Toward improving the reflectivity of ablative heat-insulating coating under high-energy laser irradiation

Abstract: Anti-laser damage has become a major concern because of the rapid evolution of high power continuous-wave laser technology. While phenolic matrix composite coatings exhibit good anti-laser property, they show low reflectivity during laser irradiation, resulting in high energy absorption. A novel composite coating that consists of Al(OH)₃ and nano-copper fillers with phenolic resin matrix has been designed to solve the low reflectivity problem. X-ray diffraction reveals that Al₂O₃ particles generate on the surface of the coating during laser irradiation because of the dehydration reaction of Al(OH)₃. The endothermic effect of this dehydration reaction and the transpiration of nano-copper particles have a significant cooling effect on the coating. The reflectivity of coating is monitored in real time during laser irradiation. It is confirmed that the reflectivity gradually increases with the accumulation of Al₂O₃ particles. According to the temperature of back-surface substrates, the improved reflectivity does lead to a better anti-laser property of the coating. The laser ablation behavior of the composite coating was studied in detail through different laser parameters. The results show that both laser power density and irradiation time have effect on the micro-morphologies and reflectivity of the coating. Graphic abstract: [Figure not available: see fulltext.]