Influence of concentration of hydrochloric acid solutions on the passivation beh

2019-06-07 23:21:56

alloys corrosion HCl tungsten rich

责任者: Bhattarai, J.;Akiyama, E.;Habazaki, H.;Kawashima, A.;Asami, K.;Hashimoto, K. 单位: Tohoku Univ, Sendai, Jpn 来源出处: Corrosion Science,1998,40(11):1897-1914 摘要: Nano-crystalline single phase bcc solid solution of sputter-deposited tungsten-rich W-Nb alloys are passivated spontaneously in all hydrochloric acid solutions examined, and their corrosion rates are dependent upon the concentration of HCl solutions at 30 °C. The corrosion rate of the tungsten-rich W-Nb alloys in 12 M HCl is lower than that in 6 M HCl, although the initial corrosion rate measured for less than about 24 h in 12 M HCl is higher than that in 6 M HCl. XPS and AFM results reveal that the more aggressive nature of 12 M than 6 M HCl solution enhances fast formation of more stable and protective passive films, consisting of tungsten-rich double oxyhydroxide of tungsten and niobium ions due to fast dissolution of niobium. This is responsible for higher corrosion resistance in 12 M HCl than that in 6 M HCl solution at 30 °C. 关键词: Passivation;Hydrochloric acid;Tungsten alloys;Sputter deposition;Protective coatings;Corrosion resistant alloys;Composition effects;Dissolution;X ray photoelectron spectroscopy;Atomic force microscopy;Protective passive films