Acta Metallurgica Sinica (English Letters) ›› 2019, Vol. 32 ›› Issue (12): 1470-1482.DOI: 10.1007/s40195-019-00963-7

所属专题: 2019年腐蚀专辑-2

• • 上一篇    下一篇

  

  • 收稿日期:2019-05-27 修回日期:2019-07-29 出版日期:2019-12-10 发布日期:2019-11-25

Corrosion and Cavitation Erosion Behaviours of Cast Nickel Aluminium Bronze in 3.5% NaCl Solution with Different Sulphide Concentrations

Qi-Ning Song1(), Nan Xu1, Yao Tong1, Chen-Ming Huang1, Shou-Yu Sun1, Chen-Bo Xu1, Ye-Feng Bao1, Yong-Feng Jiang1, Yan-Xin Qiao2, Zhi-Yuan Zhu2, Zheng-Bin Wang3   

  1. 1 College of Mechanical and Electrical Engineering, Hohai University, 200 Jinling North Road, Changzhou 213022, China
    2 College of Materials Science and Engineering, Jiangsu University of Science and Technology, 2 Mengxi Road, Zhenjiang 212003, China
    3 Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016, China
  • Received:2019-05-27 Revised:2019-07-29 Online:2019-12-10 Published:2019-11-25

Abstract:

The effect of sulphide (Na2S) concentration (SC) on the corrosion and cavitation erosion behaviours of a cast nickel aluminium bronze (NAB) in 3.5% NaCl solution is investigated in this study. The results show that when the SC exceeds 50 ppm, the hydrogen evolution reaction dominates the cathodic process, and a limiting current region appears in the anodic branch of the polarisation curve due to the formation of a copper sulphide film, which is a diffusion-controlled process. After long-term immersion, the increased mass loss rate of NAB with the sulphide additions of 20 and 50 ppm is attributed to the less protective films, which contains a mixture of copper oxides and sulphides. Moreover, NAB undergoes severe localised corrosion (selective phase corrosion, SPC) at the β′ phases and eutectoid microstructure α + κIII. By comparison, NAB undergoes general corrosion and a copper sulphide film is formed in 100 and 200 ppm sulphide solutions. Cavitation erosion greatly increases the corrosion rate of NAB in all solutions and causes a negative potential shift in 3.5% NaCl solution due to the film destruction. However, a positive potential shift occurs in the solutions with SC higher than 50 ppm due to the accelerated mass transfer of the cathodic process. The cavitation erosion mass loss rate of NAB increases with the increase of SC. The occurrence of severe SPC decreases the phase boundary cohesion and causes brittle fracture under the cavitation impact. The corrosion-enhanced erosion is the most predominant factor for the cavitation erosion damage when the SC exceeds 50 ppm.

Key words: Nickel aluminium bronze, Sulphide, Corrosion, Cavitation erosion, Synergy