Electrochemical Alloying of the Titanium Alloy Surface With Palladium

To improve the corrosion resistance of titanium alloys, various methods of surface treatment are used. This paper presents a method of electrochemical surface alloying with a noble metal (in particular, palladium) of a titanium alloy and the choice of a mode of deposition of local electrochemical nanoscale coatings to improve corrosion resistance. The mode of electrode polarization of titanium alloy VT1-0 has a significant effect on the number of nuclei and the thickness of the layer of separated elemental palladium on the surface. The methods of scanning electron microscopy and Auger-electron spectroscopy were used to study the morphology, elemental composition of the surface and near-surface layers, and the distribution of elements by the layer thickness. The size of elemental palladium nucleation on the surface of titanium alloy sample VT1-0, aged in a solution containing 1% Pd(II) without polarization, is approximately 3 nm. The thickness of the elemental palladium layer on the titanium alloy sample polarized with a direct current density of 2 μA/cm2 in the solution under study reaches 6 nm. The modified sample obtained by polarization of a titanium alloy in a solution containing 1% Pd(II) with an alternating current of infra-low frequency has on its surface a layer of elemental palladium 40-600 nm thick, unevenly distributed on the surface. The elemental composition of the surface of the modified titanium alloy samples was determined by Auger spectral analysis: Pd, O, Ti in the order of decreasing elemental content by the thickness of the surface layer. Samples of titanium alloy modified under the influence of alternating and direct current in the solution under study were subjected to corrosion tests in the medium of hydrochloric acid with a concentration of 5.0 M. The tests showed that the sample with the surface alloyed with palladium using alternating current is the most corrosion-resistant.