Kinetic features of wear-resistant coating growth by plasma electrolytic oxidation

Abstract

The kinetic features of coating growth on titanium alloy Ti–6A1–4V by plasma electrolytic oxidation (PEO) are investigated. It was observed that the coating growth rate decreases significantly with the increasing of the PEO time treatment. At the same time, large longitudinal pores (cracks) were formed; thus, the major part of the coating is separated from the substrate. Coating growth is realized by the two mechanisms: (a) migration-diffusional and (b) thermochemical treatment of the deposited aluminum hydroxide (electrolysis) and oxidation of the substrate at the bottom of the coating pores. It presumably occurs due to the saturation of the electrolyte in the pores with titanium hydroxide and the relatively low intensity of the microdischarges, which is insufficient to eject the substance from the channels for ‘pancake’ formation. This increases the amount of the aluminum titanate (TiAl2O5) in the coating. The latter presumably forms due to a eutectic reaction in the coating or due to the exothermic reactions of titanium dioxide formation. The TiAl2O5-based coating containing at least 10% aluminum oxide α-Al2O3 (more than 20% in the outer layer) and 11% titanium dioxide (TiO2) increases the wear resistance of the titanium alloy at least six times.

Experimental investigation of the adhesion force of single and double‐layer coatings on MEMS surfaces

“…TiO 2 thin films suitable for applications of MEMS containing stress are micromachined by dry etching and wettability conversion. These investigations indicate that smooth TiO 2 ‐based MEMS devices with mechanical properties can be realized …”

Editorial

“…A wear-resistant coating was investigated by Tailor et al 5 The authors successfully used plasma electrolytic oxidation, an electrochemical surface treatment process for producing an oxide coating composed of TiAl 2 O 5 and a-Al 2 O 3 on titanium alloy Ti-6Al-4V. They report a decrease in the coating growth rate with processing time, with formation of porosity.…”

Nanotubular Oxide Layer Formed on Helix Surfaces of Dental Screw Implants

“…Coatings 2021, 11, 115 2 of 10 Among various surface treatments, artificial oxidation seems particularly plausible for titanium dental implants resulting in high corrosion resistance and biocompatibility [21]. The oxidation required for dental implants is currently mostly applied by micro-arc oxidation (MAO) [22,23] and electrochemical oxidation [24]. Gaseous oxidation has also been proposed [25].…”