Effect of firing temperature on sintering of porcelain stoneware tiles

Abstract
Porcelain stoneware tile is a non-equilibrium porcelain material produced by a fast
firing process of kaolinitic clay, quartz and feldspar mixtures. This building material,
generally used in pavements and also as wall covering and ventilated façades, is
endowed with high technological properties such as low water absorption, high bending
strength and abrasion resistance and excellent chemical and frost resistance. These
properties cause that porcelain stoneware tile was actually the material with the highest
increase in production and sales over all other ceramic building material. Nevertheless,
there is a scarcity of high quality research focused on the effect of mullite growth on
technological properties of porcelain stoneware tile and on the effect of different fluxing
agents on both mullite growth and evolution of physical and technological properties
during firing. In this paper, the behaviour of a potassic porcelain stoneware body during
the firing process is investigated. A porcelain stoneware composition was prepared by
mixing 50% kaolinitic clay, 40% feldspar and 10% quartz. The samples were sintered
following a fast firing process. The sintering behaviour of the fired samples was
evaluated by linear shrinkage, water absorption and porosity measurements. Both green
powder and fired samples were characterized by means of differential thermal analysis
(DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), dilatometry and
bending strength measurements.