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先采用熔模铸造中的制壳工艺,在壳型内壁制备了Si-Zr-B基底涂层Z,然后利用溶胶凝胶原 理,经浸涂-分级热处理以及850℃玻璃化热处理后,在Z表面制备了七层与Z同成分的Si-Zr-B玻璃 薄膜涂层.XRD和SEM分析结果表明,H_3BO_3的加入起抑制Si-Zr-B涂层析晶及对涂层表面裂纹 的高温自愈合作用.因此,将Z-R壳型置于1500℃保温30min后,涂层的析晶量仅为1%~3%,其结 构在高温下具有很强的稳定性.过冷实验结果表明,DD3单晶高温合金可以在该涂层壳型内获得140K 过冷度,证明Si-Zr-B涂层具有良好的非催化形核惰性.
Si-Zr-B base coating Z was prepared on the inner wall of the shell by means of the shell-making process in investment casting. Then, after sol-gel-graded heat treatment and vitrification treatment at 850 ℃, The surface of the Si-Zr-B glass thin-film coating with seven layers and the same composition of Z was prepared. The results of XRD and SEM showed that addition of H_3BO_3 could inhibit the crystallization of Si-Zr-B coating and self-healing of the surface cracks on the coating. Therefore, after the Z-R shell is placed at 1500 ℃ for 30min, the crystallization of the coating is only 1% ~ 3%. Its structure has strong stability under high temperature. The results of subcooling experiments show that the DD3 single crystal superalloy can obtain undercooling of 140K in this coating shell, proving that the Si-Zr-B coating has good non-catalytic nucleation inertness.