C/C复合材料高熵氧化物涂层抗烧蚀性能

Ablation Resistance of High-entropy Oxide Coatings on C/C Composites

新一代高超声速飞行器热端部件服役温度不断提高,对表面防护涂层的相稳定性和抗烧蚀性能提出了更高的要求。本工作针对传统过渡金属氧化物ZrO_(2)、HfO_(2)涂层开展高熵化设计,采用高温固相反应结合超音速大气等离子喷涂制备(Hf_(0.125)Zr_(0.125)Sm_(0.25)Er_(0.25)Y_(0.25))O_(2-δ)(M1R3O)、(Hf_(0.2)Zr_(0.2)Sm_(0.2)Er_(0.2)Y_(0.2))O_(2-δ)(M2R3O)、(Hf_(0.25)Zr_(0.25)-Sm_(0.167)Er_(0.167)Y_(0.167))O_(2-δ)(M3R3O)三种高熵氧化物涂层,探究稀土组元含量对高熵氧化物涂层的相结构演变规律、相稳定性以及抗烧蚀性能的影响。M2R3O涂层和M3R3O涂层呈现优异的相稳定性和抗烧蚀性能,涂层经热流密度为2.38~2.40 MW/m^(2)的氧–乙炔焰烧蚀后仍保持物相结构稳定,未发生固溶体分解或析出稀土组元。其中M2R3O涂层循环烧蚀180 s后的质量烧蚀率与线烧蚀率分别为0.01 mg/s和–1.16μm/s,相比M1R3O涂层(0.09 mg/s、–1.34μm/s)以及M3R3O涂层(0.02 mg/s、–4.51μm/s),分别降低了88.9%、13.4%以及50.0%、74.3%,表现出最优异的抗烧蚀性能。M2R3O涂层的抗烧蚀性能优异归因于其兼具较高的熔点(>2200℃)和较低的热导率((1.07±0.09)W/(m•K)),使其有效防护内部的SiC过渡层以及C/C复合材料免受氧化损伤,避免了界面SiO_(2)相形成所导致的界面开裂。

With improvement in service temperature of thermal structural components for the new generation hypersonic aircraft,higher requirements are put forward for the phase stability and ablation resistance of the thermal protection coatings(TPCs).Carrying out high-entropy design for traditional transition metal oxide ZrO_(2) and HfO_(2) coatings,solid-phase reaction and supersonic atmosphere plasma spraying(SAPS)were applied to prepare(Hf_(0.125)Zr_(0.125)Sm_(0.25)Er_(0.25)Y_(0.25)O_(2-δ)(M1R3O),(Hf_(0.2)Zr_(0.2)Sm_(0.2)Er_(0.2)Y_(0.2))O_(2-δ)(M2R3O),(Hf_(0.25)Zr_(0.25)Sm_(0.167)Er_(0.167)Y_(0.167))O_(2-δ)(M3R3O)high-entropy oxide(HEO)coatings.The effects of rare earth content on phase structure evolution,phase stability and ablative resistance of HEO coatings were investigated.M2R3O coating and M3R3O coating possessed excellent phase stability and ablation resistance,which maintained stable phase structure after ablation by oxygen-acetylene flame with heat flux density of 2.38–2.40 MW/m^(2),without decomposition of solid solution and precipitation of rare earth components.Mass ablation rate and linear ablation rate of M2R3O coating after cyclic ablation for 180 s are 0.01 mg/s and–1.16μm/s,respectively.Compared with M1R3O coating(0.09 mg/s,–1.34μm/s)and M3R3O coating(0.02 mg/s,–4.51μm/s),the reductions of ablation rate are 88.9%,13.4%,respectively,and 50.0%,74.3%for M2R3O coatings,respectively,presenting the best ablation resistance.M2R3O coating exhibits excellent ablation resistance due to its high melting point(>2200℃)and low thermal conductivity((1.07±0.09)W/(m•K)),which effectively protects the internal SiC transition layer and C/C composites from oxidation damage,avoiding interface cracking caused by the formation of SiO_(2) phase.