CRYSTALLIZATION OF MULLITE-ZIRCONIA AMORPHOUS MATERIALS PREPARED BY RAPID-QUENCHING.

Amorphous materials have been prepared by rapid quenching, approximately 10**5** degree C/s, of the melt of the mixed oxides, 20wt% ZrO//2-80wt% (3. 4 Al//2O//3 multiplied by (times) 2 SiO//2) using an arc-imaging furnace and a twin-roller. This paper deals with the crystallization and the products of these amorphous materials obtained by reheating under various conditions. The crystallization of this amorphous material took place at approximately 990 degree C precipitating t-ZrO//2 and mullite phases after showing glass-transition temperature at 919 degree C on heating by 10 degree C/min. The mullite had markedly larger lattice parameters than that of stoichiometric mullite (3Al//2O//3 multiplied by (times) 2SiO//2) indicating higher ( greater than 83wt%) Al//2O//3 contents in the early stage of crystallization, then showed smaller lattice parameters on prolonged reheating.