PREPARATION OF NANOCRYSTALLINE YTTRIA-STABILIZED ZIRCONIA

Nanocrystalline powder with an average crystallite size of 8-12 nm, wh ich was produced by a combustion synthesis process, was used to prepar e dense, nanocrystalline articles. Green compacts of high green densit y were prepared by dry pressing and densified by a fast-firing process . During fast-firing, the dwell temperature significantly affected the final grain size and final density. On the other hand, the ranges of heating rates and dwell times that were used had a much less significa nt effect on the final density and final grain size. It was determined , however, that a high final density (>99% rho(th)) and a very fine fi nal average grain size (<200 nm) can be simultaneously achieved under three: different firing conditions. The high densification rates are, in part, a result of the minimal coarsening that the particles undergo when the sample is taken rapidly through the temperature regime in wh ich surface diffusion predominates to the temperature regime in which the densification mechanisms of grain boundary and lattice diffusion p redominate.