摘要
目的 提高ZrB_(2)/SiC涂层的致密性及抗氧化烧蚀能力。方法 设计向ZrB_(2)/SiC涂层中掺杂TaSi_(2),以提升ZrB_(2)/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TaSi_(2)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,TaSi_(2)的加入能够增加SiO_(2)的含量,并产生热稳定性好的TaZr_(2.75)O_(8)。此外致密TaZr_(2.75)O_(8)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ZrB_(2)/SiC涂层硅化物掺杂改性方案为30%TaSi_(2)/42%ZrB_(2)/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。
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 ZrB_(2)/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.In order to improve the density and oxidation resistance of ZrB_(2)/SiC coating,TaSi_(2) was doped into ZrB_(2)/SiC coating.The introduction of TaSi_(2) can effectively supplement the silicon loss at high temperature,and the SiO_(2) generated by TaSi_(2oxidation) at high temperature can seal the cracks of the coating,prevent oxygen diffusion.In addition,the oxide of TaSi_(2) is Ta_(2)O_5,with moderate density(8.2 g/cm~3) and high melting point(1 800℃),which can reduce the volatilization of SiO_(2) at high temperature(1600 ℃),and Ta_(2)O_(5) in molten state can protect the pores of the coating,thus enhancing the oxidation re sistance of ZrB_(2)/SiC compo site coating.4 kinds of compound agglomerated powders with different compositions were prepared by spray granulation:1T64,2T64,3T64,2T73.The experimental results show that the fluidity of agglomerated powders with four different composition ratios is 62.2 s/50 g,59.0 s/50 g,56.8 s/50 g and 55.43 s/50 g,respectively.The bulk density is 5.52 g/mL,5.58 g/mL,5.66 g/mL and 5.65 g/mL.The fluidity and bulk density of the powder increased with the increase of doped TaSi_(2) content.Four kinds of agglomerated powder composite coatings were prepared on C/C substrates by APS.The results show that with the increase of TaSi_(2),the melt eutectic zone of the coatings increases and the density of the coatings improves obviously.With the increase of powder fluidity and bulk density,the deposition rate of powder also increases to a certain extent.Among them,3T64(30vol%TaSi_(2)/42vol%ZrB_(2)/28vol%SiC) coating has the best density.Oxygen-acetylene flame method is used to evaluate the ablation of the coatings.The results show that the mass loss rates of the coatings prepared by the four kinds of composite agglomerated powder with different compositions are 4.33×10^(-4)g/s,4.03×10^(-4) g/s,1.70×10^(-4) g/s and 3.13×10^(-4) g/s respectively after ablation at 1 600℃ for 300 s.the addition of TaSi_(2) can increase the content of SiO_(2) and produce TaZr_(2.75)O_8(with high thermal stability),while the production of densified TaZr_(2.75)O_(8can) effectively improve the oxidation and ablation performance of the coating.The final silicide doping modification scheme to improve ZrB_(2)/SiC coating obtained in this paper is 30vol%TaSi_(2)/42vol%ZrB_(2)/28vol%SiC.
作者
刘昌鹏
雷伟
冉旭东
张菲玥
LIU Chang-peng;LEI Wei;RAN Xu-dong;ZHANG Fei-yue(Southwest Institute of Technology and Engineering,Chongqing 400000,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2023年第10期350-359,共10页
Surface Technology
