Pyrolysis Behavior and Laser Ablation Resistance of PCS in Polycarbosilane Composite Coatings

For the development of high-performance laser protective coatings, this work innovatively proposes the idea of recombining PCS ablative coatings on the surface of traditional yttrium stabilized zirconia (YSZ) thermal insulation coatings.Based on the characteristics of the consumption of large amount laser energy through the decomposition of polycarbosilane (PCS) and production of high-temperature ceramic protective phases, NiCrAlY/YSZ/PCS-TiO2(YPT) and NiCrAlY/YSZ/PCS-Y2O3(YPY) coatings were prepared on the surface of Ni-based alloy by slurry method combined with atmospheric plasma spraying (APS).Based on the study of the effect of TiO2 and Y2O3 addition on the pyrolysis behavior of PCS, the laser ablation resistance of YPT and YPY composite coatings on 10.6 μm CO2 laser were systematically studied and compared with that of single layer YSZ coating.The results show that YPY and YPT composite coatings have better laser protection effect than traditional YSZ coating, because in the early stage of laser ablation, the PCS decomposition on the coating surface will consume laser energy, and the residual Y2SiO5, SiC and SiO2 phases after ablation will be deposited on the YSZ coating, forming a dense protective layer, which will continue to play a role in laser protection of the YSZ coating.YPY coating has better laser protection performance than YPT coating, because Y2O3 has higher thermal conductivity and lower coefficient of thermal expansion.Smaller temperature gradient will be produced in YPY coating, which can alleviate thermal stress.Moreover, Y2O3 participates in the pyrolysis of PCS to generate Y2SiO5 phase, which can inhibit the volume 第*