The surface films on copper alloys has been studied by the immersion test, polarization measurement, electron diffraction analysis, infrared multiple reflection spectroscopy and photoelectron spectroscopy in 3%NaCl aqueous solution.
The results obtained are as follows:
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oindent(1) Atacamite is formed on surface of copper and copper-zinc alloys.
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oindent(2) On copper-tin alloys, SnO
2 layer is formed on the surface of alloys, atacamite and Cu
2O are produced on the SnO
2 layer.
The corrosion resistance of the alloys is due to SnO
2 or tin compound layers.
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oindent(3) On copper-aluminium alloys and copper-zinc-aluminium alloys, Cu
2O layers are formed, and layers of compound of additional alloying elements are formed on the Cu
2O layer.
The protective films of these alloys are Cu
2O layer.
The layer of compound of additional alloying elements affects the growth of the Cu
2O layer.
The surface compound of the alloys containing Al is mainly AlOOH.
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