CIESC Journal ›› 2022, Vol. 73 ›› Issue (7): 3182-3192.DOI: 10.11949/0438-1157.20220156

• Surface and interface engineering • Previous Articles     Next Articles

Effect of valence state of chromium in molten chloride salt on corrosivity of nickel-based alloy

Xiaolan WEI1(),Wenjie QI1,Jing DING2,Jianfeng LU2,Weilong WANG2,Shule LIU2   

  1. 1.School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, Guangdong, China
    2.School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510006, Guangdong, China
  • Received:2022-01-26 Revised:2022-05-04 Online:2022-08-01 Published:2022-07-05
  • Contact: Xiaolan WEI

氯化物熔盐中铬的价态对镍基合金腐蚀性的影响

魏小兰1(),戚文杰1,丁静2,陆建峰2,王维龙2,刘书乐2   

  1. 1.华南理工大学化学与化工学院,广东 广州 510640
    2.中山大学材料科学与工程学院,广东 广州 510006
  • 通讯作者: 魏小兰
  • 作者简介:魏小兰(1963—),女,教授,xlwei@scut.edu.cn
  • 基金资助:
    国家自然科学基金重点项目(52036011)

Abstract:

The corrosivity of molten chloride salt is an important factor limiting its application. Its corrosion to chromium-rich metal materials mainly results in the preferential loss of chromium from metals to molten salt. The effect of chromium valence on the subsequent corrosion of metal in molten salt is the key to understand the continuous corrosion of metal. In this paper, the effects of Cr0, Cr2+ and Cr3+ on the corrosion of a chromium-poor Hastelloy B-2 (HB-2) and two chromium-rich Hastelloy C-276 (HC-276), Hastelloy X (HX) nickel-based alloys are studied by immersion corrosion test. By analyzing the results of mass change, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), the corrosion difference of molten salts containing different valence chromium on chromium-rich and chromium-poor metals are discussed. The experimental results show that Cr0 and Cr2+ can significantly reduce the corrosion mass loss rate and inhibit their corrosion by consuming active oxides such as H2O and O2. Cr3+ can inhibit the corrosion of chromium-poor alloy HB-2, but can promote the corrosion of chromium-rich alloy HC-276 and HX. The results of SEM and XRD show that Cr3+ not only enhance the preferential loss of chromium, but also enhance the loss of Fe. The standard Gibbs free energy variation ?rGm? of oxidation of CrCl3 oxidized Ni, Cr, Fe are calculated respectively. The results show that the oxidation of Cr and Fe by CrCl3 are -142.9 kJ/mol and -87.4 kJ/mol, indicating that the reaction is carried out thoroughly. The oxidation of Ni and Mo by CrCl3 is limited. Therefore, CrCl3 in molten salt promotes the corrosion of chromium-rich alloy by oxidizing Cr and Fe in the alloy, while Cr0 and CrCl2 inhibit corrosion by consuming oxidizing species in molten salt.

Key words: molten chloride salt, chromium, corrosion, nickel base alloy

摘要:

氯化物熔盐的腐蚀性是制约其应用的重要因素,对富铬金属材料的腐蚀会导致金属中铬元素优先流失到熔盐中。探讨进入熔盐中不同价态的铬对后续腐蚀的影响,是了解熔盐长期运行中金属持续受腐蚀的关键。通过浸没腐蚀实验研究在三元NaCl-MgCl2-CaCl2熔盐中引入Cr0、Cr2+与Cr3+后,对一种贫铬Hastelloy B-2(HB-2)和两种富铬Hastelloy C-276(HC-276)、Hastelloy X(HX)镍基合金腐蚀性的影响。通过比较腐蚀前后质量变化、X射线衍射(XRD)、扫描电子显微镜(SEM)以及能谱分析(EDS)的结果,探讨含不同价态铬的熔盐对贫铬与富铬金属的腐蚀性差异。实验结果表明,Cr0和Cr2+能消耗熔盐中H2O、O2等氧化性物种,从而有效抑制腐蚀;Cr3+会抑制贫铬HB-2的腐蚀,但能促进富铬HC-276和HX的腐蚀;SEM和XRD分析结果表明,Cr3+在增强富铬金属铬优先流失的同时也会增强铁流失。热力学理论计算结果表明,CrCl3氧化Cr、Fe的反应进行得很彻底;而CrCl3氧化Ni、Mo的反应进行程度有限。因此,熔盐中含CrCl3会氧化合金中Cr和Fe从而促进富铬合金腐蚀,而含Cr0和CrCl2能降低熔盐中的氧化性物质含量而抑制腐蚀。

关键词: 氯化物熔盐, 铬, 腐蚀, 镍基合金

CLC Number: