K₂[TiO(C₂O₄)₂] is decomposed by micro-arcs on the anode producing TiO₂ while hydroxyapatite particles are incorporated into TiO₂ coating during electrophoretic deposition.

Composite coatings containing aluminum oxide and polyethylene are deposited using microplasma electrochemical anodic treatment of the iron surface in an aluminate bath at a voltage of 260–360 V. Using scanning electron microscopy, microprobe analysis, Fourier transform infrared spectroscopy, and electrochemical polarization measurements, the composition, structure, and corrosion characteristics of the coatings are determined. Adding 0.5–1.0 wt % polyethylene dispersion to the electrolyte is shown to substantially facilitate the origination of microplasma conditions, prevent the strong warming of electrolyte during anodizing, and obtain coatings with substantially higher corrosion resistance compared to those produced in an aluminate bath containing no polymer dispersion.

The addition of Cr nanoparticles to a plasma electrolytic oxidation (PEO) electrolyte offers the possibility of producing layers with a broader range of coating compositions and improved properties. In this study, the effects of nanoparticles and various voltages on coating formation, microscopic morphology, and phase composition were investigated with in situ incorporation of Cr nanoparticles into PEO-coated Mg alloy. The results show that the corrosion performance of the coating was significantly improved when the final voltage was set to 460 V and the concentration of Cr nanoparticles was 1 g/L. Compared to the particle-free coating, the corrosion current density of the coating with the addition of 1 g/L Cr nanoparticles was reduced by two orders of magnitude. The impedance at the low frequency (0.01 Hz) increased by more than one order of magnitude after one hour of immersion, indicating a considerable improvement in corrosion resistance. Due to the high temperature during the coating-formation process, the Cr nanoparticles were oxidized, resulting in the formation of Cr₂O₃. The existence of Cr₂O₃ slightly increased the growth rate of the coating and sealed the open pores of the coating.

Thick ZnO/ZnAl₂O₄ coatings were synthesized on zinc alloy Z1 substrates through plasma electrolytic oxidation (PEO) for different anodization times. The prepared coatings were characterized by scanning SEM, XRD, diffuse reflectance and photoluminescence spectroscopy in order to establish the relationship between their structural and optical properties and PEO processing parameters. Under different PEO processing conditions (anodization time—1–10 min and applied voltage—370 and 450 V) ceramic coatings with a mean thickness of 2–12 μm were prepared. XRD analysis explored the coating structure composed of zinc oxide (wurtzite) and zinc aluminate spinel. The content of ZnAl₂O₄ in the coatings grows with increasing the applied voltage and anodization time. Photoluminescence (PL) measurements showed that the PEO coatings have several bands in the visible and near-infrared regions associated with their composite structure. The PL spectra significantly depend on the PEO processing parameters due to varying ZnO and ZnAl₂O₄ content in the coatings. The insight in the relationship between the ZnAl₂O₄ structure and the photoluminescent properties of ZnO/ZnAl₂O₄ coatings has been provided using the combination of XRD and luminescence spectroscopy.