• Tribology and Lubricants
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• 제9권1호
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• pp.62-69
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• 1993

Friction and wear behavior of a carbon/carbon composite material for aircraft brake material was experimentally investigated. Friction and wear test setup was designed and built for the experiment. Friction and wear tests were conducted under various sliding conditions. Friction coefficients were measured and processed by a data acquisition system and amount of wear measured by a balance. Stainless steel disk was used as the counterface material. Temperature was also measured by inserting thermocouple 2.5 mm beneath the sliding surface of the carbon/carbon composite specimen. Wear surfaces were observed by SEM, and analyzed by EDAX. The experimental results showed that sliding speed and normal force did not have significant effects on friction coefficient and wear factor of the composite. Temperature increase just below the surface was not large enough to cause any thermal degradation or oxidation which occurred at higher temperature when tested by TGA. Wear film was generated both on the specimen and on the counterface at relatively low sliding speed but cracks, grooves, and wear debris were observed at high sliding speed. Friction coefficient remained almost constant when the sliding speed or normal load was varied. It is believed that the adhesive and abrasive components contributed mainly to the friction coefficient. Wear behavior at low sliding speed was governed by wear film formation and adhesive wear mechanism. At high speed, fiber orientation, ploughing by counterface asperities, and fiber breakage dominated wear of the carbon/carbon composite.

• 동력기계공학회지
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• 제9권2호
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• pp.57-64
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• 2005

This paper is the study on dry sliding wear behavior of carbon fiber reinforced epoxy matrix composites against lay-up orientation. Tests were investigated on the effect of the lay-up orientation, fiber sliding direction, load and sliding velocity when circumstance keep continuously at $21^{\circ}C$, 60%RH. Pin-on-disk dry sliding wear tests for each experimental condition were carried out with a carbon fiber reinforced plastic pin on stainless steel disk in order to search the friction and wear characteristics. The wear rates and friction coefficients against the stainless steel counterpart were experimentally determined and the wear mechanisms were microscopically observed. The effect on friction and wear behavior are observed differently, according to various conditions. When sliding took place against counterpart, the highest wear resistance and the lowest friction coefficient were observed in the $[0]_{24s}$ lay-up orientation at anti-parallel direction.

• 열처리공학회지
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• 제11권3호
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• pp.159-167
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• 1998

In this study, friction-wear test was carried out on the carburized layer depth of a mechanical structure steel SNCM carburized with RX and LPG for 7hrs at $930^{\circ}C$ and also the wear properties of wear loss, wear rate, coefficient of friction, friction force and friction temperature were investigated. The wear properties for carburized layer of SNCM were tested on dry condition at the room temperature by the thrust load of 49~245N range at sliding speed of 0.2m/sec and the sliding speed of 0.2~1.0m/sec range at thrust load of 98N. Wear loss on the depth of carburizing layer was increased with increasing of thrust load and sliding speed, and with decreasing of hardness. The condition of worn surfaces were showed mild wear at less than the thrust load of 98N and sliding speed of 0.6m/sec but were showed severe wear at more than 98N and 0.6m/sec. The friction load and temperature were increased with increasing of thrust load but with increasing sliding speed was appeared minimum at 0.6m/sec. With increasing thrust load the wear rate was increased and the coefficient of friction was decreased, but with increasing sliding speed the wear rate and the coefficient of friction were decreased in 0.2~0.6m/sec and increased in 0.6~1.0m/sec, therefore 0.6m/sec in this testing is a transition velocity.

• Tribology and Lubricants
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• 제16권1호
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• pp.1-8
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• 2000

Friction and wear tests have been performed on nylon, acetal resin, and PTFE (polytetrafluoroethylene), in reciprocating dry sliding conditions against steel discs. According to the results, acetal resin showed the lowest wear rates and PTFE exhibited the lowest friction coefficient. The prominent wear mechanisms found were adhesion and abrasion.

• Tribology and Lubricants
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• 제10권3호
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• pp.29-38
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• 1994

The friction and wear of mild steel at dry sliding surfaces under different vacuum conditions have been investigated to understand the wear mechanisms. For the test, a ball-ondisk typed wear-rig has been built and implemented, allowing control of sliding speed, load and vacuum. Results show that, at a high sliding velocity, friction of low carbon steel (SS41) under a high vacuum is much higher than that of ambient condition and wear is much severer. It is due to lack of effective oxidation film formation on which steel surfaces could protect themselves against the severe wear. It has been shown, however, that there is a critical regime with contact conditions (at a low sliding velocity, a low load, and under a medium vacuum) at which effective, protective films of low carbon steel have been built on the surfaces in a friction process with a self-regulating way, resulting in both very low coefficients of friction (about 0.3) and mild wear. In order to investigate the protective films on steel surfaces, the worn surfaces and the wear debris have been experimentally analyzed with SEM, AES/SAM and XRD. A theoretical analysis of frictional heating at sliding surfaces, and an experimental analysis of the influence of oxidation wear under various vacuum conditions are described. The important variables on which self-formations of protective films at dry sliding surfaces depend, and the wear mechanisms are also investigated.

