Tribological Properties Research Articles

Reliable and high-performance Ag-doped MoSi2 film with enhanced mechanical and tribological properties

The Mo-Ag-Si solid solution film was prepared using magnetron sputtering to enhance hardness and toughness while reducing friction and wear. Compared with the pure MoSi2 film, the Mo-Ag-Si solid solution film exhibited a 25.69% increase in hardness, a 5.17% increase in the H/E ratio, and a 33.33% boost in the H³/E² ratio. Tribological tests revealed that Ag atoms formed a self-lubricating AgMoxOy phase, reducing the friction coefficient to 0.09 and the wear rate to 3.89 × 10⁻⁷ mm³/N·m over 565m. First-principle calculations indicate that the Mo-Ag-Si solid solution film exhibited better mechanical and tribological properties than the pure MoSi2 film. These findings provide another approach for developing reliable MoSi2 films with high performance.

Application of chokeberry biochar as a modified additive to the vegetable lubricants: the tribological and rheological properties

Effect of modifying a vegetable grease with different amounts of chokeberry biocarbon on its tribological and rheological properties. The aim of the research was to investigate the effect of the incorporation of biochar derived from the pyrolysis of chokeberry biomass at 500 and 700 °C respectively, in lubricants formulated with vegetable oil, on their functional characteristics in terms of tribology and rheology. Fumed silicon dioxide was utilized as a thickening agent, ensuring the production of lubricants with a consistency class of II. The biochar was introduced into the lubricating formulations in concentrations of 1, 3, and 5%. A rapeseed-based grease with commercial activated carbon served as the reference sample. The research focused on assessing how this innovative additive influenced both the tribological and rheological behaviors of the resulting lubricants. The study evaluated the effects of chokeberry-derived biochar on the wear resistance and scuffing prevention properties of the vegetable-based greases. Additionally, the biochar’s influence on various rheological parameters such as flow curves, viscosity profiles, hysteresis loops, and viscoelastic characteristics was analyzed. Results demonstrated that the biochar additive considerably enhanced the tribological and rheological performance of the tested rapeseed-based grease.

Fabrication and tribological properties of bionic surface texture self-lubricating 60NiTi alloy via selective laser melting and infiltration

Due to its low elastic modulus, low density, non-magnetic and good lubricity, 60NiTi alloy is considered a novel fourth-generation aerospace bearing material. In this paper, 60NiTi biomimetic surface textured self-lubricating composites were fabricated by selective laser melting (SLM) and high-temperature fusion infiltration (HTFI). The effects of different slit widths (NTD), edge lengths (NTA), and soft metal Sn-Pb-Ag (SPA) infiltration on its tribological properties were studied. The results show that the NTA-SPA structural samples with medium texture density (ρ=16%) promoted the diffusion of the lubricant phase to the friction surface, resulting in a complete lubricant film. The COF stabilized at 0.2, and the wear rate decreased to 0.56×10-3 mm3/Nm, providing a more stable self-lubrication effect compared to the NTD-SPA sample.

Effects of various laser cladding materials on the tribological properties of damaged wheel treads under various temperatures and humidities

Laser cladding technology is used to repair damaged wheels and plays an important role in prolonging their service life. Additionally, the temperature and humidity of the environment have important effects on the operation of the repaired wheels. In this study, widely used 316L and 420 stainless steel alloy powders were selected as cladding materials, and three environmental conditions (25℃-RH60%, 50℃-RH60%, and 50℃-RH90%) were set according to changes in temperature and humidity in different areas of China. Friction and wear tests were performed under different temperature and humidity conditions on a damaged wheel after local repair by laser cladding. The results clearly show that there are demarcated equiaxed and directional columnar grain regions in the 316L cladding, whereas there are uniform plate and strip martensite structures in the 420 cladding, which are well formed by the metallurgical bonding of the wheel substrate. From 25℃-RH60% to 50℃-RH90%, the friction coefficient, plastic deformation thickness, and wear rate of the wheel–rail tended to decrease. However, the wear rates of the 420-coated wheels increased as the environmental conditions increased from 25°C-RH60% and 50°C-RH60%, and the wear rates of the corresponding rail samples remained high. The main forms of surface damage are fatigue cracks and material spalling. With increasing temperature and humidity, the damage to the bonding zone between the cladding and substrate surface decreases. The damage to the cladding profile is caused mainly by cracks at different angles and spalling pits. In the 25°C-RH60% environment, cracks initiate in the profile of the bonding zone and propagate along the plastic rheological line to the interior of the material. In comparison, the locally repaired wheel with 316L stainless steel alloy powder as the laser cladding material has better tribological properties and is more suitable for repairing damaged wheels.

