The effect of SiO2/Al2O3 ratio on the structure and microstructure of the glazes from SiO2–Al2O3–CaO–MgO–Na2O–K2O system

• The effect of the SiO2/Al2O3 ratio on structure of ceramic glazes were examined.
• The highest SiO2/Al2O3 molar ratio leads to dominance of the OSiO bands.
• With the highest SiO2/Al2O3 ratio crystallization of diopside was detected.
• The lowest SiO2/Al2O3 molar ratio leads to dominance of SiOAl and SiOSi bands.
• With the lowest molar ratio crystals of gahnite occurs – other glazes are amorphous.

Ceramic glazes are commonly used to covering of the facing surface of ceramics ware. A well-chosen oxide composition and firing conditions of glazes causes significant improvement of technical parameters of ceramic products. Modern glazes are classified as glass–ceramic composites with different crystalline phases arising during firing. The presence of crystals in the glass matrix is influenced by many factors, especially by oxides molar composition. A crucial role is played by the molar ratio of SiO2/Al2O3. In this work the six composition of glazes from SiO2–Al2O3–CaO–MgO–Na2O–K2O system were examined. The only variable is the ratio of the silicon oxideto alumina at a constant content of other components: MgO, CaO, K2O, Na2O, ZnO. In order to determine the real phase composition of the obtained glazes research on fluorescence spectrometer (XRF) were done. For structural studies X-ray diffraction (XRD) and spectroscopic in the middle infrared (MIR) were performed. In order to determine the state of the surface (microstructure) research on the scanning electron microscope (SEM) with EDX. The research allowed to determine the influence of SiO2/Al2O3 ratio on the structure and phase composition of glazes and the nature, and type of formed crystalline phases.

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