DENSIFICATION AND PROPERTIES OF CMAS GLASS-CERAMIC PREPARED FROM COMPACTS OF PRESSED POWDERS AND OF TAPE CAST POWDER MULTILAYERS

Calcia magnesia alumina silica (CMAS) glass ceramics containing anorth ite, diopside, and barium feldspars as crystalline phases have been fa bricated by uniaxial pressing of tape cast glass powder multilayers. T he sinterability of the parent glass was investigated from observation s of the densification process and the extent of crystallisation deter mined by changes in the microstructure and mechanical properties of si ntered compacts which were prepared below 1100 degrees C. The results showed that glass ceramics produced by tape casting had a higher densi ty and lower porosity than those obtained by uniaxial pressing of loos e powders. The tape cast material also showed superior mechanical prop erties, characterised by Vickers microhardness and elastic modulus, an d achieved a higher degree of crystallinity at a temperature 100 K low er than for the pressed powder samples. The low porosity (0.5-1.0%), V ickers hardness (700 HV (25 g)), and elastic modulus (125 GN m(-2)) in dicate that the sintering of multilayer tape cast glass powder is a vi able method for producing glass ceramics.