In order to investigate the turbulent lubrication performance of a textured hydrodynamic journal bearing (THJB), a model of turbulent lubrication was established in this paper. The variations in the Reynolds number, oil film thickness, oil film pressure, bearing capacity, attitude angle, and side leakage flow with structural and working parameters were studied, and the axis whirl orbit was further analyzed. The results show that turbulent lubrication is suitable for the actual operating conditions of THJBs. The Reynolds number decreases with the eccentricity ratio in the pressure-bearing zone but increases with rotational speeds, whereas the variation in the maximum oil film pressure increases and the minimum oil film thickness decreases with the eccentricity ratio under various Reynolds numbers. The bearing capacity decreases with the dimple diameter, depth, oil film thickness, and clearance ratio but increases with the length/diameter ratio and dimple spacing. As the eccentricity ratio increases, the attitude angle decreases, but the side leakage flow increases. In addition, the system tends to be unstable as the rotational speed and length/diameter ratio increase, and the friction and wear on the surface are three-body friction. This work not only helps in analyzing the characteristics of a THJB under actual operating conditions but also provides support for research on the simulation of THJB’s lubrication mechanism of THJB via computational fluid dynamics.

In this paper, the effect of micro-dimple textures (produced by a laser) on the tribological properties of bearings is investigated. This study offers guidelines to reduce the friction torque of the bearing pair and addresses the problem of difficult start-ups after shutdowns. Micro-pits with different texture diameters and depths were machined on the surface of journal bearings. Then, the impact of several different texture parameters on the tribological performance of the bearing pairs was studied using an orthogonal experimental design. Subsequently, the surface morphology of the bearings before and after the friction and wear test was observed using scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). These observations were then used to determine the type/state of friction and wear, which also improves our understanding of how texture affects the service life of bearings. The results indicate that the bearings’ micro-pit surface hardness follows an approximate parabolic spatial distribution that decreases along the micro-pit wall. Furthermore, the laser processing of surface textures was found to cause hardening in certain areas, and the chemical composition of elemental carbon and oxygen at the inner surface of processed bearings increased by 31.1% and 7.9%, respectively. Moreover, abrasive wear was identified as the primary form of wear. The textured surface’s antifriction mechanism primarily functioned to trap particles, which acted as a secondary lubrication source and altered the lubrication states by serving as a medium for supplied lubricants. The results confirm that a suitable selection of texture parameters can not only effectively reduce the friction coefficient without shortening the service life of the bearing pair but also facilitate the smooth start-up of the rotor–bearing system.

In order to evaluate contact characteristics, a modified contact model was proposed considering the deformation characteristics of asperity bodies, and the variation rules of wear rate with fractal dimension, material property constant and debris probability were established. The results show that the actual contact area increases with an increase in load when the surface topography is constant, whereas the contact area decreases with an increase in characteristic scale coefficient if the fractal dimension or load is constant. For running-in wear, the wear rate increases with an increase in surface profile parameters under the same contact area. In addition, the wear rate increases with an increase in actual contact area when the surface profile parameter is constant. Regarding abrasive wear, the wear rate is the smallest when the fractal dimension is 1.6. The wear rate increases with an increase in contact area under the same characteristic scale coefficient, but decreases with an increase in the characteristic scale coefficient under the same contact area, and the smaller the material constant and the larger the probability constant, the higher the wear rate. The establishment of this model provides a basis for further study of the tribological properties of the contact surface.

As a renewable fuel for diesel engines, biodiesel plays a significant role in improving the lubricating performance of low-sulfur diesel. The decline in lubricity of low-sulfur diesel can lead to increased friction and exacerbated wear on the surfaces of diesel engine friction pairs, whereas the addition of biodiesel can effectively mitigate such tribological issues. In this study, tribological performance tests of biodiesel-fueled engines were conducted, combined with molecular simulation methods. Using Materials Studio software, the adsorption behavior and dynamic processes of three typical fuel components: C₇H₁₆, C₁₁H₂₂O₂, and C₁₉H₃₆O₂, on the α-Fe (110) crystal surface were simulated. This systematically revealed the mechanism by which biodiesel improves friction and wear performance. The results indicate that biodiesel significantly enhances the lubricating properties of low-sulfur diesel. The carbonyl groups in biodiesel molecules exhibit high reactivity, demonstrating larger absolute values of adsorption energy and cohesive energy compared to alkane components, which indicates stronger surface adsorption capacity. This facilitates the formation of a stable and continuous lubricating film on metal surfaces, thereby providing anti-wear and friction-reducing effects, ultimately improving the wear resistance of key components in diesel engines.

Purpose: This study aims to address the issues of lubrication failure and poor wear resistance that traditional coatings often exhibit under service operating conditions. Design/methodology/approach: A textured FeCoCrAlCuNi high-entropy alloy (HEA) coating was fabricated on bearing surface via a combination of surface texturing and plasma spraying, and its properties including phase composition, microstructure, elemental distribution, hardness and tribological properties were characterized by using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy as well as friction and wear tester. Findings: The textured FeCoCrAlCuNi HEA coating was composed of FCC and BCC phases. The interfacial bonding strength depends on the mechanical interlocking, and the average hardness was 266 HV about 1.2 times that of substrate, while the wear rate was reduced to two-thirds of that of substrate. A transition in the wear mechanism from abrasive to fatigue wear with varying loads, whereas the wear resistance was governed by a synergistic effect between in-situ formed Al2O3/Cr2O3 oxide films and surface texturing. Originality/value: The tribological properties of the textured FeCoCrAlCuNi HEA coating were significantly improved by improving interfacial bonding strength, regulating lubrication behavior and inducing the formation of protective oxide film. An effective strategy for designing wear-resistant coatings under operating conditions were provided by this work. Peer review: The peer review history for this article is available at: Link to the cited article.