Investigation on Thermophysical and Physicochemical Properties of CaO-SiO<inf>2</inf>-CaF<inf>2</inf>-22.5%TiO<inf>2</inf> Silica Based Electrode Coating System

The present paper aims to study the thermophysical and physicochemical properties of CaO-CaF2-SiO2-22.5% TiO2 based electrode coating for welding the components of advanced ultra-supercritical power plants. The mixture design methodology was used to formulate thirteen coating mixtures to explore the effect of flux coating properties, i.e., density, change in enthalpy, weight loss, thermal conductivity, specific heat, and thermal diffusivity. Flux coating properties play an essential role in achieving better weldments. Fourier transformation and X-ray diffraction were used to analyze electrode coating composition structural behavior. The coating composition was also characterized by using a thermogravimetric analyzer and hot disc apparatus, and after that, a regression model analysis was carried out to study individual, and their interaction effects on the thermophysical and physicochemical properties. CaO.CaF2, CaO.SiO2, and CaF2.SiO2 is the most effective binary mixture which has an increasing effect on density. The weight loss of coating observed during thermogravimetric analysis is affected by individual constituents significantly. The binary interaction of SiO2.CaO and CaF2.SiO2 is the most favorable and has an increasing effect on weight loss. Individual components affect change in enthalpy significantly. The binary interaction of CaO.SiO2 and CaF2.SiO2 is the most effective and has an increasing effect on change in enthalpy. The thermal properties of coating composition observed during hot disc are affected by individual and binary mixture constituents. Binary mixture CaF2.CaO and CaF2.SiO2 is having an increasing effect on thermal conductivity. Binary mixture SiO2.CaO shows a decreasing impact on thermal diffusivity. Binary mixture constituents CaF2.CaO, SiO2.CaO is the most effective and has an increasing effect on specific heat.