Influence of body composition on the technological properties and mineralogy of stoneware: A DOE and mineralogical–microstructural study

This paper reports a systematic and comprehensive investigation of the effects of the starting mixture composition on the mineralogy and propertiesof porcelain stoneware tiles using mixture design and full quantitative phase analyses by the Rietveld method. Functional relationships betweenproperties and the raw material mixture proportions were obtained and related to the mineralogical composition of the fired product. Mullitecrystallisation depended on the chemical environment. Dissolved quartz mounted to 10 wt% of the dry body regardless on initial amount, indicatingsaturation of the surrounding melt. The paramount role of the amorphous content on the stoneware properties was disclosed quantitatively. Openporosity decreased with increasing amount of amorphous content, and consequently both the stain and wear resistance increased. The CIE-Labcolour parameters a* and b* increased with increased amorphous content due to interaction with surface iron in hematite. The mullite contentincreased wear resistance, thus supporting the mullite strengthening theory.