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The rate of wear of cam followers in a valve train system is mainly a function of contact stress between the cam and the follower, sliding velocity and hydrodynamic film thickness between the two mating surfaces. The problem of surface fatigue wear becomes severe as the contact between cam and follower exceeds the plasticity limit of material. It finally leads to an increase in valve lash and loss...
Carbon films (∼2μm thick) with a range of mechanical properties and underlying substrate roughnesses were evaluated for delamination and wear under conditions of combined impact and sliding contact. One-side-coated and both-sides-coated titanium alloy pin and disk wear couples were assessed using a custom-made impact/sliding pin-on-disk apparatus in a colloid-based blood volume expansion medium. The...
This paper studies the continuous friction behavior of carbon–carbon composites (C/C) fabricated by the coal tar pitch densification process. In the densification process, different numbers of densification cycle are adopted to investigate the influence on physical properties, mechanical properties, microstructure and friction behavior. Experimental results indicate that open porosity decreases with...
In this research, the wear of electroless Ni–P and Ni–P–B 4 C composite coatings was reviewed. Auto catalytic reduction of Ni in nickel sulfate and sodium hypophosphate bath including suspended B 4 C particles with different concentration was used to create composite coatings with 12, 18, 25 and 33vol.% of B 4 C particles. Coatings 35μm thick were heat treated at 400°C for...
In this study, abrasive wear behaviors of gas carburized AISI 8620 steels with different case depths were examined. AISI 8620 steels yield excellent carburizing results and are used in manufacturing of gears. Two carburized and quenched specimens with different case depths were produced. Specimens were prepared at HEMA Gear Factory. Wear tests were carried out using pin-on disc test machine. Specimens...
The thermal contact resistance phenomena are increasingly important as the size of mechanical and electronic components decrease. Applying a coating material with high thermal conductivity is an effective way to enhance the thermal contact conductance. This work conducted an experimental and theoretical study to investigate the effects of diamond film coatings on the thermal contact conductance. A...
A molecular dynamics simulation is used to investigate the effect of surface roughness on the nano-rheology of ultra-thin films confined between two solid walls. The results show that friction is sensitive to the confining surface morphology and the fluid molecules near the two confining surfaces are in a layering solid-like structure. At a high shear rate, the interfacial layers of the film stick...
The tribological behaviour of TiCN coating prepared by unbalanced magnetron sputtering is studied in this work. The substrates made from austenitic steel were coated by TiCN coatings during one deposition. The measurements were provided by high temperature tribometer (pin-on-disc, CSM Instruments) allowing measuring the dependency of friction coefficient on cycles (sliding distance) up to 500°C. The...
The microstructure and wear behavior of WC–8TiC–3TaC–8Co cemented carbide and Cu–Zn–Ni alloy composite strengthening materials have been investigated by means of scanning electron microscopy (SEM), electron dispersion X-ray analysis (EDAX) and wear test. Effect of applied load and sliding distance on the wear behavior of the strengthening materials are also studied in this paper. The results show...
This research was inspired by increasing interest in ecological lubricants. Aqueous solutions of alkyl polyglucosides (APGs) were chosen as potential lubricant compositions. Commercially provided products were tested for surface tension, wetting angle, light diffusion and viscosity. Additionally, atomic force microscopy, polarized light microscopy and X-ray spectroscopy were employed. The tests were...
Epoxy resin composites are frequently applied in moulds manufactured with rapid tooling technologies that are used for wax and polymer materials injection. With the propose of enlarging the application field of the polymer matrix systems, it is fundamental to select adequate dispersed phases and analyse their influence on the composite properties in order to reinforce the polymer matrix and tailor...
Dry-sliding and lubricated friction and wear behaviours of polyamide (PA) and ultra-high molecular weight polyethylene (UHMWPE) blend were studied using a pin-on-disc method (polymer pin sliding against a stainless steel disc) at room environment. The tribological performance of PA and UHMWPE were also investigated for the purpose of comparison. The worn surfaces were examined using a scanning electron...
Microplasma oxidation (MPO) has recently been studied as a cost-effective plasma electrolytic process to provide thick and hard ceramic coatings with excellent surface load-bearing capacity on aluminum alloys. However, for sliding wear applications, such ceramic coatings often exhibit relatively high friction coefficients against many counterface materials. Although coatings deposited by physical...
In this work, the most commonly used joint materials for substitution of hip joints, ultra high molecular weight polyethylene (UHMWPE) for the cup, and alumina, stainless steel or CoCrMo alloy for the head, were submitted to pin-on-disk tribological tests. The interfacial behaviour prosthetic material/lubricant was investigated through wettability measurements. Four lubricants were used: Hanks’ balanced...
In the present work, an attempt has been made to improve the surface hardness and wear properties of magnesium alloys AZ31 and AZ61 through solid solution hardening and refinement of microstructures using a 1.5kW high power diode laser (HPDL) as a heat generating source. One millimetre thick uniform overlapping melt tracks were produced on Mg alloy samples. Laser-melted samples were subjected to a...
In this paper, lateral force microscope (LFM) is used to investigate the frictional behavior of GeSb 2 Te 4 film of 20nm thickness deposited by magnetron sputtering. The effect of relative humidity, scanning rate, scanning area on friction is concerned. The JKRS (Johnson–Kendall–Roberts) theory considering the energy of adhesion between tip and GeSb 2 Te 4 (at.%) film...
The increasing use of small micromechanical devices and advanced sensors has led to concern about the failure modes and reliability of these structures. The enormous promise will not materialize without substantial progress in overcoming the stiction, friction and wear associated with such devices and understanding the mechanical behavior of MEMS materials and structures. Self-assembled monolayers...
In the present work, we report the processing and properties of WC–6wt.% ZrO 2 composites, densified using the pressureless sintering route. The densification of the WC–ZrO 2 composites was carried out in the temperature range of 1500–1700°C with varying time (1–3h) in vacuum. The experimental results indicate that significantly high hardness of 22–23GPa and moderate fracture toughness...
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