Investigation of Thermophysical and Physicochemical Characteristics of Al2O3-SiO2- CaO - Na3AlF6 Flux for SMAW Electrode Coating

Abstract

This study investigated the thermophysical, physicochemical, and electrical characteristics of electrode coatings developed for application in the weld joint of nuclear power plants (NPPs). The extreme vertices design technique has been used in this work to develop the Al2O3-SiO2-CaO-Na3AlF6-based Shielded metal arc welding (SMAW) electrodes. Twenty-six electrode coating compositions were formulated, and flux coatings were milled into a fine powder for further characterization. X-ray diffraction (XRD) technique was utilized to investigate the structure and phases of the coating composition, and the Fourier transform infrared (FTIR) analysis technique was employed to determine the nature of bonds. The coating's thermal characteristics, including conductivity, diffusivity, and specific heat, were evaluated using hot disk equipment. Enthalpy change and thermal stability of flux coating were determined using the Differential thermal analysis(DTA)/ differential scanning calorimetry (DSC) technique.. The precision inductance (L), capacitance (C), and resistance (R) (LCR) instrument was used further to examine the electrical characteristics of the flux coatings. In addition, a regression model has been developed for each coating property using statistical analysis and investigated a correlation between the properties and mineral interactions. Results reveal that the individual elements and their binary and tertiary interaction significantly influence the physicochemical, thermophysical, and electrical properties of the flux coatings.