THE MICROSTRUCTURE AND MECHANICAL-PROPERTIES OF SINTERED CELSIAN AND STRONTIUM-CELSIAN GLASS-CERAMICS

In this paper the capability of surface nucleated barium and strontium feldspars glass-ceramics of being sintered was investigated by means of density and porosity measurements, X-ray diffraction measurements, microscopic observations and indentation testing and the results compa red with those recorded on the corresponding bulk crystallized samples . The densification degree, higher than 95% of the theoretical density , and the favoured formation of thermally stable crystalline phases, s uch as celsian and Sr-celsian, with respect to those which present non -linear thermal expansion, hexacelsian, make sintering very useful for the production of low porosity, less than 3 vol%, materials. The micr ohardness values (470-780 Kg/mm2) and elastic modulus (57-115 GPa) of the sintered glass-ceramics, together with the refractoriness of the d eveloped phases make these systems particularly suitable for structura l applications.