Strontium carbonate in glazes from the SiO2–Al2O3–CaO–MgO–Na2O–K2O system, sintering and surface properties

Abstract

In this study, the influence of the addition of SrO on sintering and selected parameters of the surface of the glazes from the SiO2–Al2O3–CaO–MgO–Na2O–K2O system were examined. The novelty is introducing strontium oxide through strontium carbonate without using frits, which lowers the cost of the raw material input. To describe the sintering process the most important techniques were used, i.e. differential scanning calorimetry DSC, dilatometric measurements DL, hot-stage microscopy HSM, and viscosity as a function of temperature (VFT equation). Additionally, based on the data from DSC measurements, tests of the phase composition were carried out at temperatures at which thermal effects occurred. The crystal phase of Sr-feldspar is observed right after the SrCO3 decarbonization, but after the entire firing cycle, its quantity is below the XRD detection threshold. The glaze containing 7.5 mol% addition of SrO is completely amorphous. In order to examine surface physicochemical properties, laser confocal microscopy and spectrophotometry were used. An important conclusion is that the use of strontium carbonate does not cause a visual deterioration of the surface quality of the fired material.

Keywords

• Sintering
• Microstructure-final
• Surface
• Strontium carbonate