Optimization of Spark Plasma Sintering tooling design

A combined experimental and numerical investigation is conducted with the aim of mitigating radial thermal gradients during the Spark Plasma Sintering (SPS) of silicon nitride. Thanks to a double pyrometer experimental setup significant temperature disparities between the overheated edge and the center of the sample are identified, cause of non-uniform density and microstructure in the final product. Finite element methods are employed to reconstruct the conditions experienced by the entire SPS tooling setup and to develop a parametric study with the punch geometry as optimization parameter. A novel punch design is proposed, consisting in the drilling of holes according to a specific pattern, and whose beneficial impact during the SPS processing of insulating powders is experimentally assessed. The tooling optimization strategy here suggested can provide guidelines for the annihilation of temperature in homogeneities in any material system.