Search Results (992)

AISI 1045 steel often undergoes premature failure under combined corrosive-wear conditions due to its insufficient surface durability. To address this, a hot-dip aluminum (HDA) coating was deposited on the steel substrate. The microstructure, corrosion behavior, and tribological properties of the coating were systematically characterized using scanning electron microscopy (SEM), electrochemical techniques, and tribometry. The results reveal that the coating exhibits a continuous triple-layer structure, consisting of the steel substrate, an intermediate Fe-Al intermetallic compound layer, and an outer aluminum-rich layer. In a 3.5 wt.% NaCl solution, the coating formed a protective Al₂O₃ film, demonstrating clear passivation behavior. It significantly enhanced the substrate’s performance, achieving an approximately 90% reduction in wear rate and a substantial increase in charge transfer resistance. The coated sample showed a lower friction coefficient (0.24) compared to the bare substrate (0.34). Herein, this work demonstrates that a straightforward and industrially viable hot-dip aluminizing process can effectively improve the corrosion and wear resistance of medium-carbon steel. The findings provide a practical surface-hardening strategy for such steels operating in aggressive environments. Full article

In accelerated bridge construction, precast concrete girders are connected to cast-in-place concrete slab using shear transfer reinforcement across the interface plane to ensure the composite action. The steel transverse reinforcement is prone to severe corrosion due to the extensive use of de-icing salts and severe environmental conditions. As glass fiber-reinforced polymer (GFRP) reinforcement has shown to be an effective alternative to conventional steel rebars as flexural and shear reinforcement, the present research work is exploring the performance of GFRP reinforcements as shear transfer reinforcement between precast and cast-in-place concretes. Experimental testing was carried out on forty large-scale push-off specimens. Each specimen consists of two L-shaped concrete blocks cast at different times, cold joints, where GFRP reinforcement was used as shear friction reinforcement across the interface with no special treatment applied to the concrete surface at the interface. The investigated parameters included the GFRP reinforcement shape (stirrups and headed bars), reinforcement ratio, axial stiffness, and the concrete compressive strength. The relative slip, reinforcement strain, ultimate strength, and failure modes were reported. The test results showed the effectiveness and competitive shear transfer performance of GFRP compared to steel rebars. A shear friction model for predicting the shear capacity of as-cast, cold concrete joints reinforced by GFRP reinforcement is introduced. Full article

This study investigates the tribological behavior of selective laser-sintered (SLS) sliding bearings under dry-sliding operating conditions. These polyamide-12 bearings reinforced with glass beads (PA 3200 GF) were tested against a stainless-steel sleeve in three different pressure–velocity (PV) regimes that represent real operating conditions. The coefficient of friction (COF) and contact temperatures were monitored throughout the experiment, while the specific wear rate was quantified based on mass loss measurements. The evolution of surface topography was analyzed using roughness parameters of the Abbott-Firestone family. Scanning electron microscopy (SEM) analysis was performed to identify the dominant wear mechanism. The results show a pronounced running-in phase, after which a stable thermomechanical equilibrium occurs in all regimes. Heavy-loaded regimes increase temperature but accelerate surface adaptation and lower stable coefficients of friction. Lower load regimes have the lowest thermal load but higher friction due to lower real contact. The medium PV regime has a low COF and moderate temperature rise, while peak and core roughness metrics increase more significantly. These results provide an experimentally based insight into the influence of the load regime on the tribological behavior and topography of the SLS-made polymer sliding bearings, thus contributing to a deeper understanding of their operation in real dry-sliding conditions. Full article

This study investigates the structural formation and performance characteristics of coatings produced by electric arc spraying using 20Kh13 steel wire on a 45 steel substrate with an adhesive interlayer made of 30KhGSA steel. Particular attention is paid to the effect of spraying air pressure (0.4–0.6 MPa) on the morphology, phase composition, microhardness, elastic modulus, and tribological properties of the resulting coatings. Microstructural and X-ray phase analyses revealed that increasing air pressure leads to higher coating density, reduced porosity (~2–3%), and increased content of the Fe₃O₄ oxide phase. Nanoindentation tests showed that the highest microhardness (up to 270 HV) and elastic modulus values were observed at 0.4 MPa, while the greatest structural integrity and stable frictional behavior were achieved at 0.6 MPa. Under both dry and lubricated conditions, the coatings exhibited stable performance and a low coefficient of friction (0.10–0.12 in oil), confirming the potential of the developed technology for the restoration and strengthening of component surfaces operating under combined loading and aggressive environmental conditions. Full article

