Effect of fugitive phase addition on porosity evolution and properties of stoneware tiles

Abstract

Different percentages of fugitive phase with three different average particles were added to the green porcelain compositions. The fugitive phase was burnt out during the sintering, and the shrinkage of the samples was proportional to the added volume. The lower the particle size of the fugitive phase was, the higher the shrinkage became. The properties of stoneware tiles as apparent density, linear shrinkage, modulus of rupture, porosity, roughness and water absorption were studied as function of the added fugitive phase. A reduction of the porosity was obtained when the added fugitive phase was <5 vol.-%. The modulus of rupture improvement was found in samples with higher density. The surface roughness increased by both the volume and the particle size of fugitive phase. Large added porosity volume was effectively eliminated, and the porosity was equilibrated to a fixed value related to the initial particle size of the fugitive phase. The main mechanism that contributed to the elimination of porosity during liquid assisted sintering was the gas diffusion. Large pores were hindered by the crystalline phases, and thus pore, coalescence was avoided in the porcelain stoneware.