Fabrication of Ceramic Composites by Microwave Sintering

To prepare 0.5LaPO4–0.5ZrO2 and 0.5LaPO4–0.5Y2O3 ceramic composites, a microwave assisted sol-gel procedure for the synthesis of nanosized 0.5LaPO4·nH2O–0.5ZrO(OH)2 and 0.5LaPO4· nH2O–0.5Y(OH)3 precursor powders was developed. Ceramic composites were prepared by microwave sintering of powders at 1100°C after preliminary heat treatment of precursor powders at 850°C, as well as by conventional stepwise sintering at 1000, 1100 and 1200°C for 24 h. The unit cell parameters of monoclinic LaPO4 were calculated depending on sintering method and temperature. The values of specific surface area of the samples, Vickers microhardness, and thermal conductivity were determined; fracture surface of ceramic samples was studied. Such a complex study of 0.5LaPO4–0.5ZrO2 and 0.5LaPO4–0.5Y2O3 composites is presented for the first time. The influence of sintering method, temperature and addition of zirconia and yttria to LaPO4 on the resulting composite’s properties, phase composition and type of ceramic fracture surface is discussed.