Nanocrystalline Non-Alkali Glass Ceramics

Nanocrystalline glass ceramics with high elastic modulus and moderate strength and toughness can be produced from a wide area in the SiO2-Al2O3-MgO-ZnO-TiO2 system. Phase assemblages include those based primarily on spinel crystals as well as those based on enstatite and spinel;common accessory phases include Mg-petalite, Mg,Al-titanite solid solutions, quartz solid solutions and rutile. These glass ceramics can have ultra-fine grain sizes, with spinel crystals less than 25nm and enstatite crystals less than 100nm in size. Such nanocrystalline microstructures are unique in the case of an enstatite glass-ceramic and provide extremely smooth polished surfaces, with average roughness of about 0.5-1.0nm.