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The energy transition and dissipation of atomic-scale friction are investigated using the one-dimensional Prandtl-Tomlinson model. A systematic study of the factors influencing the energy dissipation is conducted, indicating that the energy that accumulated during the stick stage does not always dissipate completely during stick-slip motion. We adopt the energy-dissipation ratio (EDR) to describe...
In this study, we evaluated the wear properties of four brands of brake pad available in the Nigerian market. In particular, we assessed the tribo performance and service life of the brake pads. We purchased four commercial brands of brake pads used in light duty cars and coded them as AU, SN, TY and SM, respectively. A small piece of the brake pad lining materials was carefully chiseled from the...
This paper reports a series of studies on the lubricant properties, elastohydrodynamic film thickness, and coefficients of friction of several commercially available ester base stocks, i.e., diisooctyl phthalate (DIOP), diisodecyl phthalate (DIDP), diisotridecyl phthalate (DITDP), diisooctyl sebacate (DOS), diisotridecyl sebacate (DTDS), trihydroxymethylpropyl trioleate (TMPTO), and pentaerythritol...
Tribocorrosion is a degradation mechanism resulting from the interaction of mechanical (wear) and chemical (corrosion) phenomena. This interaction leads to surface damage that does not correspond to the simple sum of wear and corrosion taken separately. Testing tribocorrosion of material pairings thus requires the capability not only to control the mechanical and chemical test parameters but also...
In this study, the effects of deep cryogenic treatment (DCT) on the mechanical and tribological properties of AISI D3 tool steel were investigated together with a systematic correlation between their hardness and wear resistance. It was found that conventionally heat treated AISI D3 tool steel samples were significantly hardened via an additional DCT, which was attributed to the more retained austenite...
Despite continuous improvements in machine elements over the past few decades, lubrication issues have impeded human exploration of the universe because single solid or liquid lubrication systems have been unable to satisfy the ever-increasing performance requirements of space tribology. In this study, we present an overview of the development of carbon-based films as protective coatings, with reference...
Using an MFT-R4000 tester at room temperature, the leaf-surface wax of two desert plants, Ammopiptanthus mongolicus (AM) and Reaumuria soongorica (RS), was extracted and evaluated for its potential as a lubricant additive in polyalphaolefin (PAO) for steel-steel contact. Gas chromatography-mass spectrometry analysis was performed to identify the composition of the AM leaf-surface wax, and scanning...
The suitable brake torque at the shoe-drum interface is the prerequisite of the active safety control. Estimation of accurate brake torque under varying conditions is predominantly the function of friction coefficient at the shoe-drum interface. The extracted friction coefficient has been used in the antilock braking system (ABS) algorithm to plot the μ-slip curve. The longitudinal forces like Coulomb...
Since the term “superlubricity” was put forward at the beginning of 1990s, it has become one of the hottest researches in tribology due to it being close linked to the energy problems. Recently, the International Workshop on “Superlubricity: Fundamental and Applications” was successfully held on 19–20 October 2015 in Beijing, which has attracted many researchers in this field. The recent scientific...
This investigation reports on the effect of Jatropha oil doped with lube oil on tribological characteristics of Al-7%Si alloy. The factors involved were Jatropha oil percentages, sliding velocities and load which was optimized for weight loss, friction coefficient and specific wear rate characteristics. The conventional lubricant was SAE 40. It is observed that the Jatropha oil percentage factor had...
Magnetorheological (MR) fluid damper which allows the damping characteristics of the damper to be continuously controlled by varying the magnetic field is extensively used in metal cutting to suppress tool vibration. Even though magnetorhelogical fluids have been successful in reducing tool vibration, durability of magnetorhelogical fluids remains a major challenge in engineering sector. Temperature...
Polyether ether ketone (PEEK) is a high-performance thermoplastic, which is often selected for hightemperature tribological applications under chemically aggressive environments. The present work investigates the tribological behavior of a high-performance PEEK composite under conditions that are often found inside hermetic compressors. Therefore, an AMTI tribometer equipped with a hermetic chamber...
The oil viscosity specification for wind turbine gear oils is ISO VG 320, although there are quite different viscosity indexes oils for that viscosity specification. This work evaluates the behaviour of different base oil formulations, since polyalphaolefin (PAO), mineral, ester and polyalkeleneglycol (PAG) that withstand quite different viscosity indexes. The oils evaluation was done in rolling bearing...
It has been shown before that liquids can slip at a solid boundary, which prompted the idea that parallel-surfaces bearings can be achieved just by alternating slip and non-slip regions in the direction of fluid flow. The amount of slip at the wall depends on the surface tension at the liquid–solid interface, which in turn depends on the chemical state of the surface and its roughness. In the present...
Superlubricity means non-sticky and frictionless when two bodies are set contacting motion. Although this occurrence has been extensively investigated since 1859 when Faraday firstly proposed a quasiliquid skin on ice, the mechanism behind the superlubricity remains uncertain. This report features a consistent understanding of the superlubricity pertaining to the slipperiness of ice, self-lubrication...
Hydrostatic assistance is a commonly used method to improve limited load carrying ability of tiltingpad thrust bearings during transient states of operation of vertical shaft hydro-generators. Despite of special hydraulic equipment (as pumps, valves, etc.), it also requires manufacturing of special recesses/pockets at pad sliding surfaces, into which oil is injected under high pressure. It allows...
The ester base oil of dioctyl adipate (DOA) was oxidized in an oven at 200 °C for 30 h, and variations in the physicochemical and tribological properties were studied. To investigate the thermal-oxidation mechanism, the thermal-oxidation products were analyzed by gas chromatography–mass spectrometry (GC−MS), and the thermal-oxidation process was simulated using visual reactive force field molecular...
In this study a wear track was generated on aluminium by rubbing it against a hard steel ball. The generated wear track has a typical depth of 50 μm and exhibits marked ridges on its borders. The cross section profiles were measured using two different stylus profilometers equipped either with skidless or skid probes and compared to a skidless reference instrument. It was found that the use of a skid...
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