Cobalt-based alloys are extensively used in orthopedic applications for joint replacements due to their wear and corrosion resistance. Corrosion, however, is often associated with fatigue failure in these orthopedic devices. In this study, the effect of boron addition on the corrosion behavior of CoCrMo alloys was studied using linear polarization resistance, potentiodynamic polarization curves, electrochemical impedance spectroscopy, and cyclic voltammetry. The samples were analyzed under as-cast and heat treatment conditions after 21 days of immersion in phosphate-buffered saline (PBS) solution at 37 °C. The boron addition increased the particle content, while the heat treatment promoted enlargement and even distribution of the precipitates throughout the structure. The corrosion resistance was improved by both boron and heat treatments. The best performance was observed for a heat-treated alloy having a very small amount of boron, which had an increased resistance to corrosive attack. Such behavior was attributed to the homogenized microstructure achieved by boron and heat treatment that helped to form a stable passive layer of chromium oxide which endured the 21 days of immersion.
Photoelectrochemical water splitting (UV-Vis, 2.5 V) from alkaline solution containing cyanide was evaluated in a conventional two-compartment electrochemical cell by using Bi 2 MNbO 7 (M = Al, Fe, Ga, In) films on AISI/SAE 304 stainless steel as photoanode and a silver plate as cathode. The films were prepared by sol-gel dip-coating followed by a thermal treatment at 500°C. They were characterized by scanning electron microscopy, X-ray diffraction and energy dispersive X-ray fluorescence. During the photoelectrochemical process, both circulating current and hydrogen production were measured. Changes in cyanide concentration were determined by potentiometric titration. The activity of Bi 2 MNbO 7 films was higher or equivalent than that of TiO 2 film and dependent on the electrolyte composition and concentration. The obtained results make further work on the subject very encouraging.
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