• Tribology and Lubricants
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• 제10권4호
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• pp.13-26
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• 1994

Effects of resin contents, number of carbonization, graphitization, sliding speed, and oxidation on friction and wear behavior of carbon/carbon composite materials were investigated. Friction and wear tests were carried out under various sliding conditions. An experimental setup was designed and built in the laboratory. Stainless steel disks were used as the counterface material. Friction coefficient, emperature, and wear factor were measured with a data acquisition system. Wear surfaces were observed by the scanning electron microscope. It has been shown that the average friction coefficient was increased with the sliding speed in the range of 1.43~6.10 m/s, but it as decreased in the range of 6.10~17.35 m/s. Specimens prepared by different numbers of carbonization. showed variations in friction coefficient and friction coefficient of the graphitized specimen was the highest. Friction coefficients depended on contribution of the plowing and adhesive components. As the number of carbonization was increased, wear factor was reduced. Wear factor of the graphitized specimens dropped further. In the case of graphitized specimens, sliding speed had a large influence on wear behavior. When the tribological experiments were conducted in nitrogen atmosphere, the wear factor was decreased to two thirds of the wear factor obtained in air. It is obvious that the difference was affected by oxidation. Results of friction and wear tests were applied to a neural network system based on the backpropagation algorithm. A neural network may be a valuable tool for prediction of tribological behavior of the carbon/carbon composite material if ample data are present.

• 수산해양기술연구
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• 제44권3호
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• pp.250-256
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• 2008

Generally the side plate materials of FRP ship are composed of glass fiber and unsaturated polyester resin composites(GFRP composites). In this study, the effect of applied load and sliding speed on friction and wear characteristics of these materials were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials for SiC abrasive paper were determined experimentally. The cumulative wear volume showed a tendency to increase nonlinearly with increase of sliding distance and was dependent on applied load and sliding speed for these composites. The friction coefficient of GFRP composites was increased as applied load increased at same sliding speed in wear test. It was verified by SEM photograph of worn surface that major failure mechanisms were microfracture, deformation of resin, cutting and cracking.

• Tribology and Lubricants
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• 제24권2호
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• pp.96-103
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• 2008

PTFE is generally utilized as the form of composites with adding various fillers. The purpose of this paper lies on clarifying the friction and wear properties of the PTFE coating layer on steel. Especially, the effects of PTFE powder size for coating and surface roughness of the counter material on the properties are investigated. Sliding friction and wear tests are conducted at several sliding speeds by employing two types of PTFE coating layer using different powder sizes. One type of coating layer is composed of uniform fine powder, whereas the other type is made up of mixture powder of different sizes. As results, it is found that PTFE coating layer are effective to improve the wear resistance and to reduce the friction coefficient. It is clear that PTFE coating layers are abrasively removed by asperities of the counter material during sliding contact. However, PTFE coating layer with uniform fine powder shows somewhat better wear resistance than that with mixture powder of different sizes in low sliding speed region. It can be seen that the wear of the coating layer are drastically reduced because wear fragment from counter material are transferred to the coating layer. On the other hand, friction coefficient is shown not to be directly related with PTFE powder size in coating layer.

• 수산해양기술연구
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• 제48권3호
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• pp.277-283
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• 2012

The characteristics of abrasive wear on sliding speed of glass fiber reinforcement (GF/PUR) composites were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and surface roughness of these materials on sliding speed were determined experimentally. The major failure mechanisms were lapping layers, deformation of resin, ploughing, delamination, and cracking by scanning electric microscopy (SEM) photograph of the tested surface. As increasing the sliding speed the GF/PUR composites indicated higher friction coefficient. The surface roughness of the GF/PUR composites was increased as the sliding speed was higher in wear test.

• Tribology and Lubricants
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• 제8권2호
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• pp.20-25
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• 1992

Friction and wear behavior of hot isostatic pressed $Al_2O_3-TiC$ was experimentally examined. Pin-on-disk type friction and wear apparatus was designed and manufactured for the experiment. The experiments were conducted under unlubricated sliding motion in both low and high humidity for three kinds of sliding speed. $Al_2O_3-TiC$ and bearing steel were used as counterface materials. Friction coefficient, wear rate, and surface roughness were measured. Wear surface and wear debris were observed through optical microscope and SEM and analyzed by EDAX. The results showed that the counterface materials, the sliding speed, and the moisture at the sliding surface have significant influence on the friction coefficient and wear rate of $Al_2O_3-TiC$.