摘要
以Ti-45Al-2Mn-2Nb合金为基体,采用多弧离子镀制备NiCrAlY涂层、喷涂-烧结法制备搪瓷基复合涂层,对比研究了2种涂层以及合金基体的热腐蚀行为。热腐蚀实验温度为850℃,选用饱和盐溶液溶质成分为75%Na_2SO_4+25%NaCl (质量分数),涂盐量为1.5～2.5 mg/cm^2。研究结果表明,合金基体完全不具备抗热腐蚀能力,表面形成的氧化膜疏松多孔,且极易剥落;NiCrAlY涂层表面生成的保护性Al_2O_3膜提高了合金的抗热腐蚀能力,然而涂层与基体间严重的互扩散及Al_2O_3膜与熔盐的碱性溶解使得NiCrAlY涂层逐渐失效,热腐蚀60 h即出现氧化膜的剥落;而搪瓷基复合涂层在熔盐环境中只发生了轻微的物理溶解,具有极高的热稳定性及较低的热腐蚀速率,有效地阻隔了腐蚀性离子的入侵,抗热腐蚀性能优异。
TiAl intermetallic alloys have attracted great attention for its potential application in preparing low pressure turbine blades in aircraft engine. However, its poor oxidation and corrosion resistance becomes a challenge at temperatures above 800 ℃, which leads to the developing of protective coatings. Enamel coating is considered as one of the candidates that match the TiAl alloy well, meanwhile provide corrosion protection. Enamel coating has many advantages such as high thermochemical stability, adjustable thermal expansion coefficient and simple preparation process. This study comparatively investigates hot corrosion behavior of the Ti-45 Al-2 Mn-2 Nb alloy, the traditional NiCrAlY coating and the enamel based composite coating in(75%Na2SO4+25%NaCl, mass fraction) melted salt. Results indicate that after 80 h of hot corrosion, the bare alloy has completely destroyed. For the NiCrAlY coating, it protects the underlying alloy well by forming a protective Al2O3 scale initially. However, serious interdiffusion between coating and substrate results in the degeneration of the coating as well as the scale. At the same time, the basic dissolution of Al2 O3 film accelerates corrosion. So obvious spallation takes place after 60 h corrosion. The enamel based composite coating shows excellent thermal stability and low corrosion rate. During the whole hot corrosion test, it still retains its original blue glazing color and luster. Furthermore, the enamel coating suppresses the inward diffusion of oxygen and corrosive ions into the alloy substrate, and thus, it protects the TiAl alloy well from corrosion of the molten(75%Na2SO4+25%NaCl,mass fraction) salt.
作者
廖依敏
丰敏
陈明辉
耿哲
刘阳
王福会
朱圣龙
Yimin LIAO;Min FENG;Minghui CHEN;Zhe GENG;Yang LIU;Fuhui WANG;Shenglong ZHU(Shenyang National Key Laboratory for Materials Science, Northeasten University, Shenyang 110819, China;Department of Precision Manufacturing Engineering, Suzhou Institute of Industrial Technology, Suzhou 215104, China;Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2019年第2期229-237,共9页
Acta Metallurgica Sinica
基金
国家自然科学基金项目No.51471177和No.51871051
中央高校基本科研业务费专项基金项目No.N160205001
江苏省自然科学基金青年项目No.BK20160353
江苏省高校自然科学研究面上项目No.16KJB460032~~
