Abstract: In order to improve the high-temperature oxidation resistance of SiC aerogel materials,a ceramic slurry was prepared by mixing ZrB₂ powder and silica sol at a mass ratio of 7∶3.The slurry was then coated on the surface of the SiC aerogel using the dip-coating method.After heat treatment at 400 ℃ for 2 h,an anti-oxidation ZrB₂ ceramic coating was obtained.The prepared coating materials were heat-treated at 600,800,1 000 and 1 200 ℃ for 2 h,respectively,and the compressive strength and oxidation resistance were investigated.The results show that the ZrB₂ coating can provide effective anti-oxidation protection for the SiC aerogel.In the initial stage of oxidation,a continuous and dense B₂O₃ glassy liquid phase layer is formed.With the temperature rising,ZrSiO₄,which is generated by the reaction between the two oxidation products SiO₂ and ZrO₂,can fill the pores formed by the volatilization of B₂O₃ in the coating,effectively improving the oxidation resistance of the material.The compressive strength of the ZrB₂/SiC aerogel composite increases with the temperature rising,reaching a maximum of 0.82 MPa at 1 200 ℃ and performing the best oxidation resistance.

Key words: ZrB₂ ceramic coating, SiC aerogel, slurry dipping method, compressive strength, oxidation resistance

摘要： 为提高SiC气凝胶材料的高温抗氧化性能,将ZrB₂粉末与硅溶胶以7∶3的质量比配制陶瓷浆料,采用浸蘸法涂覆在SiC气凝胶表面,400 ℃保温2 h得到了ZrB₂抗氧化陶瓷涂层,对制备得到的涂层材料分别在600、800、1 000和1 200 ℃保温2 h热处理,研究了试样的耐压强度和抗氧化性能。结果表明:ZrB₂涂层可为SiC气凝胶提供有效的抗氧化防护。氧化初期形成连续致密的B₂O₃玻璃液相层;随热处理温度升高,两种氧化产物SiO₂与ZrO₂反应生成的ZrSiO₄可封填涂层中B₂O₃挥发产生的孔洞,有效提高材料抗氧化性能。含ZrB₂涂层的SiC气凝胶材料的耐压强度随热处理温度升高而增大,在1 200 ℃时最大,为0.82 MPa,此时的抗氧化性最好。

关键词: ZrB₂陶瓷涂层, SiC气凝胶, 料浆浸蘸法, 耐压强度, 抗氧化性能