The anodic behavior of copper, carbon steel and Fe-Cr-Ni alloys in 13M H
2SO
4 solutions has been investigated and the composition and the electrical resistance of corrosion products formed on these metals and alloys were examined. The results obtained suggest the possibility of anodizing composites of aluminum with these metals and alloys without causing severe attack on these metals.
Anodic polarization curves show that the breakthrough potential at the beginning of transpassivation were 47.0, 31.5, 30.5 and 26.0V for Cu, carbon steel, Al and Fe-Cr (18%)-Ni (0.2%) stainless steel and that at these potentials, thin oxide films with thicknesses of 420, 240 and 240Å are formed on these metals. In the case of Cu and carbon steel, the oxide films are covered with corrosion products, the component of which were identified by X-ray diffraction, thermogravimetric analysis and chemical analysis to be CuSO
4⋅3H
2O and CuSO
4⋅
2O for Cu and FeSO
4⋅H
2O and Fe
2 (SO
4)3·H
2O for carbon steel.
In the anodization of composites, partial current passing through aluminum decreased in the order of the Al-Cu, Al-carbon steel and Al-stainless steel. For the Al-stainless steel composites, the thickness of the oxide film on aluminum increased with decreasing area of the stainless steel and the amount of nickel in it.
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