Calcia stabilised tetragonal zirconia powders prepared by urea formaldehyde polymeric route

Tetragonal zirconia powder stabilised by 15 mol-% calcia was prepared aia a urea formaldehyde polymeric route. Two different concentrations equivalent to 1 and 4 mole zirconium oxine in the form of zirconium chloride were add ed to the resin during formation. The content of volatiles affected the gra in size of the zirconia phases developed. A change in the dopant content of the tetragonal zirconia phase was detected by EDAX in the original grains, in white spots that appear en near the periphery of the original grains, a nd in small intragranular particles. The growth of the intra-granular parti cles beyond the critical grain size induced stresses that led to partial tr ansformation to the monoclinic phase in powders fired at 1500 degreesC for 2 h and those annealed at 1300 degreesC for 5 h.