Thermal damage and ablation behavior of plasma sprayed Ba₂SmTaO₆ coatings irradiated by high power continuous laser

Ba₂SmTaO₆ laser protection coatings of ≈200 ​μm thickness were deposited onto stainless steel surfaces by air plasma spraying, and the laser irradiation resistance of the coatings was investigated. For laser irradiation with a laser power density less than 1000 ​W/cm², the coatings kept intact. For a laser power density exceeding 1500 ​W/cm², the Ba₂SmTaO₆ coatings underwent recrystallization, grain growth occurred, and certain spray morphology features disappeared by melting. In the case of a laser power density of 2000 ​W/cm² applied for 10s, the incident laser parameter was beyond the coatings protection threshold, and the coating peeled off. The samples back surface temperature kept unchanged within the first 1s of laser irradiation, indicating that Ba₂SmTaO₆ coatings have excellent laser protection capability and can limit the rise of the substrate temperature. However, the low thermal conductivity of Ba₂SmTaO₆ leads to a detrimental laser energy concentration at the beginning of the laser irradiation period on the sample front surface, resulting in a rapid increase of the surface temperature up to the melting point.