Rate controlled sintering: A unique concept for microstructural control

There has been a renewed interest in the use of rate controlled sintering (RCS) technique for the densification of ceramic / metallic nanopowders. The objective is to retain the sintered grains to submicron sizes together with densification. The mechanism involves extension of pore closure through the application of extremely low shrinkage rates at the final densification regime where there is logarithmic dependence of densification with shrinkage rate. The feedback established between the shrinkage rate and instantaneous temperature facilitates the derivation of a temperature-time path best suited to achieve the twin objectives of densification and fine grained microstructure. The paper surveys the systems investigated exploring the suitability of RCS methodology and thermokinetic analysis and presents the case studies carried out on sintering and controlled microstructural evolution in ceramic systems of alumina and zirconia.