Triboelectric Performance of Ionic Liquid, Synthetic, and Vegetable Oil-Based Polytetrafluoroethylene (PTFE) Greases

Within electrical contacts, poor electrical conductivity of lubricants can lead to triboelectric charging, causing electrostatic currents and thermal effects, which accelerate lubrication failure. This study aimed to address these challenges by producing and testing three greases with different base oils: ionic liquid ([Oley][Oleic]), synthetic oil (PAO4), and vegetable oil-based synthetic ester (trimethylolpropane oleate). Each grease was prepared with polytetrafluoroethylene powder as the thickener. The greases were tested using a custom-made tribometer, integrated with a grounded electrical current system, with friction tests conducted with up to a 2 A electrical current flow at a constant voltage supply of 4.5 V. Under triboelectric friction testing, [Oley][Oleic] grease outperformed a commercial perfluoropolyether grease by 27.7% in friction and 16.3% in wear. This grease also showed better performance than formulated lithium grease with extreme pressure additives. The study demonstrates that greases with low interfacial resistance can retain their lubrication capacity under triboelectric conditions. These results indicate that [Oley][Oleic] grease, with its ionic liquid base oil, offers a promising solution for applications involving electrical contacts. This study highlights the potential of using advanced base oils and thickeners to enhance the performance and sustainability of lubricants in demanding environment

Biocompatibility and Corrosion Resistance of Si/ZrO₂ Bioceramic Coating on AZ91D Using Electron Beam Physical Vapor Deposition (EB-PVD) for Advanced Biomedical Applications

Herein, ZrO2 and Si + ZrO2 composite coatings on AZ91D alloys are deposited at a constant voltage of 8 kV and 1 Å/s deposition rate using the electron beam physical vapor deposition (EBPVD) method. Further, the samples are examined for surface morphology, phase analysis, adhesion, corrosion, and antibacterial properties, as per ASTM standards. The adhesion strength of the composite (Si + ZrO2) coating nominally dropped (9%) compared to the ZrO2 coating even when the coating thickness increased by 18%. However, the composite (Si + ZrO2) coating improved wettability because silanol promotes hydrogen bonding with water molecules, which elevates the surface energy of the silica and increases its hydrophilic nature. Further, increased wettability and surface roughness have the potential to improve cell adhesion and proliferation. The corrosion potential (Ecorr) values of the coated samples exhibited a positive shift in the potentiodynamic polarization curve, indicating a substantial increase in their corrosion resistance in the artificial blood plasma (ABP) electrolyte. Similarly, SEM images of both coated corroded samples are less affected in the ABP solution, indicating that the coating mitigated heavy cracks and micropores, protecting them from corrosion. The Si + ZrO2 coatings exhibited exceptional performance in preventing bacterial infiltration by Staphylococcus aureus, thus inhibiting the subsequent formation of biofilms. In addition, these coatings demonstrate improved vitality among fibroblast cells, enabling better cellular spreading and proliferation

Hydroxyapatite Reinforced Magnesium Alloy Composites Using the Ultrasonic-Assisted Rheo-Squeeze Casting Technique: Microstructural and Mechanical Performance Evaluation for Bone Fixture Applications

Magnesium-based biomaterials have recently been in the research spotlight in the field of biomedical engineering owing to their properties, such as density and biocompatibility that closely align with those of human bone. However, poor strength and rapid degradation impede their application as bone support fixtures. The present research aims to tailor the properties of Mg by using a novel ultrasonic-assisted rheo-squeeze casting approach. To satisfy the demand, pure Mg (Mg), MHA (Mg/5%HA), MZHA (Mg-1%Zn/5%HA/), and MSHA (Mg-1%Sn/5%HA) were fabricated, and various mechanical tests were conducted to assess the composite’s mechanical properties, including its microhardness, tensile strength, compressive strength, flexural strength, and impact strength. The microstructural and fractured morphology of the composites was examined by scanning electron microscopy (SEM), whereas their elemental composition was analyzed by field emission scanning electron microscopy (FESEM) equipped with elemental mapping. Comparing the MZHA, MHA, and pure Mg samples, the mechanical behavior of MSHA is significantly superior. This is due to composites containing Sn that possess finer-grained materials, which act as barriers to dislocation motion while increasing the strength of the materials. From the observed results, there is a significant improvement in the microhardness of MSHA of 64.5% when compared to that of pure Mg, and 42.7% compared to MHA. Furthermore, MSHA composites possess noticeable enhancements in tensile and compression performance of 80.8% and 58.3%, respectively, and 19% and 22.4% compared to MHA. Additionally, the impact and flexural performance of MSHA composites exhibit higher performance (41% and 42%) than pure Mg and 8% and 7% against the MHA composite

Post-processing of wire-arc additive manufactured stainless steel 316 l bone staples using laser shock peening:a mechanical and antibacterial study

The paper presents the effect of post-processing with laser shock peening (LSP) on the mechanical and antibacterial properties of wire-arc additive manufactured (WAAM) SS316L bone staples. It is observed that the tensile strength and toughness of the WAAM-built SS316L bone staples improved significantly by LSP treatment, which is essential to their longevity and capacity to function under mechanical stress. The LSP-treated samples showed an enhanced presence of significant alloying elements like molybdenum, nickel, and chromium, which are essential for corrosion resistance, as well as a refined microstructure with fewer surface flaws. Furthermore, the antibacterial research showed that the LSP treatment gives the bone staples improved antibacterial qualities. A significant decrease in bacterial colonization was observed in the LSP-treated samples when compared across different periods (24, 48, and 72 h), suggesting the possibility of lower infection rates in clinical settings. SEM images displayed a reduction in biofilm formation with increasing LSP intensity, suggesting improved bacterial resistance due to surface smoothening and densification from LSP. This shows the effectiveness and significance of WAAM integrated with LSP to enhance the mechanical and antibacterial properties of SS316L bone staples, potentially leading to improved medical implants