On the Effect of an Electrolyte and Impregnating Solution on Microcrystal Growth on the Surface of W-Containing PEO Coatings on Titanium at Oxidative Annealing

It has been confirmed in the present work that the components of an electrolyte and impregnating solution accumulated in pores can serve as a material for the microcrystal formation on the surface of oxide layers at high-temperature oxidative annealing. WO 3 microcrystals were formed in the pores and along the pore perimeter of coatings formed by the method of plasma-electrolytic oxidation (PEO) in aqueous solutions with Na 2 WO 4 . Hemispheres containing NiWO 4 nanogranules occluded the coating pores after their additional impregnation with an aqueous solution Ni(NO 3 ) 2 and annealing. The pore content has been analyzed, and possible mechanisms for its transformation into microcrystals and hemispheres have been considered. The obtained results were important for determination of the methods of targeted change in the composition and architecture of the complex oxide coatings' surface and, consequently, for controlling their functional properties.