In this study, the use of nickel fluoride tetrahydrate (NiF 2 •4H 2 O) as a surface activator and sealant at the same time for the coating of electroless nickel-phosphorus (Ni-P) on anodized aluminum alloy AA1050 is proposed. The usage of the activator resulted in more efficient deposition of Ni-P, improved adhesion properties, and increased wear and friction behavior as opposed to non-activated conditions. Scanning electron microscopy (SEM) and confocal laser microscopy (CLM) analyses of ultramicrotome-cut cross sections of Ni-P coated specimens, surface-activated by NiF 2 •4H 2 O, revealed a more well-structured metal-coating interface as opposed to non-activated conditions.

The corrosion morphology in grade 2205 duplex stainless steel wire was studied to understand the nature of pitting and the causes of the ferrite phase’s selective corrosion in acidic (pH 3) NaCl solutions at 60 °C. It is shown that the corrosion mechanism is always pitting, which either manifests lacy cover perforation or densely arrayed selective cavities developing selectively on the ferrite phase. Pits with a lacy metal cover form in concentrated chloride solutions, whereas the ferrite phase’s selective corrosion develops in diluted electrolytes, showing dependency on the chloride-ion concentration. The pit perforation is probabilistic and occurs on both austenite and ferrite grains. The lacy metal covers collapse in concentrated solutions but remain intact in diluted electrolytes. The collapse of the lacy metal cover happens due to hydrogen embrittlement. Pit evolution is deterministic and occurs selectively in the ferrite phase in light chloride solutions.

In this study, CuO-SnO 2 p-n type heterostructures were produced and tested for the degradation of methylene blue and 4-nitrophenol under visible light irradiation. CuO particles were produced in plate-like morphology using hydrothermal synthesis. SnO 2 nanofibers were obtained by electrospinning. Structural, morphological, optical and semiconducting property characterization of heterostructured CuO-SnO 2 and individual phases were performed. The photocatalytic activity was found to change depending on the amount of CuO particles in heterostructured samples. Among others, the sample with 0.35 wt.% CuO-SnO 2 showed the highest photocatalytic efficiency with a degradation rate constant ~2 h −1 . Active specie scavenger tests revealed that the decomposition reaction occurs through direct oxidation mechanism by the holes in the valence band of SnO 2 in pure samples whereas in CuO-SnO 2 samples • O − 2 and • OH radicals also form and involve in the reactions. Further, the photocatalytic degradation mechanism was revealed using relative band potentials and p-n junctions of the heterostructured photocatalyst.