The lubrication properties of gallium-matrix liquid metal (GLM) are intimately connected to the tribofilms formed through frictional processes. Physico-chemical properties of the tribofilms depend on the interfacial interactions between GLM and the surfaces of frictional pairs. Therefore, it is significant to reveal the process of interfacial interactions. In this study, considering that Ga and In atoms are the main components of GLM lubricant, the adsorption processes of Ga and In atoms on Fe (111) and Cu (111) surfaces are, respectively, investigated at the atomic level by the density functional theory (DFT) method to have an insight into the lubrication behaviors of GLM for bearing steel and albronze metals. It is found that the adsorptions of Ga atom on both Fe (111) and Cu (111) surfaces are stronger than that of In atom, and thus forming Fe-Ga bond and Cu-Ga bond. Furthermore, interfacial interactional experiments and tribological experiments are conducted to verify the results of first-principles calculations. Tribological experiments demonstrate that with FeGa₃ film on the bearing steel surface, the friction coefficient and wear rate can be reduced by 30% and 82%, while with CuGa₂ film on the albronze surface, the friction coefficient and wear rate can be reduced by 27% and 94%. Full article

Cr8 steel should be Steel containing ~8 wt.% of chromium is widely used in demanding die applications due to its excellent wear resistance; however, conventional shot peening, while enhancing strength, inevitably increases surface roughness, thereby compromising overall performance. To address this limitation, this study systematically investigates the influence of ultrasonic surface rolling (USR) step size—comparing 0.06 mm and 0.12 mm—on mitigating surface degradation and improving surface integrity. Friction wear and electrochemical corrosion tests demonstrate that USR effectively reduces surface roughness and enhances microhardness. The 0.06 mm step size achieves superior results, yielding the lowest surface roughness (0.8317 μm), highest microhardness (647.47 HV), lowest friction coefficient (0.655), and optimal corrosion resistance (minimum corrosion rate reduction: 3.472 µA·cm⁻², corresponding to an inhibition efficiency of 37.05%). These performance improvements are attributed to the synergistic effects of surface smoothing and work hardening, resulting from more uniform processing achieved under a smaller step size. Consequently, a 0.06 mm step size is determined to be optimal, establishing the integrated shot peening–USR process as a highly effective strategy for enhancing surface properties and extending the service life of critical Cr8 steel components in industrial applications. Full article

This study investigates the influence of manufacturing technology on the structural, mechanical, and antifriction properties of a new self-lubricating composite based on ShKh15 bearing-steel grinding waste to which a CaF₂ solid lubricant was added. The developed process involves regenerating grinding waste, mixing with CaF₂ powder, pressing, and sintering. This process ensures the formation of a micro-heterogeneous structure consisting of a metallic matrix with uniformly distributed CaF₂ particles. The strengthening phases and their distribution determine the composite’s tribological behavior under operating conditions of 100–200 rpm and 1.0 MPa in air. Compared to conventional cast bronze, the material exhibits superior wear resistance and a lower friction coefficient. During friction, self-renewing antifriction films form on the contact surfaces due to chemical interactions between metallic elements, oxygen, and the solid lubricant, providing a continuous self-lubricating effect. The results demonstrate that adjusting the initial alloyed waste powders and the CaF₂ content makes it possible to control the structure and performance of the composite. This research highlights the potential of using industrial grinding waste to produce efficient antifriction materials while reducing environmental impact. Full article

