Extended arc thermal plasma assisted sintering of Al-Zr oxide composites

Abstract

An inexpensive and simple sintering technique using an extended arc thermal plasma assisted heating (EATPAH) source has been designed and fabricated for rapid sintering of Al-x-Zr100-x (x = 0, 10, 20,..., 100) oxide composites. High heat and mass transfer kinetics of thermal plasma assisted heating allows quick densification within a few minutes when compared with conventional heating source that takes tens of hours for identical densification. Sintering parameters such as sintering time, plasma power and plasmagen gas flowrate, and initial green density of composites are critically optimized. The green powder compacts sintered at a higher heating rate produced a sample with higher density and fine grain microstructure, whereas abnormal grain growth and lower density result at lower heating rate. This reveals that rapid sintering by EATPAH is effective for promoting the physical densification of the sintered end product. Hardness of the sintered products is studied to understand the density and shrinkage behaviour during plasma sintering. It is observed that highly dense sintered product with greater hardness and homogeneous phase distribution can be prepared within a few minutes by low cost EATPAH technique.