Runyi Ma

This work is a theoretical study aimed to address the lubrication failure of Tom-Pac TP-2557 gel lubricant on the textured high-entropy alloy coatings (THEACs) under wide-temperature-range operating conditions; the rheological lubrication properties of the surface are investigated in this work. Based on lubrication theory and non-Newtonian fluid mechanics, a gel lubrication viscosity model considering temperature dependence and a thermo-mechanical coupled constitutive relationship for the THEACs are established. The results show a significant shear-thinning behavior of the gel within a moderate low-to-medium temperature range, and the onset temperature of thermal degradation is identified. Optimal geometrical and distributional parameters of the surface textures, along with a favorable surface energy range, are determined to achieve desirable interfacial shear strength. Moreover, an anchoring-slip synergistic mode arising from surface energy heterogeneity is found to further enhance lubricating film stability. This research provides a theoretical basis for the gel lubrication design of the THEACs.

This paper presents a cross-scale model for predicting the tribological behavior of textured coatings made of high-entropy alloys. The research methodology includes molecular dynamic modeling, a modified fractal surface model, and the Green’s method with fast Fourier transform. The main results demonstrate the existence of an optimal range of parameters: a fractal dimension of 2.45–2.55 and a texturing density of 15–20%, which reduces the coefficient of friction to 40% compared with untextured surfaces. The practical significance of the work lies in the creation of a theoretical basis for the integrated design and forecasting of the tribological properties of high-entropy coatings.

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.