Papers by Mubashir Gulzar
– In the present study, the effect of indirect laser texturing on the tribological performance of... more – In the present study, the effect of indirect laser texturing on the tribological performance of diamond like carbon coatings has been investigated. Micro dimples were created before DLC coating was deposited. Dimple diameters were changed while keeping density and depth constant, in order to study the effect of change in dimension on the coating performance. The results indicate that optimum surface texturing parameters reduces the friction and wear at the contact. Dimple diameter of 100 µm increased the wear resistance of DLC by lowering the wear particle induced graphitization.
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– Improvement in the anti-wear (AW) and extreme pressure (EP) ability of chemically modified jatr... more – Improvement in the anti-wear (AW) and extreme pressure (EP) ability of chemically modified jatropha oil (CMJO) by adding nanoparticles was experimentally evaluated. Nano-lubricants were synthesized by adding 1 wt% tungsten disulfide (WS2) nanoparticles to CMJO. The AW/EP ability of trial oils were evaluated using four-ball wear tests. Wear surfaces were analyzed by scanning electron microscopy (SEM) along with energy-dispersive X-ray (EDX). The addition of 1 wt% oleic acid as surfactant (S) assisted in reducing the agglomerates. The addition of WS2 nanoparticles improved AW/EP properties of CMJO.
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Tribological efficiency of industrial applications involving boundary lubrication regime can be i... more Tribological efficiency of industrial applications involving boundary lubrication regime can be improved to an appreciable extent by the deposition of hard coatings on interacting surfaces. Among such coatings, diamond-like carbon (DLC) coatings are considered to be one of the most suitable ones for the said role. DLC coatings possess a unique combination of physical, chemical, and material properties due to which they can help in minimizing friction-induced energy and material losses even under starved lubrication conditions. Since commercial lubricants are optimized for steel surfaces, therefore, a lot of experimental investigations were carried out to analyze the tribological compatibility of these lubricants with various DLC coatings. However, there is still a lack of understanding about how DLC coatings interact with conventional lubricant additives. Some researchers reported tribologically beneficial interactions between DLC coatings and formulated lubricants while others observed no such behavior. To address these inconsistencies, there is a need to rearrange the published data in a more apprehensible and organized manner with a special emphasis on the mechanisms responsible for a particular tribological behavior. In this way, it can be determined whether synergistic or antagonistic correlation exists between a particular DLC-lubricant combination and research on DLC coatings can be continued in a logical way. In this article, most widely investigated non-doped DLC coatings (ta-C, a-C:H, a-C, and ta-C:H) are tribologically analyzed. Average values of friction and wear coefficients are calculated for various DLC-lubricant combinations using already published data and compared to quantify the effectiveness of a particular lubricant additive in enhancing tribological characteristics of symmetrical non-doped DLC contacts. Moreover, tribological performance parameters of non-doped DLC coatings are compared with those of doped-DLC coatings to understand differences in their tribological behavior in combination with additives.
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Fuel is considered a major influencing parameter for engine oil condition during extended engine ... more Fuel is considered a major influencing parameter for engine oil condition during extended engine operation. Its effects on engine oil performance is required to be investigated with the implementation of the worldwide biodiesel mandate in various countries. This research monitored the influence of biodiesel on the condition of engine lube oil by long duration testing on three fuels: DF as the baseline; 20% palm biodiesel and 80% DF (PB20); and 20% jatropha biodiesel and 80% DF (JB20). The tests were carried out on a single-cylinder CI engine. Sump oil samples were collected at regular intervals during 200-h tests, after which the rheological, tribological, and chemical properties of the samples were investigated. Results showed that the B20 fuels decreased the viscosity and increased the acidity of the engine oil. Piston ring-cylinder and piston skirt-cylinder tests, in which a high-stroke reciprocating test rig was used, showed a slight increase in friction and wear losses near the intervals of oil draining for the B20 fuels. Chemical analysis by Fourier transform infrared spectroscopy and ASTM standard testing showed a decrease in soot loading but an increase in the fuel residue, corrosiveness, and oxidation of the engine oil samples for B20 fuelled engine tests.
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Journal of Materials Research, 2016
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Crack formation in polyurethane material is an exceedingly non-linear and complex phenomenon. A 2... more Crack formation in polyurethane material is an exceedingly non-linear and complex phenomenon. A 2-D plain strain, linear and non-linear analysis to understand the influence of central cracks and crack sizing is discussed under Mode 1 of crack displacement i.e. Opening Mode. Cracks in solid rocket propellant disturb the geometry and require design characteristics .This research work deals with investigation of stress intensity factor determined experimentally and Finite Element based simulations, which can be used to help explain the severity of the associated crack in a given material. This investigation involves single polyurethane material sheets which have Photo elastic characteristics. The global geometry used for this purpose is rectangular. The stress intensity factors were examined and a comparison between linear and non-linear analysis of crack propagation is presented for central crack propagation in the opening mode. The result shows stress intensity factor for a range of ...
