PERFORMANCE EVALUATION OF THERMAL BARRIER COATINGS OF STRUCTURAL STEEL

Abstract

Thermal barrier coatings (TBCs) are ceramic coatings formed using detonation gun. This coating consists of nickel chromium (Ni-Cr) as bond coat and aluminium oxide (Al2O3) as top coat. Using scanning electron microscope, evaluation of the microstructure at interfaces of thermal barrier coating has been done. Micromechanical properties like microhardness, morphology, have been analysed. Thermal cycles have been done for performance evaluation of these coatings and hot corrosion behaviour has been evaluated. Thermally grown oxide layer was developed after some thermal cycles and the thickness of this layer was analysed using scanning electron microscope. Energy dispersive analysis of X-Rays used for analysing the elements present in coatings after thermal cycles. X-Ray diffraction analysis used for assessing the compounds formed and responsible for delamination of coatings. After evaluation of microstructure, hot corrosion behaviour thermal barrier coating were subjected to life prediction model for detonation gun. These results include measurements of physical and mechanical properties, interfacial oxide development attributes, thermal cycles done for life prediction and model development using graph between thermally grown oxide layer thickness and no of cycles which finally helped in estimating the life of this thermal barrier coating.