Wear Resistance of Plasma Electrolytic Oxidation Coatings on Ti-6Al-4V Eli Alloy Processed by Additive Manufacturing

Abstract

The additive manufacturing (AM) technique can produce Ti-6Al-4V ELI (extra low interstitial) alloy for personalized biomedical devices. However, the Ti-6Al-4V ELI alloy presents poor tribological behavior. Regarding this, coatings are a feasible approach to improve the wear resistance of this alloy. In the literature, the tribological behavior of TiO2 coatings incorporated with Ca and P formed by one-step plasma electrolytic oxidation (PEO) on Ti-6Al-4V ELI alloy processed by AM has not been investigated. Thus, in the present work, it was studied the influence of Ti-6Al-4V ELI alloy processed by AM on the wear resistance and morphologic of the coating obtained by PEO (plasma electrolytic oxidation). In this way, three different voltages (200, 250, and 300 V) were employed for the PEO process and the voltage effect on the properties of the coatings. The coatings were characterized by contact profilometry, scanning electron microscopy, energy-dispersive spectroscopy, the sessile drop method, grazing-incidence X-ray diffraction, and wear tests, on a ball-on-plate tribometer. The increase in applied voltage promoted an increase in roughness, pore area, and a decrease in the pore population of the coatings. In addition, the coatings, mainly composed of anatase and rutile, showed good adhesion to the metallic substrate, and the presence of bioactive elements Ca and P were detected. The thickness of the coatings obtained by PEO increases drastically for voltages higher than 250 V (from 4.50 ± 0.33 to 23.83 ± 1.5 µm). However, coatings obtained with lower voltages presented thin and dense layers, which promoted a superior wear resistance (increase in wear rate from 1.99 × 10−6 to 2.60 × 10−5 mm3/s). Finally, compared to the uncoated substrate, the PEO coatings increased the wear resistance of the titanium alloy obtained by AM, also showing a superior wear resistance compared to the commercial Ti-6Al-4V alloy previously evaluated, being such a positive and promising behavior for application in the area of metallic implants.

Surface Properties and Tribological Behavior of Additively Manufactured Components: A Systematic Review

“…The coatings were able to exhibit high hardness and density, as well as high wear resistance. Santos et al [143] investigated a possible coating via the plasma electrolytic oxidation of Ti6Al4V for biomedical application and demonstrated improved wear resistance compared with the untreated samples. The post-treatment of Al-Si alloy via heat treatment and electric discharge alloying (EDA) was investigated in [144].…”

The Study on Corrosion Resistance of Ti-6Al-4V ELI Alloy with Varying Surface Roughness in Hydrofluoric Acid Solution

“…The aforementioned characteristics render titanium alloy highly promising in the domains of aerospace engineering, marine engineering, and biomedical engineering [6][7][8][9]. Furthermore, the utilization of titanium alloys as raw materials for additive manufacturing is highly commendable [10][11][12][13][14]. In the extensive application scenarios of titanium alloy, the service performance of titanium alloy is contingent upon its corrosion resistance [15], a critical property that has attracted considerable interest from researchers and engineers.…”

“…For example, titanium alloys used as dental implants in the oral cavity are frequently exposed to fluoride ions from toothpaste Metals 2024, 14, 364 2 of 13 or tap water. It has been demonstrated that implants can often benefit from optimal surface roughness and microstructural features [14,20,21].…”

Calcium Phosphate Coatings Deposited on 3D-Printed Ti–6Al–4V Alloy by Plasma Electrolytic Oxidation

“…Anatase has been associated with superior cytocompatible behavior in terms of osteoblast proliferation and adhesion [16,17]. The rutile phase exhibits greater hardness compared to the anatase phase, along with reduced wear and friction properties [18][19][20]. By selecting the most optimal modes and combining components such as anatase and rutile, it is possible to improve the mechanical and tribological properties of the PEO coating.…”