Effect of parameters on adhesion strength for slurry spray coating technique

Abstract

ABSTRACTIn this article, slurry spray technique (SST) has been adopted for depositing mullite–nickel based environmental barrier coatings (EBCs) on some ASTM 1018 low-carbon steel. Considerable value of adhesion strength of a deposited cermet is critical for the coating to comply with service condition. The effect of identified process parameters like stamping pressure, fly ash content, sintering additive, sintering time, and sintering temperature on optimizing adhesion strength is evaluated. Parametric assessment of the developed coatings is done utilizing Taguchi L18 orthogonal array and analysis of variance (ANOVA). Based on the analytical study of the experimentation, the dependence of adhesion strength of slurry sprayed coatings on the process parameters has been studied. Maximum adhesion strength value of 18.15 MPa was attained during experimentation within the range of the selected control parameters. The enhanced adhesion strength was found for increased sintering temperature up to 950°C which may be attributed to the improved sintering of mullite mixed fly ash due to lowering of secondary mullitization temperature. Furthermore, it has been proven experimentally that the quality of coatings achieved in this work is acceptable and approaching to the quality of thermal coatings manufactured with commercially available fabrication methods.