An Impact of the Molar Ratio of Na2O/K2O on Nanomechanical Properties of Glaze Materials Containing Zirconium Oxide

In this paper the nanomechanical properties of three groups of glass-ceramic materials were measured. The materials designated from the multicomponent system: SiO2-Al2O3-CaO-MgO-Na2O-K2O and the difference between them was the molar ratio of sodium oxide to potassium oxide, equal to, respectively 5.45; 1.19; and 0.77. Zirconium oxide was added to those materials, in three different amounts (1.5; 3; 6 wt%). The obtained materials were characterized by the XRD method. The materials were also observed by means of a scanning electron microscope. The chemical compositions of amorphous and crystalline phases were analyzed by the EDS measurements. It has been discovered that the amorphous phase contains small amounts of zirconium cations, which positively affect its mechanical properties as confirmed by the results of a nanomechanical study. In addition, the presence of zirconium silicate and zirconium oxides in the phase composition improves mechanical properties. It was also shown that the molar ratio of alkali oxides (sodium oxide to potassium oxide) influences the amount of crystalline phase, i.e. mainly zirconium silicate. Sodium oxide, in contrast to potassium oxide, promotes the formation of more crystals in the analyzed materials and improves nanomechanical properties. (C) 2019 Elsevier B.V. All rights reserved.