Cyclic infiltration of porous zirconia preforms with a liquid solution of mullite precursor

Composites of mullite and zirconia were fabricated via the cyclic infiltrat ion of porous zirconia-based preforms with a liquid mullite precursor. The maximal amount of mullite precursor that could be infiltrated was dependent primarily on the initial open porosity of the preforms, When a zirconia pr eform with an initial open porosity of similar to 58% was cyclically infilt rated to saturation, the open porosity was reduced to similar to 43%, with a median pore diameter of 15 nm, After sintering at a temperature of 1500 d egreesC for 2 h, the saturation-infiltrated zirconia preforms could be dens ified to similar to 98% of the theoretical density. In zirconia samples, in filtrated mullite had a tendency to coalesce into large, elongated grains a s the sintering temperature was increased. The presence of infiltrated mull ite did not have a significant effect on the zirconia grain structure. The distribution of mullite in the samples was nonuniform, and the distribution profiles varied as the number of infiltration cycles varied. Although the sintered density and hardness showed small improvements after saturation in filtration, the fracture toughness did not increase.