PREPARATION OF Al?O?-CaAl??O??-ZrO? COMPOSITE CERAMIC MATERIAL BY THE HYDRATION AND SINTERING OF Ca?ZrAl?O??-REACTIVE ALUMINA MIXTURE

摘要

Ceramic material of composition belonging to the Al?O?-CaAl??O??-ZrO? compatibility field was obtained as a result of hydration and sintering of the mixture of Al?O? and Ca?ZrAl?O?? powders. The hydrated Al?O?- Ca?ZrAl?O?? mixture products were studied by XRD, DTA-TG-EGA and FT-IR after 14 days of curing and hydration at 50°C. C?AH?, Al(OH)? and CaZrO? compounds were formed upon hydration. CaZrO? and the lime-rich calcium aluminates formed as transient phases during hydration and dehydration processes were converted to CA6 and ZrO? in the presence of an excess of Al?O? during sintering at 1500°C. The Al?O?-based dense refractory composite material was investigated by XRD, FT-IR, SEM-EDS and mercury porosimetry. The sintered ceramic microstructure consists of a homogeneous distribution of zirconia grains in an alumina matrix reinforced with the calcium hexaaluminate phase. The presence of Al?O?, CaAl??O?? and ZrO? in the synthesized material was confirmed by XRD and FT-IR techniques. By applying the mercury intrusion porosimetry technique, the heterogeneous pore size distribution of the refractory composite material was determined.