Behavior of CuP and OFHC Cu anodes under electrodeposition conditions

Films formed on CuP (with 0.05 wt % P) and OFHC Cu anodes in electroplating solutions were studied by X-ray Photoelectron Spectroscopy, X-ray Absorption Spectroscopy, electrochemical methods, and a newly developed gravimetric technique. The black film formed on CuP in Cl-containing solutions was found to resemble a porous sponge composed of CuCl but laden/with concentrated CuSO{sub 4} solution. The difference between the buoyancy-corrected measured mass change and the charge-equivalent mass change was found to have two components: a reversible part that comes and goes as the current is turned on and off, and an irreversible part that remains on the surface and increase in mass with time. The irreversible part results from the anodic film, which increases linearly with charge density but independent of current density. The reversible part of the mass change arises from the weight of the diffusion layer. In contrast to CuP, OFHC Cu releases much more Cu{sup +1} during anodic polarization and forms a poorly-adherent anodic film that is considerably heavier than the black film for a given charge density

In situ XANES study of the valence state of chromium during electrochemical polarization of AlCr alloys

The chemistry of chromium in the passive film on pure chromium and sputtered AlCr thin films has been studied in situ in an electrochemical cell under potential control using XANES. Depending on the rate of potential increase, the 6-valent chromium can dissolve from the alloy or be trapped in the passive film where it is electroactive i.e. the valence state can be reversibly switched between the 3- and 6-valent states by switching the applied potential. The kinetics of these processes were investigated