Spark Plasma Extrusion and the Thermal Barrier Concept

Spark plasma sintering (SPS) is currently a major powder consolidation process with many advantages; however, it is still largely limited to the processing of simple shapes such as discs due to its geometric restrictions. Alternatively, spark plasma extrusion (SPE) is a recently developed process that has superiority over SPS in terms of faster consolidation, generating products of extended geometries and potential grain refinement capabilities under applied current. So far, work on SPE has resulted in large temperature gradients within the extruding material with microstructural and properties in-homogeneities. The present paper reports on a novel approach (thermal barrier concept) that allows the SPE of materials with enhanced uniformity in terms of microstructures and properties. Both aluminum and aluminum-carbon nanotube composites have been successfully processed using this new approach.