聚碳硅烷基复合涂层PCS裂解行为及其抗激光烧蚀性能

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

针对高性能激光防护涂层的开发问题,根据聚碳硅烷(PCS)裂解时会消耗大量激光能量,并产生高温陶瓷保护相的特点,本研究创新性地提出在传统氧化钇稳定氧化锆(YSZ)隔热涂层表面再复合PCS烧蚀型涂层的防护思路,采用料浆法结合大气等离子喷涂技术(APS)在Ni基合金表面分别制备了NiCrAlY/YSZ/PCS-TiO_(2)(YPT)和NiCrAlY/YSZ/PCS-Y_(2)O_(3)(YPY)涂层。在研究TiO_(2)和Y2O3添加相对PCS裂解行为影响的基础上,系统研究了YPT和YPY复合涂层对10.6μm CO_(2)激光器的抗激光烧蚀性能,并与单层YSZ涂层进行比较。结果表明,YPY和YPT复合涂层比传统YSZ涂层的激光防护效果更好,这是因为在激光烧蚀初期,涂层表面的PCS裂解会消耗激光能量,且烧蚀后残余的Y_(2)SiO_(5)、SiC和SiO_(2)相会沉积在YSZ涂层上,形成致密的保护层,继续对YSZ涂层进行激光防护。YPY比YPT涂层激光防护性能更好,这是因为Y_(2)O_(3)具有高热导率和低热膨胀系数,YPY涂层产生的温度梯度更小,从而缓解热应力,且Y_(2)O_(3)参与PCS的裂解生成了Y_(2)SiO_(5)相,比TiO_(2)更能抑制PCS裂解引起的体积膨胀。此外YPY涂层中心烧蚀温度更高,生成PCS裂解产物SiC和SiO_(2)相的速度更快,能及时保护下方涂层,表现出更好的抗激光烧蚀性能。该研究有望为新型抗激光复合涂层的设计提供研究思路。

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 characteristics of the consumption of large amount laser energy through decomposition of polycarbosilane(PCS)and production of high-temperature ceramic protective phases,NiCrAlY/YSZ/PCS-TiO_(2)(YPT)and NiCrAlY/YSZ/PCS-Y_(2)O_(3)(YPY)coatings were prepared on the surface of Ni-based alloy by slurry method combined with atmospheric plasma spraying(APS).Based on the effect of TiO_(2)and Y_(2)O_(3) addition on the pyrolysis behavior of PCS,the laser ablation resistance of YPT and YPY composite coatings on 10.6μm CO_(2)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 can consume laser energy,and the residual Y_(2)SiO_(5),SiC and SiO_(2)phases after ablation can be deposited on the YSZ coating,forming a dense protective layer,which can continue to play a role in laser protection of the YSZ coating.YPY coating has better laser protection performance than YPT coating,because Y_(2)O_(3)has higher thermal conductivity and lower coefficient of thermal expansion.Smaller temperature gradient can be produced in YPY coating,which can alleviate thermal stress.Moreover,Y_(2)O_(3)participates in the pyrolysis of PCS to generate Y_(2)SiO_(5)phase,which inhibits more volume expansion in PCS pyrolysis than that in TiO_(2).In addition,the core ablation temperature of YPY coating is higher,and the formation of PCS pyrolysis products SiC and SiO_(2)phase is faster,which can timely protect the lower coating,showing better laser ablation resistance.This study is expected to provide a new idea for the design of novel laser resistant composite coatings.