EPR of transition metal ions in microplasma coatings on the surface of Ti − 0 , 3al and Ti − 6Al − 4V titanium alloys

The study focuses on the EPR examination of titanium oxidation states and doped transition metal ions in microplasma coatings on the surface of details made of Ti − 0 , 3al and Ti − 6Al − 4V titanium alloys, depending on the duration and modes of the microplasma oxidation process. No Ti3 + states are observed in the anodic mode of microplasma oxidation. When the microplasma process is conducted in the anodic-cathodic mode, paramagnetic Fe3 + and Ti3 + states are observed in the Ti − 0 , 3al alloy, and V4 + and Ti3 + states are found in the Ti − 6Al − 4V alloy. The removal of the technological layer mostly containing low-temperature titanium oxides eliminates the EPR spectra of the mentioned paramagnetic states of transition metal ions. The anodic mode of microplasma oxidation followed by the anodic-cathodic mode at the final stage does not yield paramagnetic states of transition metal ions, which is very important for many applications of microplasma oxidation of coatings because the Ti3 + state is chemically active and may affect many chemical processes occurring on the oxide layer surface. Meanwhile, the inverse sequence of the microplasma oxidation modes gives rise to paramagnetic states of transition metal ions in the technological layer.