Papers by Keyword: Tribological Behaviour

Abstract: The influence of Al/Ti and Al/Cr ratios on the structural, mechanical and tribological properties of AlTiSiN and AlCrSiN coatings, deposited by the cathodic arc evaporation PVD method at a temperature of 400°C, was investigated. The remains of the original AlSiN hexagonal phase were observed in the obtained coatings as well as the crystallites of cubic TiN and CrN, respectively. XPS analysis assumes the presence of a substoichiometric SiN. The addition of 11 at.% Ti or 13 at.% Cr in AlSiN led to an increase in both the coating’s resistance to plastic deformation and the plasticity index. The addition of 13 at.% and 24 at.% Cr to the AlSiN coating structure resulted in a decrease in the average coefficient of friction with 18% and 36% against a counterpart of Al₂O₃, respectively, and with 36% for both concentration against steel ball counterpart. The addition of Ti have no influence on the values of the coefficient of friction at using ceramic counterpart, while at steel counterpart decreased it up to 30%. Both element change the abrasion effect of the coating.Keywords: AlCrSiN; AlTiSiN; Cathodic Arc Deposition; Tribological Behaviour; Abrasion Resistance; Nanoindentation

Abstract: A pre-cleaning and an electroless nickel plating (EN-HP) were applied to copper foil to improve its tribological behaviour and corrosion resistance. The coating porosity was measured by the corrodkote, tribological behaviour was measured with microhardness tester and a CSM ball-on-disk tribometer, corrosion resistance was measured by potentiodynamic polarization in 3.5 wt.% NaCl solution. Matte nickel plating (mNi) and moderate compact Ni–P coating (EN-MP) were made as comparisons to EN-HP in those tests. By deposition of EN-HP, both coating porosity and tribological behaviour are greatly improved compared to mNi, and the corrosion resistance is distinctly ameliorated to the comparisons. Above research demonstrates that the copper foil with EN-HP coating is good underlay in assemblage of machine.

Abstract: Four ionic liquids containing dithiocarbazate were synthesized. Their antiwear and friction-reducing properties of these synthetic liquid compounds as the lubricants of a steel/steel contact were examined using an Optimol SRV oscillating friction and wear tester in ambient condition. The results indicated that the ionic liquids containing dithiocarbazate as the lubricants showed excellent friction-reducing and antiwear properties for the steel/steel pair. The introduction of the dithiocarbazate group into the molecules of the ionic liquids contributed to improve the tribological behaviour.

Abstract: Molybdenum disulphides (MoS2), which belong to the family of transition metal dichalcogenides, are well known for their solid lubricating behaviour. Thin films of MoS2 exhibit extremely low coefficient of friction in dry environments, and are typically applied by mixed in oil, grease or impregnated into porous matrix of powdered materials, sputter deposition, pulsed laser ablation, evaporation or chemical vapour deposition and, which are essentially either line-of-sight or high temperature processes. Solid lubricant coatings are attractive because they can reduce friction-generated heat. MoS2 is a common solid lubricant. However, the use of MoS2 can limited by excessive wear, as well as a friction coefficient. Several studies on solid lubricant coatings demonstrated success in lubricating dry sliding contacts over very long periods in tribometer tests or reciprocating sliding experiments.Several pellet-on-disk and pad-on-disk tribometer tests were conducted to study the lubrication characteristics of third-body particles of MoS2 powder. The tests consisted of simultaneous pellet-on-disk and pad-on-disk sliding contacts. Results from the tests show the self-repairing, self-replenishing, oil-free lubrication mechanism of MoS2. A theoretical control volume fractional coverage (CVFC) model was developed to predict: - (1) the friction coefficient at the pad-on-disk interface and - (2) the wear coefficient for the lubricated pellet-on-disk sliding contact. The fractional coverage varies with time and quantifies the amount of third-body film covering the disk asperities. Results from the model capture the tribological behaviour of the experimental sliding contacts reasonably well. The aim of this paper is modeling and experimentation of solid lubrification with MoS2 particles through self-repairing and self-replenishing and through the comparision between theoretical and experimental results obtained in the process of friction and wear by tribological tests.

Abstract: Effect of carbon nanotube(CNT) on structure, strength and tribological behavior of CNT/PU composites is studied in the filler range of 5 vol%. It is found that differences in filler content used to determine the type of structure evolved and patterns of variation of mechanical properties, friction and wear in response to increasing filler content. It is found that wear of low-filled CNT/PU composites is dominated by delamination mechanism and wear resistance changes correlate with structural transformations of the composites. The maximum increase in wear resistance of the PU composites is reached at 2 vol% filling.

