(1. 青海大學(xué) 青海省高性能輕金屬合金及深加工國(guó)家地方聯(lián)合工程研究中心，西寧 810016； 2. 青海大學(xué) 青海省新型輕合金重點(diǎn)實(shí)驗(yàn)室，西寧 810016)
摘 要: 通過純Co及代表性的Co基合金GH5188和GH6159在520 ℃熔融NaCl-52%MgCl2(摩爾分?jǐn)?shù))中的腐蝕行為研究，揭示Co基合金在熔融氯化鹽中的腐蝕機(jī)理。結(jié)果表明：3種試樣的腐蝕動(dòng)力學(xué)曲線近似滿足線性規(guī)律。腐蝕20 h后的掃描電鏡分析表明，純Co試樣表面形成了殼層結(jié)構(gòu)；EDS及XRD分析表明，殼層成分主要為MgO，這在一定程度上起到了減緩腐蝕的作用。GH6159表面也出現(xiàn)類似殼層結(jié)構(gòu)，GH5188表面有孔洞出現(xiàn)；腐蝕160 h后，GH5188表面出現(xiàn)大量互相連通的腐蝕孔洞。橫截面EDS分析表明，Co和Cr的含量均明顯降低。因此，Co基合金的腐蝕機(jī)理主要源于合金元素Cr 、Fe和Co等的氧化、溶解和揮發(fā)。
關(guān)鍵字: 熔融鹽；腐蝕；Co基合金；NaCl-52%MgCl2
（1. Qinghai Provincial Engineering Research Center of High Performance Light Metal Alloys and Forming, Qinghai University, Xining 810016, China; 2. Qinghai Provincial Key Laboratory of New Light Alloys, Qinghai University, Xining 810016, China）
Abstract:In order to explore the corrosion mechanism, the corrosion behaviour of two common Co-based alloys GH5188 and GH6159 immersed in high temperature NaCl-52%MgCl2 (mole fraction) molten salt for 160 h was measured. The results show that the corrosion kinetics curves are approximately linear. After being corroded for 20 h, there is a shell emerging on the surface of pure Co as well as GH6159 samples, which slows down the corrosion rate to some extent. Meanwhile, a lot of pores form on the surface of GH5188. And after being corroded for 160 h, these pores grow up and link together. The cross-section EDS analysis of GH5188 shows a decrease of Cr and Co content in the corrosion layer. Therefore, the mechanism of Co-based alloys is oxidation and dissolution of Cr, Fe and Co followed by volatilization of metal chloride.
Key words: molten salt; corrosion; Co-based alloy; NaCl-52%MgCl2
