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应用柠檬酸溶胶–凝胶法制备BaO–Al2O3–SiO2(BAS)溶胶,将BAS溶胶直接刷涂在碳纤维(carbon fiber,Cf)/SiC–SiC基底上制备出BAS涂层,并在1250℃,50%(体积分数,下同)H2O–50%O2和0.1MPa压力下对涂覆和未涂覆BAS涂层的样品进行腐蚀试验。用红外光谱仪、热重–差示扫描量热分析仪、X射线衍射仪、扫描电镜表征了BAS溶胶–凝胶及涂层的性能;采用电子天平、电子万能试验机对涂覆和未涂覆BAS涂层的样品耐腐蚀性能进行表征。结果表明:将pH控制在4～5,柠檬酸与金属离子Ba2+和Al3+的摩尔比分别为2和3时,可成功合成均匀、透明、稳定的BAS溶胶。BAS溶胶1次刷涂烧结的涂层厚度约为10μm,4次可达50μm左右。在1250℃的水氧耦合条件下腐蚀200h后,与未涂覆BAS的Cf/SiC–SiC比较,涂覆BAS的Cf/SiC–SiC强度保持率达88%,并且质量无明显损失。
The BaO-Al2O3-SiO2 (BAS) sol was prepared by citric acid sol-gel method and BAS coating was prepared by brushing BAS sol directly on carbon fiber (Cf) / SiC- 50% (volume fraction, the same below) H2O-50% O2 and 0.1MPa pressure on the coated and uncoated BAS coating sample corrosion test. The properties of BAS sol-gel and coating were characterized by FTIR, TG-DTA, X-ray diffractometer and scanning electron microscopy. The electronic balance and electronic universal testing machine were used to evaluate the properties of coated and uncoated The corrosion resistance of BAS-coated samples was characterized. The results show that the homogeneous, transparent and stable BAS sol can be successfully synthesized when the pH is controlled at 4 ~ 5 and the molar ratio of citric acid to metal ions Ba2 + and Al3 + is 2 and 3, respectively. BAS sol brush coating once the thickness of the coating is about 10μm, 4 times up to about 50μm. Compared with Cf / SiC-SiC uncoated with BAS, the strength retention of Cf / SiC-SiC coated with BAS was 88% after 200h etching at 1250 ℃ under the coupling of water and oxygen, and there was no significant loss of mass.