Low-Energy Electron Beam Modification of Metallic Biomaterial Surfaces: Oxygen and Silicon-Rich Amorphous Carbon as a Wear-Resistant Coating.

Metallic biomaterials, such as cobalt chrome molybdenum (CoCrMo), Ti-6Al-4V, and 316L stainless steel are commonly used in orthopedic implant devices. Damage modes such as corrosion and wear are associated with the use of these alloys. One solution to limit wear and corrosion damage is to apply a surface coating to the medical device. In this study, using the low-energy electron beam (LEEB) of scanning electron microscopy (SEM), we induced a highly scratch-resistant oxygen and silicon-rich amorphous carbon film to grow on each of the above metallic biomaterials. LEEB interaction with adventitious surface carbon, silicone, and oxygen deposited on the above three alloys resulted in the layered-deposition formation (LEEB-LD) of a surface coating. Coating chemistry, morphology, and nano-scratch wear properties on each of the three alloys were characterized using atomic force microscopy (AFM) scratch testing and SEM/Energy dispersive spectroscopy (EDS) analysis. We hypothesized that LEEB-LD coatings could be deposited on these three metallic biomaterials with improved tribological properties than the underlying metal substrate. First, we generated coatings on all three biomaterials and documented the coating morphology (thickness and heterogeneity) and chemistry as a function of alloy, exposure time, and scan rate with coating thicknesses generated between 5 and 50 nm after 60 min of treatment, with each factor affecting the thickness. EDS maps showed high amounts of carbon, oxygen, and silicon in the modified surface which depended on the alloy (e.g., CoCrMo and SS had similar compositions while Ti had higher oxygen in the coatings). Coated and uncoated surfaces were then subjected to diamond scratch testing in an AFM at increasing force until the coating delaminated from the surface. Scratch-depth versus load and nominal Hertzian stress were plotted for both the uncoated and coated surfaces. We found that scratch depths were 40%, 75%, and 38% smaller on CoCrMo, Ti, and SS coatings, respectively, at the peak contact stresses tested (⍺ < 0.05), indicating higher hardness and wear resistance for the coatings. These results support the hypothesis that controlled thickness LEEB-LD oxygen and silicon-rich amorphous carbon coatings can be systematically generated using low-power electron beams and that these coatings have increased tribological (scratch-resistance) properties compared to the substrate metal.

Enhanced mechanical, tribological, and thermal properties of copper-graphene composites using additive manufacturing

Enhanced mechanical, tribological, and thermal properties of copper-graphene composites using additive manufacturing

Grain refinement of CoCrFeNiMn high-entropy alloy for improved high-temperature tribological properties

Grain refinement of CoCrFeNiMn high-entropy alloy for improved high-temperature tribological properties

Effect of Zr addition on microstructure, mechanical and tribological properties of Cu-Ni-Sn alloy fabricated by spark plasma sintering

Effect of Zr addition on microstructure, mechanical and tribological properties of Cu-Ni-Sn alloy fabricated by spark plasma sintering

Impact of vanadium (V) content on in-situ oxidation, high temperature mechanical strength and tribological properties of Al0.5CrFeNiVx high entropy alloys

In this study, four vanadium (V) containing high entropy alloys (HEAs) Al0.5CrFeNiVx (x=0.25, 0.5, 0.75, 1.0) were developed and investigated, in terms of examining the influence of V content on their microstructure, in-situ oxidation behavior, high temperature mechanical strength, and high temperature tribological performances. An increase in the V content causes precipitation of the Laves phase (VAl2) in the body-centered cubic (BCC) matrix. This structural transition increases the alloy hardness and compressive strength through solid solution strengthening, precipitation strengthening and grain refinement strengthening. When x is increased from 0.25 to 1, the maximum compressive strength increases from about 2476 to 3241MPa at room temperature and from about 521 to 797MPa at 700oC, respectively. In-situ oxidation investigation reveals that a higher V content accelerates the oxidation and provides a direct evidence of vanadium oxides melting at 700oC and thus forming the liquid oxide phases on the surface of HEAs. During high temperature tribological contact, the liquid oxide phases minimize the friction, allowing thicker and more complex oxide layers to form on the worn surface to improve the HEAs’ wear resistance. The findings in this work contribute to the development of novel HEAs with superior properties for potential applications that need outstanding mechanical strength, wear resistance, and thermal stability.

