STRUCTURE EVOLUTION IN ZRO2-Y2O3-AL2O3 GEL

Coprecipitation of nitrates followed by heat treatment was used to pre pare a ZrO2-Y2O3-Al2O3 gel. After air drying, the product consisted of weakly bound agglomerates 30-40 nm in size. Structure evolution durin g heat treatment was studied in the range 100-1400 degrees C. Long-ran ge-order microdomains were found to form in the gel. Between 1200 and 1400 degrees C, rapid crystallization of the gel gives rise to the for mation of metastable tetragonal ZrO2. The major phases in the ceramic material prepared from the gel precursor are T, T', and T''.