The laser surface texture process will inevitably produce the edge of material surface texture bulges. Currently, laser processing bulges are generally polished directly, but this method ignores its impact on the friction pairs. In this paper, the tribological properties of polished and unpolished textured surfaces were investigated under dry friction, oil lubrication, and seawater lubrication conditions using three shapes of texture (grooves, square pits, and round pits) prepared on the surface of 316L stainless steel. The results show that the polished surface of 316L stainless steel texture increases wears, and the friction mechanism is mainly adhesive wear, while the unpolished surface of the texture has less wear, and the friction mechanism is mainly abrasive wear. The method and principle of using machining bulges to improve the wear resistance of friction pairs are discussed to address the differences in the tribological performance of entire friction pairs due to the influence of machining bulges of different shapes of texture.
The molecular structure of lubricating oil affects its lubrication properties, catalytic and hydrolytic stability, and anti-wear properties. Based on the idea of material genomics, researchers are trying to find the correlation between structural characteristics and functional performances of lubricating oil, but the correlation can only explore the influence weight of structural parameters on performance, it is also very important to research the influence mechanism. In this study, through quantum mechanics/molecular mechanics calculations, (i) the spatial configurations of four typical ester lubricants with different chain length structures were studied, (ii) effects of active functional groups and charge distribution on the properties of the ester lubricants were discussed, and (iii) electronic transition and molecular orbital contributions were compared. The calculated results are expected to provide considerable support for theoretical research on the anti-wear and anti-oxidation mechanisms of ester lubricants and assist the rapid design, development and application of lubricating materials.
Reducing wear and clarifying relation mechanism are essential to improve the life of engine bearings, so we investigate the influence of ambient temperature on the friction characteristics of M50 steel self-matching pairs under dry friction conditions. As the ambient temperature increases from 30 ℃ to 500 ℃, friction coefficient decreases sharply from 0.78 and tends to be stable around 0.4, while wear rate firstly decreases and then increases. High temperature (More than 300℃) induces the serious oxidation and softening on the wear surface, causing the main wear mode from abrasive wear to adhesive wear. The oxides include mainly of Fe2O3 and Fe3O4, and minor MoO3 and Cr2O3, which are benefit for forming a continuous tribolayer on the wear surface, thereby improving the friction performance.
Recycled aluminum will be a significant material choice for automobile body stamping because of its recyclability and low cost. In this paper, the cupping tests and tribological tests were used to study the evolution of defects in forming process and its influence on the properties of recycled aluminum alloy, Failure mechanisms of recycled aluminum alloy were analyzed, as well as the interaction between different lubricant additives and defects under oil lubricating conditions. According to the results, the defects of the recycled aluminum alloy, especially the impurity phase particles, can have negative effects on the properties of the sheets. The impurity phase particles are brittle and are prone to fracture, resulting in stress concentration. In addition, the binding with the matrix is weak, which destroys the continuity and leads to surface strain in the process of material flow, thus adversely affecting the quality of the cup. By physical adhesion and filling of the depressions, MoS2 solid lubrication additive improves forming and friction performance of the cup. The present study indicates how defects affect the cupping properties of recycled aluminum alloys, and it provides a theoretical basis for the improvement of the stamping lubrication process of recycled aluminum alloys.
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