Enhancement of humid environment resistance and tribological properties of MoS2-based films by LaF3 doping

Enhancement of humid environment resistance and tribological properties of MoS2-based films by LaF3 doping

Effect of Cu content on the mechanical and tribological properties of MoN-Cu coatings deposited by HiPIMS

Effect of Cu content on the mechanical and tribological properties of MoN-Cu coatings deposited by HiPIMS

Effect of 3D interconnected Zr-BN based hybrid filler on the tribological properties of carbon fiber reinforced epoxy composites

The rapid growth of portable electronics requires a multifunctional composite with superior wear capability. Exceptional wear resistance is crucial for preventing early failure of laminated materials in harsh operating conditions. Hence, fabricating novel materials with excellent anti-wear performance is the primary objective in forthcoming integrated devices. The coefficient of friction (COF) and specific wear rate (Ws) of the fabricated composites were evaluated by tribo-test. The worn surface was analyzed using atomic force microscopy and field emission scanning electron microscopy. Incorporating the hybrid filler improved the wear performance of the corresponding composites. Compared to the CFRP composite, the COF and Ws of BN (60%)-ZrO2(40%)/carbon fiber/epoxy composite were reduced by ~56 and 92%, benefiting multifunctional thermal interface applications.

Tribological properties of cotton leaf extract as a natural lubricant additive

Tribological properties of cotton leaf extract as a natural lubricant additive

Nano-Al2O3 obtained the best tribological properties than similar hardness nanoparticles filled into epoxy resin

Nano-Al2O3 obtained the best tribological properties than similar hardness nanoparticles filled into epoxy resin

Synthesis of Plant-Based Ester for Metalworking Fluids and Tribological Performance

Lubricants derived from plant-based raw materials offer great potential for the development of environmentally friendly and renewable esters due to their easier and faster biodegradability, reducing dependence on petrochemical raw materials and creating new synthesis processes. The increasing burden of environmental regulations and the depletion of petroleum-derived raw materials have prompted many industries to opt for products based on natural raw materials. Due to these positive effects, vegetable oil-based esters have recently been considered as potential candidates for industrial use. In this context, ester synthesis from cottonseed oil, a natural biodegradable raw material source, was carried out by transesterification with isopropyl alcohol. The structure of the synthesized ester was elucidated by GC-FID and FTIR and important physical parameters such as acid number, saponification number, viscosity and density of the ester were investigated. The synthesized isopropyl cottonseed oil ester was used to formulate a synthetic metalworking fluid at concentrations of 2%, 4% and 6%. The tribological properties of the formulated metalworking fluid were evaluated using the Reichert test and the chip corrosion test. It was found that the addition of 6% isopropyl cottonseed oil ester to the synthetic metalworking fluid exhibited the best tribological properties.

Tribological Properties of Inconel 625 Alloy Reinforced by Biomimetic Shell-like Micro-texture with Double Texture Density Filled by SnAgCu

Tribological Properties of Inconel 625 Alloy Reinforced by Biomimetic Shell-like Micro-texture with Double Texture Density Filled by SnAgCu

Investigation of the Contact Characteristics of a Single-Nut Ball Screw Considering Geometric Errors

As the critical performance index of ball screws, the contact characteristics have a significant influence on the lubricant properties, tribological properties, and wear properties of ball screws, which further directly affect the service life of ball screws. The non-uniform load distribution induced by geometric errors results in imbalances among balls along the nut, negatively impacting the service life of ball screws. This study focuses on the load distribution of single-nut ball screws under low-speed working conditions. This paper proposes a self-adjustable model of load distribution that considers the flexibility of the screw and nut with respect to the determination of the non-bearing ball. A refined model for axial stiffness is proposed to systematically analyze the influence of geometric errors on stiffness variations under various loading conditions. The results confirm the ability of the proposed model to reveal the static load distribution in view of geometric errors. The greatest discrepancy observed between the theoretical predictions and the experimental data was 9.22%. The numerical simulations demonstrate variation trends in the normal contact load, the loaded-ball number, and the axial deformation of a nut with geometric errors. Furthermore, the relationship between the axial stiffness of a single-nut ball screw and the geometric error is obtained. The self-adjustable model of load distribution is helpful for studying the carrying capacity of a single-nut ball screw. The findings of the study provide a definite reference for optimization of structural design and wear life prediction.

