ABSTRACT

A CoCrFeNiMo high-entropy alloy (HEA) coating was prepared on Ti6Al4V alloy by plasma spraying technique. The microstructure and phases of the obtained coating were analysed using an ultra-depth-of-field microscope and X-ray diffraction, respectively. The electrochemical corrosion properties of CoCrFeNiMo HEA coating in 3.5% NaCl, 0.1 M H₂SO₄ and 0.1 M NaOH solutions were comparatively evaluated using an electrochemical workstation, and the corrosion mechanisms were also discussed by the corrosion models. The results show that the CoCrFeNiMo HEA coating is mainly a solid solution structure of face-centered cubic, which forms mechanical bonding at the coating interface. The charge transfer resistance R_ct of 597 × 10¹⁶ μA·cm^–2 in 0.1 M H₂SO₄ solution is the highest and the corrosion current density i_corr of 4.203 × 10^–7 μA·cm^–2 also presents the lowest among the three kinds of corrosive solutions, which shows the highest electrochemical corrosion resistance. As a result, the sequence of corrosion resistance is in 0.1 M H₂SO₄ solution > in 3.5% NaCl solution > in 0.1 M NaOH solution, in which the corrosion resistance is further improved by the passive film on the CoCrFeNiMo HEA coating.

摘要

采用等离子喷涂技术在 Ti6Al4V 合金表面制备了 CoCrFeNiMo 高熵合金 (HEA) 涂层。分别使用超景深显微镜和 X 射线衍射分析了所得涂层的微观结构和物相。利用电化学工作站对比评价了CoCrFeNiMo HEA涂层在3.5% NaCl、0.1 MH ₂ SO ₄和0.1 M NaOH溶液中的电化学腐蚀性能，并通过腐蚀模型讨论了腐蚀机理。结果表明，CoCrFeNiMo HEA涂层主要为面心立方固溶体结构，在涂层界面形成机械结合。电荷转移电阻R _ct 597×10 ¹⁶μA·cm ^–2在0.1 MH ₂ SO ₄溶液中最高，腐蚀电流密度i _corr为4.203×10 ^–7 μA·cm ^–2也是三种腐蚀溶液中最低的，表明电化学最高耐腐蚀性能。结果表明，在0.1MH ₂ SO ₄溶液中的耐蚀性顺序为>3.5%NaCl溶液中>0.1M NaOH溶液中，其中CoCrFeNiMo HEA涂层上的钝化膜进一步提高了耐蚀性。