Consolidation of ceramic nanopowders

Abstract

This review is dedicated to the problems of nanostructured ceramics consolidation.Laboratory practice in recent years has displayed several potentially important technologies for consolidation of ceramic nanopowders, such as spark plasma sintering, high pressure sintering and rate controlled sintering. The grain growth factor in these processes was found to be less than 10. These advanced technologies have to be adapted to consolidation of nanopowders and require nanopowders specifically designed for consolidation purposes. When adapted to nanopowders, these techniques must be accomplished in rapid rate mode to eliminate residual porosity and retain nanosize grains. Practical verification, however, has exposed problems such as large residual porosity, stable pores in triple junctions, defective grain boundaries and intensive grain growth. All these problems can be avoided when the temperature–pressure–time schedule of sintering is optimised with respect to minimal grain growth.