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 compared 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, such 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 microhardness values (470–780 Kg/mm2) and elastic modulus (57–115 GPa) of the sintered glass-ceramics, together with the refractoriness of the developed phases make these systems particularly suitable for structural applications.