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.

This paper presents a study of the structural and mechanical degradation of tungsten under steady-state mixed hydrogen–helium plasma (He/H₂). The experiments were carried out on the KAZ-PSI linear plasma simulator at a surface temperature of 1100 °C, while the helium fraction in the mixture was varied from 5% to 50%. Changes in surface morphology, roughness, phase composition, micromechanical response, and gas retention were analyzed using profilometry, scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD), nanoindentation, and thermal desorption spectroscopy (TDS). The results show that increasing the helium fraction promotes the formation of a porous, defect-rich near-surface layer and modifies the gas-trapping behavior of tungsten. The surface roughness increases moderately from 0.031 μm for the initial polished state to 0.065 μm after exposure to a 50% He/50% H₂ plasma. EDS and XRD confirm that the observed degradation is not associated with detectable oxidation, carburization, or the formation of secondary crystalline phases. The TDS results indicate that helium-related vacancy complexes and gas-filled pores act as deep trapping sites for hydrogen. Therefore, the helium-modified near-surface layer should be considered as a trapping barrier that localizes hydrogen in the radiation-damaged layer rather than as a quantitatively proven diffusion barrier blocking hydrogen penetration into the bulk.

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.

Tungsten plasma-facing components in fusion devices may experience sequential exposure to helium and hydrogen, making irradiation history an important factor in their subsequent structural and hydrogen-release behavior. This study investigated polycrystalline tungsten exposed to He-only, H₂-only, and sequential He → H₂ plasmas at 700, 900, 1100, and 1300 °C. Surface and cross-sectional scanning electron microscopy, X-ray diffraction, instrumented indentation, and thermal desorption spectroscopy (TDS) were used to characterize the resulting changes. SEM observations showed that the largest differences among the H₂-only, He-only, and sequential He → H₂ exposure conditions occurred at 1100 °C, whereas predominantly grain-scale surface morphology was observed for all three conditions at 1300 °C. The bcc-W structure was retained under all investigated conditions, with no detectable secondary crystalline phases. The apparent coherent diffraction domain size, estimated from the W(110) reflection using the Scherrer equation, increased monotonically with irradiation temperature, from approximately 48–55 nm at 700 °C to approximately 126 nm at 1300 °C. At 1100 °C, the H₂-only specimen exhibited a larger apparent coherent diffraction domain size than the He-containing specimens. The nanomechanical response also depended on temperature and exposure history. TDS revealed distinct high-temperature hydrogen-desorption behavior for the sequential He → H₂ specimens, particularly at 1100 and 1300 °C. Overall, the results indicate that the tungsten response under the present sequential protocol depends on both temperature and exposure history, and that structural convergence at elevated temperature does not necessarily correspond to equivalent hydrogen-release behavior.

"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."