Application of fractal dimension to optimum deposition of NiCrAlY coating by D-gun spray

Abstract

NiCrAlY coatings were fabricated by detonation gun (D-gun) spray under several process conditions to examine process optimization. The spray processes were adjusted by altering the composition of the mixed C2H2/O-2 fuel gas, and a higher fuel temperature was obtained by increasing the ratio of C2H2 to O-2. To reduce complexity for process optimization, an attempt to apply fractal dimension (FD) to the quantitative description of the splat patterns for each process was performed. The results indicated a fully melted splat usually had a larger FD, which coincided with the process conditions of dense and adhesive coating deposition. The FDs were verified to be sensitive and efficient for D-gun spray process optimization, based on the analytical results of the coating microstructures and fractured morphologies.