Investigating potential, current, and voltage in the deposition of calcium phosphate-based films using plasma electrolytic oxidation

Materials Today Communications

2025-03

Surface tension

Plasma electrolytic oxidation

Ca/P ratio

Hydroxyapatite

Techniques that promote surface coating with thin films have been explored to modify surface properties such as wear and corrosion resistance, biocompatibility, and electrical conductivity, among others. Plasma Electrolytic Oxidation (PEO) is one of these techniques that, in addition to promoting the deposition of oxide films based on the metal under treatment, has also been used for the deposition of ceramic-based materials, depending on the electrolyte used. Among these electrolytes, one in particular has been studied with some frequency, as the aim is to improve the biocompatibility of metallic materials. Films composed of calcium phosphate, commonly hydroxyapatite (Hap), show similarity to human bone, which favors cell adhesion and implant fixation. This study investigated the effect of layer growth on the current variation during the deposition treatment, with the sample at both cathodic and anodic potential. Thus, grade 2 titanium (Ti Gr2) samples were subjected to plasma electrolytic oxidation treatment, varying the deposition time to 15, 30, 60, and 90 seconds, as well as the polarization potential of the samples (cathodic and anodic). Subsequently, the surface tension of the samples, the chemical composition, and the morphology of the deposited layers were evaluated using a goniometer, XRF, and SEM, respectively. The results showed calcium deposition is more significant for samples at cathodic potential, but phosphorus deposition is indifferent to the sample's polarity. For treatment times exceeding 60 seconds, shear of the deposited layer is observed at anodic potential and densification of the layer at cathodic potential, in the latter case due to the increase in the temperature of the electrolyte solution