Thermally Stimulated Transformation of the Surface Nanoarchitecture of Ni-and Cu-Doped Oxide Coatings on Titanium

摘要

It has been shown that triangular nanocrystals with a thickness of ～50 nm and a height of ～ 500 nm, mainly containing copper oxides, are formed on the surface of Ni- and Cu-doped plasma electrolytic oxide (PEO) coatings on titanium during air annealing at 500-700°C. Upon the annealing at 750-850°C, rectangular nano- and micro-sized crystals presumably consisting of nickel tungstate cover the coating surface. At annealing temperatures above 850°C, the brushes of Ni_5TiO_7 whiskers having a diameter of tens to 200 nm and a length up to 10μm are formed on the surface. The thermally stimulated change in the surface nanoarchitecture and the composition of nano-formations explains the change in the catalytic activity of the formed composites in oxidation of CO into CO_2.