TaSi2改性ZrB2/SiC复合粉末制备及涂层抗氧化性能研究

目的 提高ZrB2/SiC涂层的致密性及抗氧化烧蚀能力。方法 设计向ZrB2/SiC涂层中掺杂TaSi2，以提升ZrB2/SiC涂层的致密度和抗氧化性能。首先通过喷雾造粒法制备了4种不同成分配比的复合团聚粉，然后采用大气等离子喷涂(APS)在C/C基体表面制备了4种团聚粉复合涂层，最后使用氧-乙炔火焰法对所制备的涂层进行了烧蚀考核。结果 通过涂层致密度对比发现，随着TaSi2的增加，涂层共晶区会有所增加，涂层致密度得到了明显改善。通过烧蚀考核发现，TaSi2的加入能够增加SiO2的含量，并产生热稳定性好的TaZr2.75O8。此外致密TaZr2.75O8的产生还能够有效改善涂层的抗氧化烧蚀性能。结论 最终得出的ZrB2/SiC涂层硅化物掺杂改性方案为30%TaSi2/42%ZrB2/28%SiC(体积分数)大气等离子喷涂制备的抗氧化烧蚀涂层，其在1 600 ℃烧蚀5 min后的质量损失率为?1.70×10^?4 g/s。

Preparation of ZrB2/SiC Composite Powder Modified by TaSi2 and the Antioxidant Property of Its Coating

Because of its excellent performance, hypersonic vehicle has become the commanding point of military strategy and technology of military powers. C/C composites with high strength, light weight and good seismic performance have attracted wide attention. C/C composites not only have good electrical conductivity, thermal conductivity and light weight characteristics, but also have good friction resistance, high temperature resistance, thermal shock resistance and corrosion resistance, especially because of their excellent high temperature mechanical properties, so they become one of the ideal materials for hypersonic aircraft. However, due to the complex service environment of hypersonic vehicle (high temperature, water and oxygen environment), oxidation and ablation of C/C composites under high temperature and aerobic conditions have become the bottleneck of its wide application. The preparation of ZrB2/SiC coatings on C/C composites by atmospheric plasma spraying (APS ) is one of the effective methods to improve the anti-oxidation ablation performance and prolong the service life of C/C composites. However, the coatings still have some shortcomings such as difficult densification, low emissivity and fast heating rate, so they cannot be widely used.