Investigation of Biocompatible PEO Coating Growth on cp-Ti with In Situ Spectroscopic Methods

Abstract

The problem of the optimization of properties for biocompatible coatings as functional materials requires in-depth understanding of the coating formation processes; this allows for precise manufacturing of new generation implantable devices. Plasma electrolytic oxidation (PEO) opens the possibility for the design of biomimetic surfaces for better biocompatibility of titanium materials. The pulsed bipolar PEO process of cp-Ti under voltage control was investigated using joint analysis of the surface characterization and by in situ methods of impedance spectroscopy and optical emission spectroscopy. Scanning electron microscopy, X-ray diffractometry, coating thickness, and roughness measurements were used to characterize the surface morphology evolution during the treatment for 5 min. In situ impedance spectroscopy facilitated the evaluation of the PEO process frequency response and proposed the underlying equivalent circuit where parameters were correlated with the coating layer properties. In situ optical emission spectroscopy helped to analyze the spectral line evolutions for the substrate material and electrolyte species and to justify a method to estimate the coating thickness via the relation of the spectral line intensities. As a result, the optimal treatment time was established as 2 min; this provides a 9–11 µm thick PEO coating with Ra 1 µm, 3–5% porosity, and containing 75% of anatase. The methods for in-situ spectral diagnostics of the coating thickness and roughness were justified so that the treatment time can be corrected online when the coating achieves the required properties.

Hydroxyapatite Coating on Ti-6Al-7Nb Alloy by Plasma Electrolytic Oxidation in Salt-Based Electrolyte

“…In recent years, the plasma electrolytic oxidation (PEO) method [ 30 ] has been used as an alternative approach to the production of ceramic coatings with high adhesion and anticorrosion properties [ 31 ]. The PEO method is based on anodic or alternating current polarization of the processed material in aqueous electrolytes at a high voltage, producing micro arc discharges that flow on the electrode surface [ 32 , 33 ].…”

Impact of Sandblasting and Plasma Electrolytic Oxidation on Surface Quality of Dental Implants

“…The results of preliminary experiments to develop the method demonstrated that in order to obtain a uniform PEO coating on implants, surface pretreatment by sandblasting is required to create favorable conditions for microdischarge ignition. The formed coating consists of TiO 2 anatase (60-70%) and TiO 2 rutile (40-30%) [12].…”

“…Microcontroller system maintained the electrolyte temperature at 20±1°C. The PEO was performed with a pulsed bipolar mode, subject to stabilization of the pulse voltage [12], for 2 min. The treatment was carried out in an alkaline phosphate electrolyte with a conductivity of 15.3 mS/cm.…”

“…Along with sandblasting, plasma electrolytic oxidation (PEO) of the implant surface is a topical method to create an oxide coating with improved biocompatibility [11]. With this method applied, the value of surface roughness R a is maintained at the level of 1.0-1.5 μm, and the coating with a thickness of 10-20 μm has a porous structure and provides good corrosion resistance [12]. According to recent studies, PEO-coated dental implants are characterized by improved biocompatibility [13].…”

All-atom molecular dynamics simulations of polymer and polyelectrolyte brushes

“…Since there is no net charge on the polymer chains, the chemical functional groups of the polymer chains play a vital role in determining the properties exhibited by such brushes. Some widely used uncharged polymer brushes are poly( N -isopropyl acrylamide) or PNIPAM, which is known for their thermos-responsive properties; 116 polyethylene oxide or PEO, known for their biocompatibility properties 117 as well as their ion-conducting properties (leveraged in fabricating solid polymer electrolytes 118 ); polypropylene oxide (PPO); 119 polydimethylsiloxane (PDMS); 120 etc. The chemical structures for the monomers of some of these different uncharged polymer chains have been provided in Fig.…”