Structure and chemical and phase composition of the thermal oxidation products of Ni-Mo-B coatings plated by chemical catalytic reduction

Morphology, phase composition, and chemical state of the elements in the superficial oxide layers on Ni-Mo-B alloy coatings obtained by chemical catalytic reduction of metal ions with dimethylamine borane are studied. The coatings were oxidized at 600DGC and an air pressure of 2 x 10(4) Pa. The difference in the growth morphology of the oxide layers on freshly deposited coatings and those preliminarily heated in a vacuum is revealed. The oxide films are composed of the MoO2, Mo2C, as well as amorphous and nanocrystalline NiO, phases. Electron Auger spectroscopy has shown that boron in the form of B(OH)3 is present in segregations along spheroid boundaries. Upon the oxidation of freshly deposited coatings, pits are formed as a result of the "explosive" removal of water vapors from the coating.