SiCf/SiC表面环境障涂层的基体无损去除方法

Substrate-lossless Removal Approach of Environmental Barrier Coatings on SiCf/SiC

应用于碳化硅陶瓷基复合材料(SiCf/SiC-CMC)表面的抗水氧腐蚀环境障涂层(EBC),在高速燃气冲刷等极端环境下长期服役后出现烧蚀、局部开裂或剥落等问题。为了循环再利用价格昂贵的CMC材料,亟待发展EBC修复技术,而去除原有EBC涂层是最重要和最基础的第一步。论文在研究EBC涂层的多层复杂结构及其力学行为基础上,基于EBC与基体的力学性能差异,提出了喷砂层剥的涂层去除方法。相比于化学腐蚀、高压水冲击、激光清洗等,该方法在确保基体无损方面具有明显的优势。利用自主研制的EBC去除装置,结合涂层去除前后的表面形貌分析,探究了去除工艺参数对涂层去除效果的影响规律,实现了涂层去除并明确了基体无损伤特征,讨论了涂层去除机理。无损CMC基体的EBC去除方法,为发展整套EBC维修再制造技术提供了基础支撑。

Environmental barrier coatings(EBC)can be applied to the surface protection of silicon carbide ceramic matrix composites(SiCf/SiC-CMC)from combined corrosion of water-oxygen.Local spallation or delamination would occur after exposure to high-speed and high temperature flame ablation.In order to recycle and reuse the extremely expensive CMC materials,it is urgent to develop EBC remanufacturing technology.Removing the original failed EBC is the most important and primary step for the deposition of new EBC.In this study,a substrate-lossless removal method for the failed EBC is proposed,based on the structural and mechanical property analysis of the multi-layered EBC and substrate.Conventional methods,such as chemical corrosion,high pressure water impact,laser cleaning,are difficult to be directly applied to the removal of EBC coating due to the inevitable substrate damage.By comparing and analyzing the mechanical properties of multi-layered EBC and substrate,a selective erosive method with sandblasting was proposed.By using a self-developed EBC removal device,the effects of parameters on coating removal efficiency were investigated based on the surface morphology after removal.In addition,the non-destructive characteristics of substrate and the removal mechanism of coating were discussed.The substrate-lossless removal method of failed EBC provides fundamental support for the development of overall EBC remanufacturing technology.