Abstract: The effects of PTFE on the tensile and tribological properties of glass fiber reinforced polyamide 6(PA6) composites were studied. Tribological tests were conducted on an M2000 friction and wear tester using a block-on-ring arrangement. It was observed that the PTFE played a main role in the tensile-resistant and wear-resistant properties of the PA6 composites. The tensile properties were ruled by the fiber–matrix adhesion. And the excellent tribological performance of the PTFE fillers improved the tribological properties of PA6 composites.

Abstract: An interfacial polymerization method for polyacrylate resin was adapted to fabricate nanocomposites with nano-SiO2 particles via in situ polymerization. The tribological behaviors of the nano-SiO2 nanocomposites are briefly discussed in terms of types of functionalization and nanoparticle loading. Nano-SiO2 functionalization with three silanes improved the nanoparticles interfacial interaction and compatibility in the nanocomposites, resulted in lower friction coefficient and wear mass. And the results of DSC also testified that. The wear mass and friction coefficient of the nanocomposite containing 3 wt% nanoparticles with KH570 silane are 50.8mg and 0.20, respectively. Results of RCA show that the incorporation of the nano-SiO2 into the polyacrylate resin improves the scratch resistance significantly. Results of SEM indicate that the neat polyacrylate resin is dominated by adhesive wear, going with tearing resin, while all nanocomposites containing 3 wt% nanoparticles with silane are dominated by particle adhesive, going with soft adhesive wear.

Abstract: Silica nanospheres with good dispersibility in oily solvents were prepared using a facile in-situ surface-modification route. The microstructure of resultant surface-capped silica nanospheres was analyzed with a transmission electron microscope. The tribological behavior of the silica nanospheres as additive in engine oil SE 15W/40 was evaluated using a four-ball machine; and the morphology and composition of the worn steel surfaces were analyzed using a scanning electron microscope equipped with an energy dispersive X-ray analysis attachment. It was found that organic modifier hexamethyldisilazane (HMDS) was combined with nano-SiO2 by covalent bonds, resulting in varied surface properties and improved dispersibility of the nanoparticles in many organic mediums. Besides, oil-soluble silica nanospheres as additive in the engine oil had excellent friction-reducing and antiwear abilities, showing promising application prospect.

Abstract: Ni-P-PTFE composite coating was prepared by electroless plating based on the Ni-P coating technology. The effects of surfactant and PTFE content on the binding force, hardness, friction coefficient, wear rate and content of PTFE particles of the composite coating was investigated. In addition, the tribological behaviors of composite coating were discussed. The surface morphology and microstructures of composite coating were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), and the wear mechanism of composite coating was analyzed by using the MRH-3 friction and wear tester. The results indicated that the Ni-P-PTFE composite coating prepared under the optimum process condition exhibited excellent friction properties, and the wear mechanism is manifested as adhesion and slight grain-abrasion during the abrasion.

Abstract: A relatively new process called microarc oxidation (MAO), also called plasma electrolytic oxidation (PEO), has emerged as a unique technique to produce hard, thick ceramic oxide coatings on different Mg or Al alloys. The magnesium offers various possibilities of application in industry, but its poor property in corrosion resistance, wear resistance, hardness and so on, limited its application. Through microarc oxidation, ceramic coating is directly formed on the surface of pure magnesium, by which its surface property is greatly improved. In this paper, a dense ceramic oxide ceramic coating was prepared on the magnesium by microarc oxidation in a Na2SiO3-Na2WO4-KOH-Na2EDTA electrolytic solution. The surface morphology of the coating was observed by the Scanning Electron Microscope (SEM). Using the X-ray diffraction (XRD), the phase structure of the coating was analyzed. The friction and wear behavior of the micro-arc oxidation ceramic coating under dry sliding against GCr15 steel was evaluated on a ball-on-disc test rig. The results showed that the magnesium was characterized by adhesion wear and scuffing under dry sliding against the steel, while the surface micro-arc oxidation ceramic coating experienced much abated adhesion wear and scuffing under the same testing condition. The micro-arc oxidation ceramic coating showed good friction-reducing and fair antiwear ability in dry sliding against the steel.