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The absence of fully developed fluid film lubrication between Piston and Liner surfaces is respon... more The absence of fully developed fluid film lubrication between Piston and Liner surfaces is responsible for high friction and wear at initial engine start-up. In this paper flow factor method is used in two dimensional Reynolds' equation to model the effects of surface roughness characteristics on Piston Skirt elastohydrodynamic lubrication. The contact of surface asperities between the two surfaces and its after effects on EHL of piston skirt is investigated. For this purpose, two different grade oils are used to show the changing effects of viscosity combined with surface roughness on different parameters including film thickness, eccentricities and hydrodynamic pressures. The results of the presented model shows considerable effects on film thickness of rough piston skirt, hydrodynamic pressures and eccentricities profiles for 720 degrees crank angle.
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Tribology in Industry
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An effective lubrication of the rough surfaces of the piston skirts and the cylinder liner is req... more An effective lubrication of the rough surfaces of the piston skirts and the cylinder liner is required to eliminate adhesive wear and minimize the power dissipation in the initial engine start-up. The effects of the surface roughness of the piston skirts become evident when the magnitude of the film thickness of the lubricant is comparable with the height of the asperities. In this work a 2-D numerical piston skirts hydrodynamic and elastohydrodynamic lubrication (EHL) model is developed by considering the stochastic rough surfaces with deterministic asperities. An Average Flow Factor Method is used to model the rough surfaces in order to investigate the effects of surface roughness on the performance parameters involving the lubrication of the piston skirts. The random rough surfaces of the skirts and the liner with varying Peklenik number are generated for the EHL model. The simulation results show that the pressure and the shear flow factors affect the hydrodynamic friction, the ...
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Texture improve tribological behavior of oil lubricated amorphous hydrogenated DLCWear coefficien... more Texture improve tribological behavior of oil lubricated amorphous hydrogenated DLCWear coefficient reduced up to 89.7% for textured amorphous hydrogenated DLCWear induced graphitization lowered for textured amorphous hydrogenated DLCHardness deterioration by graphitization reduced for textured hydrogenated DLCDeep dimples are detrimental in boundary/starved regime for non-conformal contactIn this study, the effect of surface texturing parameters on the tribological performance of amorphous hydrogenated diamond-like carbon (DLC) under oil lubrication has been investigated. Micro dimples were created on a substrate by using a picosecond laser. After surface texturing was performed, amorphous hydrogenated diamond-like carbon (DLC) coating was deposited through magnetron sputtering. Dimple diameter varied from 50 μm to 300 μm, and dimple depth varied from 6 μm to 30 μm. Results show that at respective dimple diameter and depth of 100 and 6 μm, surface texturing improved the tribological performance of the amorphous hydrogenated DLC coating. Whereas, at a higher dimple diameter of 300 μm and dimple depth of 30 μm, the tribological performance of textured amorphous hydrogenated DLC was worse than that of un-textured amorphous hydrogenated DLC. The performance enhancement in the case of dimple diameter and depth of 100 μm and 6 μm can be due to micro textures, which can serve as a lubricant reservoir at the interface during sliding and remove wear particles from the contact. However, this beneficial mechanism could be obtained at an optimum texture diameter and depth.
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The purpose of this research is experimental study of Calophyllum inophyllum (CI) based Trymethyl... more The purpose of this research is experimental study of Calophyllum inophyllum (CI) based Trymethylolpropane (TMP) ester as energy saving and biodegradable lubricant and compare with commercial lubricant and paraffin mineral oil by using four ball tribometer. CI based TMP ester is a renewable lubricant that is non-edible, biodegradable, non-toxic and has a net zero greenhouse gases. The TMP ester was produced from CI oil, which has high lubricity properties such as higher density, higher viscosity at both 40°c and 100°c and higher viscosity index (VI). Experiment was conducted during 3600s with constant load of 40 kg and constant sliding speed of 1200 rpm at temperature of 50°C, 60°C, 70°C, 80°C, 90°C and 100°C for both three types of lubricant. The results show that CI TMP ester had the lowest coefficient of friction (COF) as well as lower consumption of energy at all test temperature, but the worn surface roughness average (Ra) and wear scar diameter were higher compared to paraffin mineral oil and commercial lubricant. Before 80°C, CI TMP ester actually has higher flash temperature parameter (FTP) than paraffin mineral oil and as the temperature increases, the FTP of TMP ester decreases. The worn surfaces of the stationary balls were analyzed by SEM and results show that CI TMP ester have the highest wear compared to paraffin mineral oil and lowest wear compared to commercial lubricant. However, CI TMP ester is environmentally desired, competitive to commercial lubricant and should be encouraged.Accepted Author Version. Not yet edited or proofed. Please see disclaimer on the article abstract page.
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Papers by Mubashir Gulzar