Glass-ceramic glazes for ceramic tiles: a review

Glass-ceramics are ceramic materials produced through controlled crystallisation (nucleation and crystal growth) of a parent glass. The great variety of compositions and the possibility of developing special microstructures with specific technological properties have allowed glass-ceramic materials to be used in a wide range of applications. One field for which glass-ceramics have been developed over the past two decades is that of glazes for ceramic tiles. Ceramic tiles are the most common building material for floor and wall coverings in Mediterranean countries. Glazed tiles are produced from frits (glasses quenched in water) applied on the surface of green tiles and subjected to a firing process. In the 1990s, there was growing interest in the development of frits that are able to crystallise on firing because of the need for improvement in the mechanical and chemical properties of glazed tiles. This review offers an extensive evaluation of the research carried out on glass-ceramic glazes used for covering and pavement ceramic tile is accomplished. The main crystalline phases (silicates and oxides) developed in glass-ceramic glazes have been considered. In addition, a section focused on glazes with specific functionality (photocatalytic, antibacterial and antifungal activity, or aesthetic superficial effects) is also included.