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Fretting wear is one of the main degradation mechanisms produced in steel wire and it is widely used for the lifting and handling of equipments. The main objective of the present work is to analyse the mechanical properties of the fretting and non-fretting wire. Statics tensile tests were performed on non-fretting wire and pre-damaged artificially fretting wire subsequently, after that tensile stress (σT), tensile strain (εT), and breaking load (BL) were measured for both wires and their basic mechanical properties were compared. For the analysis wire diameter values varies from 7 mm to 9 mm and artificially pre-damaged wire having reduced diameters varies from 5.8 mm to 8.1 mm were used. From these tests the basic mechanical properties values of maximum tensile stress, tensile strain, modulus of elasticity (E), breaking load (BL) 1610 N/mm², 12.08%, 78854.3 Mpa and 56.73 KN respectively were obtained, for pre-damaged artificially fretting wire. On the other hand, for the non-fretting wire, the values of maximum tensile stress, tensile strain, modulus of elasticity, and breaking load have been obtained as 1171.5 MPa, 16.40 %, 63289.4 MPa and 58.7 KN respectively. [ABSTRACT FROM AUTHOR]

The present research aims to investigate the combined influence of arc current and travel speed in terms of heat input during tungsten inert gas (TIG) welding and examine it through microstructural, mechanical, and wear characterizations. An automated welding setup was employed to fabricate the dissimilar AA6061-T6 and AA7075-T6 aluminum joints in a butt configuration. Macro and micrographic inspections were also conducted and investigated the changes across the weld cross-section with respect to heat input. Tensile, Charpy impact, residual stress, and wear tests were performed to examine the quality and strength of the joint. The results revealed that the joints with increased heat input displayed higher ultimate tensile strength, impact toughness, residual stress, and wear resistance. The consistent distribution of intermetallic phases and the fine equiaxed grains with minimal porosity development are probably responsible for it. However, excessive heat input caused reversion phenomena, coarser grains, and significant porosities, which reduced the tensile strength, impact toughness, and wear resistance of the joint. The welded sample S-3, having a welding current of 145 A, a travel speed of 78 mm/min, and a heat input of 1.67 kJ/mm, exhibited the highest ultimate tensile strength of 178 MPa, the largest elongation of 12.6%, the highest impact toughness of 13 J, and the lowest wear rate of 34 µm, along with a compressive residual stress of 60 MPa at the weld centre. The analysis of tensile and impact-fractured surfaces using SEM and EDS analyses validated the experimental results. [ABSTRACT FROM AUTHOR]

The development of multidrug-resistant bacterial infections seriously threatens public health. Hence, efforts are needed to develop a class of safe and effective antibacterial agents. Here, we report the synthesis of surface-modified molybdenum disulfide nanoflowers using a biogenic capping agent l-cysteine (MoS2-cys NFs). The morphological characterizations confirm the flower-like morphology with a 537 ± 12 nm size. Further, structural and surface investigations confirm the formation of the hexagonal phase of NFs and modification by l-cysteine. Also, the surface alteration of NFs by l-cysteine contributes to enhanced colloidal stability in aqueous media. The as-prepared MoS2-cys NFs exhibit excellent bactericidal activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. The scanning electron microscopy images of the bacteria confirm the membrane-directed antibacterial mechanisms, where the nanosheets in the NFs act as nanoblades and cause cell membrane damage. The antibacterial mechanisms of MoS2-cys NFs are primarily attributed to membrane damage and the generation of oxidative stresses, which destroy both bacterial strains. The generation of oxidative stress can occur through reactive oxygen species-dependent and -independent pathways validated using flow cytometry and fluorescence imaging with DCFH-DA staining and Ellman's assay, respectively. The excessive generation of ROS leads to inactivation of the bacterial antioxidant defense mechanism. The toxicity studies of the MoS2-cys NFs toward human foreskin fibroblast cell lines suggested good biocompatibility with a cell viability of nearly 90%. We report an excellent intrinsic antibacterial efficiency of MoS2-cys NFs without any external stimulus (light, H2O2, etc.), additional functionalization or complexation, doping, drug loading, etc. Our study indicates that the appropriate surface modification of the flower-like morphology of MoS2 can enhance their colloidal stability and intrinsic antibacterial potency for further applications such as antibacterial coatings, water disinfection, and wound healing. [ABSTRACT FROM AUTHOR]