X-ray photoelectron spectroscopy depth-profiling analysis of surface films formed on Cu-Ni (90/10) alloy in seawater in the absence and presence of 1,2,3-benzotriazole

Abstract

X-ray photoelectron spectroscopy (XPS) depth-profiling analysis was performed to investigate the chemical composition of the film formed on Cu–Ni (90/10) alloy in seawater and sulphide-polluted seawater in the absence and presence of an inhibitor, 1,2,3-benzotraizole (BTAH). The chemical composition of the film is found to vary at different depths of the film. In seawater environment, the outermost layer is found to consist of CuO, Cu(OH)2 and Cu2O. After sputtering for 12 min, the major constituent of the film is Cu2O. In seawater polluted with sulphide also the outermost layer is found to consist of CuO, Cu(OH)2 and Cu2O without any Cu2SorCuS. After 4 min of sputtering only, the peaks due to Cu2S and CuS are detected and the major constituent of the f ilm is still Cu2O. The sulphides of copper are absent after 8 min of sputtering. In the presence of BTAH, the XPS of the film showed peaksdue to carbon and nitrogen up to 4 min of sputtering. This result reveals the presence ofthe[Cu(I)BTA]ncomplexonthealloysurfaceinbothseawaterandsulphide-pollutedseawater.Thepercentage of Cu2O is found to be muchless than thatfoundin the absence of inhibitor. In both the stated environments, in theabsenceofBTAH,theoxygenconcentrationisreducedtoasmallvalueonlyafter20minofsputtering.Whereas, in the presence of BTAH, the concentration of oxygen is reduced to a very small value after sputtering for 12 min. These results infer the protective ability of the BTAH film on Cu–Ni (90/10) alloy in both seawater and sulphide-polluted seawater even after 30 days of immersion.