(南京航空航天大学 材料科学与技术学院，南京 210016)
摘 要: 采用双辉等离子表面渗铬和后续多弧离子镀铝处理在TC21合金表面制备Al-Cr涂层；同时研究Al-Cr涂层在850 ℃下的高温氧化行为和850 ℃下25%NaCl+75%Na2SO4(质量分数)混合盐中的热腐蚀行为。结果表明：Al-Cr复合涂层包括表面富Al沉积层、中间Al-Cr扩散层和内侧Cr-Ti互扩散层。在850 ℃氧化100 h后，Al-Cr涂层表面生成致密Al2O3膜，对基体有很好的保护作用；中间Al-Cr扩散层中Cr元素的存在促进Al的选择性氧化，有利于涂层的后续氧化行为。在850 ℃混合熔盐中腐蚀100 h后，内部Cr-Ti扩散区仍保持完整，涂层表现出较好的热腐蚀抗力。
关键字: TC21合金；Al-Cr涂层；双辉等离子表面冶金；多弧离子镀铝；高温氧化；热腐蚀
（School of Material Science and Technology, Nanjing University of Aeronautics and Astronautics,
Nanjing 210016, China）
Abstract:Cr+Al-type(Al-Cr) composite coating was prepared by double glow plasma surface chromizing on TC21 substrate followed by multi-arc ion aluminizing. The oxidation behaviors of Al-Cr coating in air and in mixed salt (25%NaCl+75%Na2SO4, mass fraction) at 850 ℃ were tested, respectively. The results demonstrate that Al-Cr coating consists of an outer layer of Al-rich deposition, an intermediate Al-Cr diffusion layer and an inner Cr-Ti mutual diffusion zone. After oxidation at 850 ℃ for 100 h, a dense Al2O3 oxide layer forms in the external oxide film, which provides protection for the substrate. As for the Al-Cr diffusion layer, the presence of Cr can promote the selective oxidation of Al, which is beneficial for improving the oxidation resistance. After 100 h exposure in mixed salt at 850 ℃, the inner Cr-Ti mutual diffusion zone is still integrated, indicating that Al-Cr coating has relatively good hot corrosion resistance.
Key words: TC21 alloy; Al-Cr coating; double glow plasma surface metallurgy; multi-arc ion aluminizing; oxidation; hot corrosion
