PRODUCTION AND CHARACTERISATION OF ULTRA FINE PARTIALLY STABLISED ZIRCONIA POWDERS BY SOL- GEL PROCESS

Abstract

The rapid increase in the use of ceramic materials for their mechanical capabilities has been brought about by the developement of the high temperature, high strength materials Sia N4 and SIC. With a fracture toughness of only 5 - 6 MN/m312, however, they can not begin to approach the high level of toughness found in metals. The solution to the problem of brittle ceramics is, of course, the achievement of very tough properties in partially stabilized zirconia (PSZ). A technique that utilizes the martensitic transformation of the crystalline form of Zr02 from tetragonal (the high temperature form) to monoclinic (the low temperature form) has Fed to the achievement of high values of toughness, of at least 10 MM/m312, not hitherto observed in ceramic materials. In the present project work, attempts have been made to produce and characterise the ultra fine partially stabilised zirconia (PSZ) powders by sol-gel process. Both the pure zirconia powder and yittria doped partially stabilised zirconia powder have been produced by sol-gel process. The powders so produced have been characterised. For characterisation of powders the particle sizes, apparent densities and green densities have been determined and a comparison of pure zirconia powder and PSZ powder has also been made. It has been found that the PSZ powder exhibits the better characteristics than the pure zirconia powder, produced under the similar conditions. The project work is, thus a step towards the production of ultra fine partially stabilized zirconia powder for it's use as a ceramic material in near future. C