial issue and plasma-particle interaction is a complex phenomenon. Presently the industrial application of SPS processing is considered mainly in the areas where it is difficult or extremely difficult to obtain high performance materials and where normally HP or hipping processes are applied. Apparently significantly more work is required in this field for better understanding of the entire process and for making a stable ground for more extended industrial application of SPS.