As a solid lubricating material, WS.sub.2 composite coating plays an important role in the lubrication of spacecraft rotating parts. However, spacecrafts will face high temperature and humid ...atmospheric environment during launch, and their WS.sub.2 composite coating is thus prone to oxidation failure, which limits its engineering application. Here, a new type of WS.sub.2 composite coating was successfully prepared through doping rare earth. The prepared coating showed excellent high temperature tribological properties in atmospheric environment. The mechanism that rare earth doping can improve the high temperature tribological properties of WS.sub.2 composite coating was revealed by high temperature tribological test, XPS, Raman, and other analysis methods. The results suggest that the synergistic effect of rare earth oxide and WS.sub.2 at high temperature leads to excellent tribological properties, which will lay a foundation for the effective application of WS.sub.2 composite coating in spacecraft rotating parts.
The triboelectric effect has long been understood as the phenomenon of electric charge transfer resulting from mechanical contact. Although this has long been observed in a multitude of ...circumstances, ranging from daily life to specific engineering applications, a significant knowledge gap remains regarding the mechanisms that describe triboelectric charge transfer. Research into the triboelectric effect has however seen a recent surge in the previous decade, owing to the conception of the triboelectric nanogenerator (TENG) and its subsequent applications in energy recycling and self-powered sensing. Existing research now entails various models for predicting the output of TENG devices from an electrical engineering standpoint, in addition to qualitatively describing the mechanisms that drive triboelectric charging. However, many of these models fall short with regards to describing the role of tribological factors in these physical mechanisms. Similarly, the field of tribology has only recently begun to expand its interests into triboelectric phenomena. This research plays a key part in discerning the influence of tribology on triboelectric mechanisms and applications. Factors such as surface composition, contact topography, normal and tangential forces, and relative motion are determined, as well as the effects of material wear and the presence of contaminating media. This is achieved primarily through the modification of a mechanical testing apparatus with the integration of a high-impedance electronic measurement circuit for the correlation of mechanical and electrical measurements. Ultimately, a semi-analytical model is also constructed using these data as a way of providing a stepping stone towards a fundamental understanding of all aspects of the triboelectric effect.
The performance of rolling bearings is often reduced due to the additional wear introduced by sliding contact. Therefore, it is very vital to study the evolution of the sliding wear process of the ...bearing material friction pairs. The tribological performance of the two kinds of material pairs, including GCr15-GCr15/Si.sub.3N.sub.4-GCr15, was analysed under oil-lubricated conditions with a pin-on-disc rig. The results show that with high initial surface roughness, the friction coefficients of the two pairs decrease as the load and speed increase, while in the stable wear stage, Si.sub.3N.sub.4-GCr15 friction pairs show better tribological properties than those of GCr15-GCr15 friction pairs. For lacks of information-rich studies and techniques of worn surfaces topography, an in-suit 3D microscope is adopted to obtain the topographies of friction and wear surface during the wear tests. The results prove that 3D topography can clearly characterize the wear process. 3D topography shows identical trend with the surface roughness (R.sub.a, S.sub.a and S.sub.q) and the friction coefficients. Citing mixing parameter S.sub.dr explores its feasibility for characterizing worn surfaces. The results illustrate that there is a close relationship between S.sub.dr and 3D topography, which can reflect the friction transition of a surface from running into severe wear. A low surface roughness indicates a small S.sub.dr.
An introductory reference focusing on the key concepts and engineering implications of tribology, the book brings together the relevant knowledge from different fields needed to achieve effective ...analysis and control of friction and wear. Updated to cover recent advances in tribology, this new edition includes new sections on ionic and mesogenic lubricants, surface texturing, and multiscale characterization of 3D surfaces and coatings. Current trends in nanotribology are discussed, such as those relating to lubricants, coatings and composites, and geotribology is introduced. This book offers a comprehensive overview of the mechanisms of wear, lubrication and friction in an accessible manner designed to aid novice engineers, non-specialists and students; Provides a reader-friendly approach to the subject using illustrations to break down the typically complex problems associated with tribology; and ncludes end-of-chapter problems to test understanding, with solutions provided.
In this paper, the tribological behavior of Cu-SiOsub.2 composite against 1045 steel was studied. Based on the characterization of worn surface, worn subsurface and wear debris in morphology and ...composition, the friction layer effects on the tribological behavior of coupled materials and the wear mechanism were discussed. Abrasive wear and adhesive wear are the dominant mechanisms at the 0.56 m/s–1.12 m/s condition. Delamination wear and oxidation wear are the dominant wear mechanisms at the 1.68 m/s–2.24 m/s condition. Plastic and thermal deformation cause the evolution in morphology and structure of the tribolayer of Cu-SiOsub.2. There is a certain correlation between the friction coefficient and the variation in friction temperature during sliding wear of Cu-SiOsub.2 and 1045 steels. The addition of SiOsub.2 induces the accumulation of frictional heat at the friction interface, which leads to an increase in the average temperature of the contact surface and transfer.
Tribología: pasado, presente y futuro Santa-Marín, Juan F.; Toro-Betancur, Alejandro
Tecno - Lógicas (Instituto Tecnológico Metropolitano),
08/2015, Letnik:
18, Številka:
35
Journal Article
Odprti dostop
La tribología es la ciencia que estudia fenómenos de superficie tales como fricción, desgaste, y lubricación. Es un campo multidisciplinar que incluye áreas como la ciencia y tecnología de ...materiales, ciencia y tecnologías químicas, biología y biomedicina y una variedad de áreas temáticas tales como diseño, mecánica de sólidos, mecánica de fluidos, termodinámica, lubricación, metalurgia, entre otras.
Electrospark coatings alloyed with MoSsub.2 have been studied. The coatings were obtained by the following two strategies: the first consisted of pre-applying molybdenum disulfide to the treated ...surface and alloying with a molybdenum electrode (Mo + MoSsub.2 coating); the second consisted of applying a paste with a sulfur content of 33.3% to the treated surface and alloying with a molybdenum electrode (Mo + S coating). The structure, phase composition, and tribological properties of the coatings were investigated. The coatings have a complex structure consisting of an upper soft layer, a hardened white layer, a diffusion zone, and a substrate. Element analysis and cross-sectional hardness changes indicated that element diffusion occurred at the coating/substrate interface. The phase composition of the coatings is represented by BCC and FCC solid solutions on Fe, and MoSsub.2 is also detected. In Mo + S coatings, the molybdenum disulfide on the surface is about 8%; in Mo + MoSsub.2 coatings, it is 27%–46%. The obtained coatings show very good tribological properties compared to molybdenum ESA coatings. The frictional forces and coefficients are reduced by a factor of 10 and 40, depending on the test conditions.
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