White sintered glass-ceramic tiles with improved thermal insulation properties for building applications

In order to provide a thermal barrier in an arid environment, highly reflective coatings were deposited on porous substrates made of natural raw materials from Saudi Arabia. Although highly reflective coatings inhibit heat absorption from the incoming sunlight, the body of conventional ceramic tiles warms up to environmental temperature through conduction, convection and radiation. A strategy to reduce the penetration of this heat into the building is to use a highly porous substrate, which reduces the thermal conductivity of the tile, coupled with a highly reflective glaze. The approach leads to the concept of "cool" tiles, aimed at improving the thermal efficiency of buildings. The present paper provides a first example, based on layered wollastonite-hardystonite glass-ceramics developed by double pressing of glass powders and additives followed by sinter-crystallization