This article presents both theoretical and experimental approaches to the development of biocompatible coatings based on hydroxyapatite modified with titanium dioxide for orthopedic implants made from Ti 13Nb-13Zr titanium alloy. The primary objective was to enhance the adhesion, mechanical strength and antibacterial properties of the coatings by employing a combined technique: micro-arc oxidation followed by gas-thermal spraying. The influence of electrolyte composition and micro-arc oxidation parameters on the coating’s morphology, surface roughness and adhesion strength were systematically investigated. The highest values of hardness and adhesion were achieved using electrolyte containing Na₂SiO₃, NaOH and Na₂S₂O₃ in conjunction with detonation sputtering method. Morphological and elemental analyses confirmed the density, uniform elemental distribution and minimal porosity of these coatings. Mechanical stability was verified through Rockwell B scale and Martens tests. The proposed dual-step surface treat ment strategy offers a promising route for tailoring implant surfaces with multifunctional properties. The obtained results demonstrate that the proposed method can significantly improve the durability and perfor mance of orthopedic implants by producing biocompatible, corrosion-resistant, and mechanically robust coatings. Key words: Biocompatible coatings, micro-arc oxidation, surface modification, mechanical properties, surface roughness, coating adhesion.

TiO_xN_y coatings are known for their good biocompatibility and corrosion resistance and have been previously explored for biomedical applications, including cardiovascular stents. In this work, emphasis is placed on a systematic investigation of the effect of substrate bias voltage on the structural, morphological, and mechanical properties of TiO_xN_y films deposited by reactive magnetron sputtering. TiO_xN_y coatings were deposited on 316L stainless steel substrates using a pure titanium target (99.99%) in an Ar–N₂–O₂ gas mixture at various substrate bias voltages (0 to −150 V). The influence of substrate bias on the deposition rate, structure, and mechanical properties of the films was investigated. X-ray diffraction (XRD) analysis revealed the sequential phase evolution from cubic TiN to oxynitride TiON and further to TiO₂ (anatase/rutile) with increasing negative substrate bias, indicating that ion bombardment energy plays a decisive role in determining the crystallinity and phase composition of the coatings. The coating deposited at −50 V exhibited the highest hardness (~430 HV) and good adhesion strength (critical load 20–25 N). Contact angle measurements confirmed the hydrophilic behavior of the coatings, which is favorable for biomedical applications.

This study investigates the influence of multilayer architecture on the mechanical, corrosion, and tribological properties of Ti/TiN coatings deposited on biomedical Ti-6Al-4V alloy. Nine multilayer configurations were prepared by DC/RF magnetron sputtering using metallic Ti and ceramic TiN targets, with a fixed TiN/Ti ratio of 3:1 and varying total numbers of layers (3, 5, and 7) and deposition times (30, 60, and 120 min). A strict application of the 10% indentation depth rule was implemented to eliminate substrate effects, which revealed significantly higher intrinsic hardness values (540–740 HV) and indentation moduli (124–143 GPa) compared to the substrate (353 HV; 114 GPa). In contrast, conventional higher-load testing underestimated coating performance due to substrate dominance. Among the investigated architectures, the Ti/TiN-7 configuration exhibited the best balance of properties, combining high hardness (~690 HV), modulus (~137 GPa), improved corrosion resistance (Ecorr up to −0.13 V, Icorr reduced by an order of magnitude), and stable abrasive wear behavior. These findings demonstrate that both bilayer number and deposition time critically determine the mechanical and functional response of Ti/TiN multilayers. The results provide practical guidelines for the reliable characterization and design of multilayer coatings for biomedical and aerospace applications.

This study investigates the effect of the gas mixture composition ratio (Ar:N₂:O₂) during magnetron sputtering on the morphology, phase composition, and visual characteristics of TiN_xO_y thin films. Five different modes were used with a variable N₂:O₂ ratio ranging from 0.5 to 3. The resulting coatings exhibited noticeable differences in color—from golden to dark blue—which correlates with changes in chemical composition and phase state. The morphology of the films, examined by scanning electron microscopy (SEM), varied from a dense to a columnar structure. These results demonstrate that the properties of TiON coatings can be controlled by adjusting the N₂:O₂ ratio: nitrogen-rich conditions promote denser coatings with higher hardness and improved wear resistance, whereas a balanced N₂:O₂ ratio enhances coating adhesion to the substrate.

"The article discusses the effect of microarc oxidation (MDO) modes on the structural and phase state, mechanical, physical and functional characteristics of oxide coatings. Microarc oxidation (MDO) is a promising method for modifying the surface of metals, allowing the formation of durable oxide coatings with improved performance characteristics. This article examines the effect of the MDO modes, namely direct (direct) and alternating (pulsating or bipolar) currents, on the morphology, structural and phase state, mechanical and tribological properties of oxide layers. A comparative analysis of the characteristics of coatings obtained under various processing modes has been carried out, and their advantages and disadvantages have been identified. Experimental data show that the use of alternating current contributes to the formation of dense, homogeneous, wear-resistant coatings with low porosity and high adhesion to the substrate. At the same time, coatings obtained using direct current have a pronounced porous structure, which improves their anti-corrosion properties. The results obtained make it possible to better understand the mechanisms of formation of oxide layers and optimize the modes of microarc oxidation to obtain coatings with specified properties. The presented data can be useful for the development of new materials with improved functional characteristics in various industries. Keywords: microarc oxidation, direct current, alternating current, pulse mode, bipolar mode, oxide coatings, structural-phase state, microhardness."

This study investigates the formation, structure, phase composition, and performance of oxide–phosphate coatings produced by micro-arc oxidation (MAO) on coarse-grained and ultrafine-grained Ti13Nb13Zr alloy substrates. The effects of MAO treatment conditions and substrate structural state on coating morphology, thickness, elemental and phase composition, tribological behaviour, and microhardness were evaluated. All investigated coatings exhibited a similar crystalline phase composition dominated by α-Ti and TiO₂ in the anatase and rutile forms, while the relative intensities of the oxide reflections varied with processing conditions. The tribological response depended on both the MAO mode and substrate state: the lowest mean friction coefficient was obtained for the ultrafine-grained substrate in Mode 1 (μ = 0.149), whereas the highest value was observed for the coarse-grained substrate in Mode 3 (μ = 0.723). The highest microhardness in the reported dataset, 700 HV0.1, was obtained on the ultrafine-grained substrate in Mode 3 using the electrolyte containing 1.0 g/L TiO₂. SEM/EDS observations further showed that the substrate’s structural state influenced the uniformity of oxide-layer development and elemental distribution. These results demonstrate that both the electrical treatment mode and the initial microstructural state of Ti13Nb13Zr affect the characteristics of MAO-derived oxide–phosphate coatings.