Evaluation of Pumice in Glaze Compositions for Ceramics

Abstract

Pumice, identified as amorphous aluminium silicate, occurs as a result of volcanic activity and is a porous, spongy, volcanic, glassy rock that resists physical and chemical degradation. It is considered to be glass because it has no crystal structure. The use of pumice as a fluxing agent instead of feldspar frit in stoneware and wall tile glaze compositions was investigated. Using a standard glaze recipe, glazes with different amounts of pumice, and thus different colour, brightness and Vickers hardness values, were prepared. Their particle size distributions, thermal microscopy behaviour, dilatometer and Rietveld X-ray diffraction (XRD) results were evaluated. The formation of new phases and microstructural changes that occurred in the formulations were also investigated via XRD, scanning electron microscopy and energy-dispersive X-ray analyses. On the basis of these analyses, it was determined that, using pumice, low-cost wall tile and stoneware glaze formulations that have the required performance properties can be developed.

Keywords: Pumice, glaze, flux, wall tile, stoneware.