The continuous advancement of modern weaponry has intensified the pursuit of next-generation ballistic protection systems that integrate lightweight architectures, superior flexibility, and high energy absorption efficiency. This review provides a technological overview of current trends in the design, processing, and performance optimization of metallic, ceramic, polymeric, and composite materials for ballistic applications. Particular emphasis is placed on the role of advanced surface coatings and nanostructured interfaces as enabling technologies for improved impact resistance and multifunctionality. Conventional materials such as high-strength steels, alumina, silicon carbide, boron carbide, Kevlar^®, and ultra-high-molecular-weight polyethylene (UHMWPE) continue to dominate the field due to their outstanding mechanical properties; however, their intrinsic limitations have prompted a transition toward nanotechnology-assisted solutions. Functional coatings incorporating nanosilica, graphene and graphene oxide, carbon nanotubes (CNTs), and zinc oxide nanowires (ZnO NWs) have demonstrated significant enhancement in interfacial adhesion, inter-yarn friction, and energy dissipation. Moreover, multifunctional coatings such as CNT- and laser-induced graphene (LIG)-based layers integrate sensing capability, electromagnetic interference (EMI) shielding, and thermal stability, supporting the development of smart and adaptive protection platforms. By combining experimental evidence with computational modeling and materials informatics, this review highlights the technological impact of coating-assisted strategies in the evolution of lightweight, high-performance, and multifunctional ballistic armor systems for defense and civil protection. Full article

Water is attractive as a base fluid due to its availability and environmental friendliness. To enhance its lubricity, environmentally friendly additives must be applied. This study combined protic ionic liquid and several nanoparticles to form hybrid additives for an oil-in-water lubricant. The performance of these additives was evaluated using wettability, tribo-testing, and worn-surface analysis. The tribo-test employed a ball-on-plate reciprocating tribometer that used bearing steel/bearing steel and WC/bearing steel friction pairs. The results were compared with those obtained using two commercial additives. It was found that the investigated additives are promising candidates for water-based lubricants, as they exhibit comparable wettability. Moreover, they outperform the reference samples in terms of lubricity. According to the results, the suggested lubrication mechanism includes enhanced wettability, composite tribo-film formation, surface polishing, and mending. Full article

The pitting corrosion resistance and the tribological behaviour of a ferritic stainless steel with high Mo content (AISI 436) and a commonly employed austenitic stainless steel (AISI 304) are compared. Special attention was paid to the role of Mo in improving corrosion resistance of ferritic stainless steels. Since the surface condition is an important parameter related to the onset of pitting corrosion in the presence of chlorides, three different surface finishes were tested for both steels. Two commercial finishing grades and laboratory polishing down to 1 µm were compared. Moreover, the influence of surface condition on the tribological properties for both steels was also evaluated. The study demonstrates that surface finishing plays a decisive role in both the electrochemical and mechanical response of stainless steels. A comprehensive microstructural and tribological analysis reveals not only how commercial finishing treatments modify passive film behaviour, but also how they affect friction stability and wear mechanisms. Special emphasis is placed on the synergistic effect between molybdenum content, passive film integrity and manufacturing processes. The obtained results provide valuable insight for industrial applications where durability against chloride exposure and abrasion is critical. Full article

This study investigated the tribological and mechanical properties of chromium nitride (CrN and CrN/DLC) coatings applied to 316L steel in an artificial blood environment. The wettability of the tested surfaces was determined and the hardness was also tested using the instrumental indentation. Friction-wear tests were performed using a TRB³ tribometer in a rotating ball-on-disc configuration. The tests were performed under dry friction conditions and with lubrication using artificial blood at pH 7.45 (neutral environment) and pH 7.15 (acidified environment). Wear of the friction pairs was examined using an interferometric-confocal microscope. Artificial blood was chosen to simulate human body fluids. The use of the CrN/DLC coating reduced the coefficient of friction by 83% for dry friction, by 62% for friction with neutral artificial blood lubrication, and by 69% for friction with acidic artificial blood lubrication, respectively. Despite the increased coefficient of friction of the CrN coating, its use also contributed to reduced material wear. Full article

