Ablation behavior of SiC whisker and ZrB2 particle filled ZrO2 sol gel composite coating under high intensity continuous laser irradiation
Abstract In this study, laser ablation resistant composite coating consisting of zirconium diboride (ZrB2) particulate and silicon carbide (SiC) whisker with zirconia (ZrO2) sol binder was prepared to meet requirements of anti laser ablation ability. Laser ablation behavior of as prepared coating was investigated under varying laser powers. Results revealed that the highest back surface temperature of coated aluminum substrate was only 150 degC when irradiated at a power density of 6.3 kW/cm2 for 10 s, which is below the maximum allowable temperature of the aluminum alloy substrate (200 degC) After ablation for 10 s, the mass ablation rate of the composite coating was 4.45 mg/s. Apparently, the composite coating exhibited outstanding ablation resistance against high intensity continuous laser irradiation. At initial stage of ablation, combination of self healing effect of liquid ZrO2 SiO2 layer and volatilization of B2O3 provide effective joint protecting mechanism. With increasing ablation time, ZrO2 ceramic barrier layer, product of the pyrolysis of ZrO2 gel and ZrB2 filler, becomes progressively more important in maintaining excellent laser ablation resistance behavior, which is normally effective at around ablation pit.