Bone fractures and skeletal injuries resulting from trauma, accidents, or diseases remain a major global health concern, often requiring surgical intervention with orthopedic implants. Titanium-alloys, are commonly employed due to superior structural properties and excellent corrosion resistance. However, these implants lack antibacterial activity and may release toxic ions, increasing the risk of infection, inflammation, and impaired bone healing. Surface modification using bioactive coatings is a promising strategy to overcome these limitations. In this study, a green-synthesized Saraca asoca mediated zinc oxide and polyvinyl alcohol (SA-ZnO/PVA) nanocomposite coating was applied to Ti-6Al-4V substrates, followed by characterization and evaluation of their biological performance. The coated and uncoated substrates were evaluated for mechanical strength, surface topography, and in vitro biological performance using MC3T3-E1 osteoblast cells, including cell viability, migration, reactive oxygen species (ROS) production, and osteogenic differentiation. In vivo studies in a rat femur defect model assessed the potential of coating for bone regeneration, osseointegration, systemic inflammatory response, and visceral organ toxicity. The SA-ZnO/PVA coated substrates maintained mechanical integrity, supported higher osteoblast viability with lower ROS levels compared to uncoated titanium. Coated substrates also promoted faster cell migration, enhanced early osteogenic differentiation, and improved bone formation. These findings suggest that SA-ZnO/PVA coating enhances the antibacterial, cytocompatibility, and hemocompatible properties of Ti-6Al-4V alloy, promoting faster and safer bone healing. The study demonstrates that green synthesized zinc oxide nanoparticles blended PVA coatings effectively enhances the surface properties of Ti-6Al-4V, making it a suitable for orthopedic implant applications.
Friction stir welding (FSW) is an effective joining approach for dissimilar base metals, such as aluminum alloys (AA) and advanced high-strength steels. However, tool degradation during the process can compromise weld quality, shorten tool life, and increase production costs. This study evaluates the performance and durability enhancement of the tool through the FSW of AA6022-T4 and galvanized DP600 steel by applying Cr 3 C 2 -Ti-DLC thin-film coatings on H13 tool steel and WC-10% Co tools. The surface finish quality of the welds was quantitatively evaluated using a 3D white light interferometer, while real-time thermal profiles were captured using an infrared thermography camera. Tool degradation patterns and performance were assessed through optical microscopy, SEM coupled with EDS, and precise weight loss measurements. The uncoated H13 tool exhibited significant degradation, including thread flattening, micro-abrasion, and material pickup. In contrast, the uncoated WC-10% Co tool demonstrated improved wear resistance. The deposition of thin-film surface coatings significantly reduced tool degradation by 26% for H13 and 23% for WC-10% Co tools in comparison with uncoated tools. These findings demonstrate the effectiveness of thin-film surface coatings in improving tool performance and durability, particularly in dissimilar material friction stir welding.
With increasing demands for wear-resistant titanium alloy components in aerospace applications, surface engineering routes that combine ceramic reinforcement with laser-based thermal-field regulation are attracting growing attention. In this work, annular-oscillating laser cladding was employed to deposit Nano-TiN/Ti6Al4V composite coatings containing 0, 1, 6 and 12 wt.% TiN on Ti6Al4V substrates. The study focuses on how Nano-TiN addition modifies the phase constitution, microstructural evolution, microhardness and sliding wear response of the coatings. The results indicate that Nano-TiN promotes microstructural refinement and increases coating hardness, providing an important basis for improving the surface load-bearing capacity of Ti6Al4V. When the Nano-TiN addition was 1, 6 and 12 wt.%, the microhardness increased by 18.5%, 44.1% and 57.3%, respectively, relative to the TiN-free coating. However, the wear resistance showed an initial increase followed by a decline, and the coating containing 6 wt.% TiN exhibited the optimum wear resistance, with a 27.9% reduction in wear volume relative to the TiN-free coating. A suitable Nano-TiN addition improves the load-bearing capacity of the surface layer through microstructural refinement and hard-phase strengthening, whereas excessive Nano-TiN causes particle enrichment and agglomeration, promoting particle pull-out and third-body abrasive wear, and thus reduce wear resistance. These results indicate that annular-oscillating laser cladding combined with an appropriate Nano-TiN addition provides a practical route for designing wear-resistant Ti6Al4V surface coatings.
Environmental studies focused on steel surface hardening technologies, particularly laser hardening and nitriding treatments, are notably scarce. Consequently, the environmental impact of steel laser hardening and nitriding treatments requires further investigation to identify measures that can enhance the sustainability of the steel component industry. Within this framework, a Life Cycle Assessment (LCA) study was carried out to evaluate and compare the environmental aspects and potential impacts associated with steel surface hardening through laser hardening (LH), low pressure nitriding (LPN), and plasma nitriding (PN). The results for Global Warming Potential (GWP) and Cumulative Energy Demand (CED) show that, when considering the treated surface area (m 2 ), LH presents the lowest environmental impact among the three technologies for a single m 2 . Nevertheless, the break-even points were determined to be approximately 2.07 m 2 for PN and 2.55 m 2 for LPN. Although LH exhibits greater environmental impact when larger surface areas are treated, it demonstrates superior environmental performance for smaller treated areas.
