Hard substance reinforced stabilized zr02 - ceramic with mechanical stability under hydrothermal stress, a method for their preparation and use

摘要

A novel, hard material-reinforced, stabilised ZrO2 ceramic, with mechanical stability under hydrothermal conditions, has the composition (by vol.) 5-50% hard material component with 0.2-1 mu m grain size, 2-45% Al2O3 with 0.1-1 mu m grain size and balance (-30%) stabilised ZrO2 phase with a solid solution of 2-3.5 mol% Y2O3 and 1-7 mol% CeO2 (based on the ZrO2 content in the starting powder composition) and with 0.2-0.7 mu m grain size. Production of the above ceramic involves: (a) providing a ZrO2 powder which contains Y2O3 in solid solution and which is doped with Ce with high spatial distribution homogeneity wrt. the ZrO2 particles, this homogeneity being fixed for the subsequent process steps without significantly modifying the electrokinetic properties at the ZrO2 particle surfaces; (b) subjecting this ZrO2 powder, of less than 0.5 mu mean particle size, to wet mixing and grinding together with a hard material component of less than 5 mu m mean particle size and Al2O3 of less than 0.7 mu m mean particle size, with addition of the requisite organic pressing aid and sintering additive; and (c) moulding and sintering the resulting mixture. Preferably, the hard material component is TiC of any stoichiometry. The stabilised ZrO2 preferably has a primary particle size of 10-60 nm and the Al2O3 preferably contains = 2% coarse particles of greater than 2 mu M size. The sintering additive preferably comprises 2-10 wt.% TiH2.