Whiteness improvement of porcelain tiles incorporated with anorthite and diopside phases

In recent years, porcelain tiles have been increasingly used as an alternative to natural stone and marble. Moreover, the expectation of the development of more white porcelain tile bodies is also increasing. The aim of the present study is to develop ultra-white porcelain tile compositions which have significantly higher whiteness value (L* > 90) than the standard super-white porcelain tile composition because of diopside and anorthite crystallization during sintering. For this purpose, a frit which is crystallizing to diopside was used in the new composition in the present studies. Firing shrinkage, water absorption and color values (L*, a, b) of the compositions were measured. Thermal expansion coefficient values of the bodies were determined by a dilatometer; the sintering behaviors were evaluated using a double-beam non-contact optical dilatometer (ODHT). The phase analyses of the fired bodies were achieved using XRD. Microstructural analyses were carried out with SEM. According to the results, ultra-white porcelain tile compositions which are suitable for production conditions could be developed. With an industrial perspective, the other important findings are that these compositions have lower firing shrinkage and lower thermal expansion coefficient than the standard porcelain tile formulation. This provides a wide working range in terms of pressing and production by preventing the deformation problems and reducing the risk of thermal shock.