Synthesis, Stability, and Tribological Performance of TiO2 Nanomaterials for Advanced Applications

The enhancement of tribological properties represents a pivotal strategy for achieving energy efficiency and environmental protection. Titanium dioxide (TiO2) nanomaterials have been garnering significant attention due to their exemplary tribological properties and due to the abundance of titanium reserves. The present review is concerned with the study of TiO2 nanomaterials in lubricants. The properties and various synthesis methods of TiO2 nanomaterials are presented. The dispersion stability of these TiO2 nanomaterials in lubricating oils is discussed in depth, as well as strategies to improve their dispersion stability, such as enhancing compatibility with base oils, reducing the dynamic light scattering (DLS) particle size, modulating the zeta potential, and optimizing the drying step. Aggregation and dispersion instability remain key challenges for TiO2 nanomaterials, especially bare TiO2 nanoparticles (NPs). In contrast, in situ surface-modified TiO2 NPs show improved stability and tribological performance, offering promise for further research. The tribological performance of lubricants has been demonstrated to be enhanced by TiO2 nanomaterials, with the observed enhancement attributed to the synergistic effect of multiple mechanisms, including rolling, patching, polishing, and the formation of a protective film. Furthermore, future research suggestions are proposed to provide a reference for the design and synthesis of high-performance TiO2 nano-lubricants and promote their wide application.

Microstructural and tribological characterisation of an 3D printed Ti-6Al-4V alloy under annealing treatment for prosthetic implantation

Annealing treatments was implemented on a laser powder bed fusion-processed (LPBF) Ti-6Al-4V (Ti Gr23) alloy to improve its tribological attributes. Wet reciprocating wear tests at 5 N normal load and sliding velocities (5 mm/sec) were utilised to evaluate their wear behavior. The test was performed using a SS304 spherical ball of diameter 5 mm and a stroke length of 5 mm in simulated body fluid (SBF) at body temperature. A set of optimal process parameters were used for the fabrication of porous less Ti64 sample using porosity parametric simulation in Additive ANSYS software. The microstructural and mechanical characterization were performed and corelated wear mechanism. The results indicate that the partial decomposition of α’→α + β occurred during the annealing treatments. A needle-like martensite α’ phase was noticed on the as-sintered sample. The worn morphologies and mechanisms depend significantly on the microstructural characteristics while microstructural characteristics depend significantly on annealing treatment. Scratches observed along the wear track of Ti64 alloy, accompanied by islands of microscopically smooth oxide layers detaching from the surface, suggest a mixed mode of wear characterized by both abrasive and adhesive mechanisms. Annealing treatment was improved the tribological behaviour of Ti64 alloy.

Tribological performance and 3-D surface characterisation of age-hardened Al2090-based ceramic composites

This study investigates the synergistic influence of boron nitride (BN) tertiary ceramic additives and age-hardening treatment on the microhardness and wear resistance of Al2090-based hybrid composites, fabricated using the stir casting method. X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) studies are carried out to assess the phases present, microstructure, and surface properties, respectively. The metallurgical investigations confirm a relatively superior uniformity in the distribution of particles and the ageing of precipitation at 150°C, vis-à-vis the other temperatures explored in this study. The experimental examinations conducted as per ASTM (E8 and G99) standards revealed a significant improvement in both the hardness and the primary tribological properties, when micron-sized boron carbide, graphite, and boron nitride were used as reinforcements. Age-hardened samples, especially the hybrid composite HS-2 with 5 wt.% each of boron carbide, graphite, and boron nitride, demonstrated an enhanced hardness of 25.23% and lower surface roughness (44.3 nm) compared to Al2090 (AS), due to the presence of load-bearing ceramic reinforcements. Increasing the applied load led to higher wear rates and coefficients of friction for Al2090. However, heat-treated hybrid metal matrix composites (HMMCs) exhibited a contrary behaviour, suggesting enhanced durability. The investigation highlighted the better wear resistance of heat-treated and near-optimally reinforced HMMCs, indicating their potential candidature for wear-resistant aerospace applications.