Current Issue : October - December Volume : 2017 Issue Number : 4 Articles : 5 Articles
An important parameter in the reduction of fuel consumption of heavy-duty diesel engines is the Power Cylinder Unit (PCU); the\nPCU is the single largest contributor to engine frictional losses.Much attention, fromboth academia and industry, has been paid to\nreducing the frictional losses of the PCU in the boundary and mixed lubrication regime.However, previous studies have shown that\na large portion of frictional losses in the PCU occur in the hydrodynamic lubrication regime. A novel texturing design with large\ntypes of surface features was experimentally analyzed using a tribometer setup.Theexperimental result shows a significant reduction\nof friction loss for the textured surfaces. Additionally, the textured surface did not exhibit wear. On the contrary, it was shown that\nthe textured surfaces exhibited a smaller amount of abrasive scratches on the plateaus (compared to the reference plateau honed\nsurface) due to entrapment of wear particles within the textures. The decrease in hydrodynamic friction for the textured surfaces\nrelates to the relative increase of oil film thickness within the textures. A tentative example is given which describes a method of\ndecreasing hydrodynamic frictional losses in the full-scale application....
Polyamide (PA6/6) is often used as a tribological pair in abrasion prevalent applications such as hinges and sliders. PA6/6 is\nfrequently processed by injection moulding and extrusion process. It is known that these processes influence the polymers\nmechanical behaviour, but their influence on the polymers wear response has not been studied.Hence the present research attempts\nto study the influence of differentmanufacturing processes on tribological behaviour for PA6/6.Wear tests were performed on a pin\nabrading tester (DIN 50322). Abrasion resistance of both extruded and injection moulded PA6/6 were tested at different loads (20\nand 35N). Single-pass (nonoverlapping mode) and multipass testing (overlapping mode) were used to understand the influence of\nclogging of wear debris. It is evidenced that with increasing load the specific wear rate decreases; moreover, fine abrasives tend to\nreduce the wear rate. Inmultipass testing a transfer layer clogged on the counterface that acted as a protective agent and lowers wear\nrate. Poor mechanical strength of injection moulded polymers is apparently compensated by microstructural response for having\na similar wear behaviour between extruded and injection moulded PA 6/6. Hence a proper balance between microstructural and\nmechanical characteristics is an absolute must in PA 6/6 for better wear performance....
With the increasing pressure to reduce emissions, friction reduction is always an up-to-date\ntopic in the automotive industry. Among the various possibilities to reduce mechanical friction,\nthe usage of a low-viscosity lubricant in the engine is one of the most effective and most economic\noptions. Therefore, lubricants of continuously lower viscosity are being developed and offered on\nthe market that promise to reduce engine friction while avoiding deleterious mixed lubrication and\nwear. In this work, a 1.6 L downsized Diesel engine is used on a highly accurate engine friction\ntest-rig to determine the potential for friction reduction using low viscosity lubricants under realistic\noperating conditions including high engine loads. In particular, two hydrocarbon-based lubricants,\n0W30 and 0W20, are investigated as well as a novel experimental lubricant, which is based on a\npolyalkylene glycol base stock. Total engine friction is measured for all three lubricants, which\nshow a general 5% advantage for the 0W20 in comparison to the 0W30 lubricant. The polyalkylene\nglycol-based lubricant, however, shows strongly reduced friction losses, which are about 25% smaller\nthan for the 0W20 lubricant. As the 0W20 and the polyalkylene glycol-based lubricant have the same\nHTHS-viscosity , the findings contradict the common understanding that the HTHS-viscosity is the\ndominant driver related to the friction losses....
Due to the low density and high temperature resistance, the SiCp/A356 composites have great potential for weight reduction and\nbraking performance using the brake disc used in trains and automobiles. But the friction coefficient and braking performance\nare not stable in the braking process because of temperature rising. In this paper, friction and wear behaviors of SiCp/A356\ncomposite against semimetallic materials were investigated in a ring-on-disc configuration in the temperature range of 30âË?Ë?C to\n300âË?Ë?C. Experiments were conducted at a constant sliding speed of 1.4 m/s and an applied load of 200N.Worn surface, subsurface,\nand wear debris were also examined by using SEM and EDS techniques. The third body films (TBFs) lubricated wear transferred\nto the third body abrasive wear above 200âË?Ë?C, which was a transition temperature.The friction coefficient decreased and weight of\nsemimetallic materials increased with the increase of temperature and the temperature had almost no effect on the weight loss of\ncomposites. The dominant wear mechanism of the composites was microploughing and slight adhesion below 200âË?Ë?C, while being\ncontrolled by cutting grooves, severe adhesion, and delamination above the 200âË?Ë?C....
In order to improve the tribological properties of an engine piston ring and enhance\nits service life, magnetron sputtering technology and low temperature ion sulphurizing treatment\ntechnology were used to prepare CrMoN/MoS2 solid lubricant coating on the surface of an engine\npiston ring. The morphologies and compositions of the surface and cross-section of the sulfuration\nlayer were analyzed by field emission scanning electron microscopy (FESEM), and wear property\nunder high load, high speed and high temperature conditions were tested by a SRV�®4 friction and\nwear testing machine. The results show that the CrMoN/MoS2 composite coatings appear as a dense\ngrain structure, and the coating is an ideal solid lubrication layer that possesses an excellent high\ntemperature wear resistance, reducing the engine operating temperature abrasion effectively and\nprolonging the service life of the engine....
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