Machining of medium-carbon steels, such as AISI 1050, poses a significant challenge in terms of achieving stable cutting conditions, controlled chip evacuation and high surface integrity, in particular when full-face milling is performed under elevated material removal rates. The tool surface engineering approach, particularly laser-induced micro-texturing, comprises a promising route toward modifying the tribological conditions at the tool–chip interface, thus affecting friction, heat generation, chip formation and the resultant surface finish. This study investigates the combined effects of cutting speed, axial depth of cut and tool micro-texture orientation (parallel versus orthogonal to the chip flow direction) on machining performance under wet conditions. In addition to the experimental analysis of cutting forces, chip morphology and surface roughness, this work integrates a full factorial Design of Experiments, regression modeling, and ANOVA to quantify the statistical significance of each factor and to identify dominant interactions. The regression models show strong predictive capability across all measured responses, while the ANOVA confirms the axial depth of cut and tool texture orientation as the most influential parameters. Multi-objective optimization by Pareto analysis further underlines the superiority of orthogonal micro-texturing, which consistently reduces the cutting forces and improves surface quality while promoting controlled chip segmentation. The results provide quantitative and statistically validated evidence of the enhancement of lubrication effectiveness, reduction in interface friction, and stabilization in chip formation provided by the micro-textured tools. Overall, the findings contribute to the development of data-driven machining strategies and surface-engineered cutting tools in view of improved productivity, energy efficiency and surface integrity in advanced manufacturing applications. Full article

This study investigates the lubrication properties of GCr15 steel textured surfaces under the conditions of low speed, heavy load, and boundary lubrication, with varying concentrations of Al₂O₃ particles. Through pin-on-disk tests in 46# hydraulic fluid, it was found that the texture density had little effect on the friction in the absence of abrasive particles and that the friction increases with an increasing texture density in the presence of abrasive particles. Abrasive particle concentration significantly increases the friction on smooth surfaces, while textured surfaces can retain abrasive particles and lubricants, mitigating the increase in friction. The impact of abrasive particles can wear down the texture edges and weaken its friction-reducing effect. This study reveals the interaction between abrasive particle concentration and texture density, providing a theoretical basis for designing textured surfaces suitable for abrasive-containing lubrication environments. Full article

The objective of this study is to evaluate the impact of thermal and thermochemical treatment, specifically gas nitriding, on the wear properties of AISI D2 cold work tool steel. The steel was austenitized at 1050 °C, then subjected to two annealing cycles at 560 °C for two hours each. It was then gas-nitrided for 16 and 36 h. The Vickers microhardness measurements of AISI D2 steel for the three distinct conditions, non-nitrided (NN), nitride at 16 h (N16) and nitride at 36 h (N36), are 560 HV0.1, 1050 HV0.1 and 1350 HV0.1, respectively. Wear tests were conducted utilizing a ball device, under dry friction conditions at ambient temperature, with loads of 5, 10 and 15 N, over 5000, 10,000 and 15,000 cycles at a constant sliding velocity of 30 mm/s and a sliding distance of 10 mm. Furthermore, the utilization of ANFIS modeling of experimental data facilitated the prediction of the variation in the coefficient of friction as a function of nitriding conditions and specific test parameters. The results show a significant effect of nitriding, leading to a marked reduction in the coefficient of friction. In the non-nitrided condition, the average value reaches 0.80, while extended nitriding to 36 h reduces this value to around 0.49, confirming a substantial tribological improvement. This enhancement is ascribed to the formation of hard, resilient nitride layers on the steel surface, thereby increasing wear resistance and cur-tailing in industrial applications. Full article

GCr15 bearing steel sliding friction pairs, as key components in mechanical engineering applications, often undergo severe friction and wear under starved lubrication, which restricts their service life and reliability significantly. To solve this problem, this study investigates the effect of laser surface texturing on the tribological performance of GCr15 bearing steel under starved lubrication conditions. A laser marking machine is used to fabricate pit textures on GCr15 sliding surfaces, exploring the effects of processing speed, laser power, and frequency on texture integrity. Friction and wear tests under starved lubrication conditions are conducted using a vertical universal tester, and worn surfaces are characterized using a 3D surface profiler. The results show that high-integrity flat-bottom pits form at 200 mm/s, 10 W, and 80 kHz. These textures collect debris, retain lubricant, and provide secondary lubrication. At a depth-to-diameter ratio of 0.083 and area ratio of 14.9%, the friction coefficient (0.076) and wear loss (2.27 mg) decrease by 27.6% and 63.7%, respectively, compared to those of smooth samples (0.105, 6.25 mg). This study clarifies the regulatory mechanisms and provides references for improving key components’ lifespan and reliability. Full article