Preparation and Numerical Simulation Investigation of High Reflectance Anti-laser-ablation Coating

An anti-laser-ablation coating using TiO2 as pigment and potassium silicate as binder (abbreviated as KS-T) was deposited on the aluminum alloy substrate by an air spray process. Factors influencing the reflectance of KS-T coating, including particle size, pigment volume concentration and coating thickness, were investigated. The reflectance of prepared KS-T coating could be up to 96.8% at the laser wavelength of 1064 nm. A three-dimensional finite element model based on the heat-conduction equation was developed to simulate the distribution of transient temperature filed. By monitoring the temperature variation at the backside center of aluminum alloy substrate during laser irradiation and comparing with the simulation results, it is found that KS-T coating could effectively protect the substrate from laser ablation. The simulation results demonstrated reflectance decrease of samples after a period of irradiation. The possible reasons for the reflectance decrease were proposed. The calculation results also showed that an obvious temperature drop emerged at the coating/substrate interface when interface thermal resistance (ITR) was considered. Eventually heat flux was prevented from flowing to the substrate and aluminum alloy kept a low temperature.