• 제목/요약/키워드: Friction characteristics

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자동차 브레이크용 마찰재 내의 강철섬유, 지르콘, 캐슈가 크립 그론에 미치는 영향 (Effects of Steel Fiber, Zircon, and Cashew in the Brake Friction Materials on Creep Groan Phenomena)

  • 장호;이강선;이은주;정근중;송현우
    • Tribology and Lubricants
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    • 제23권6호
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    • pp.278-282
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    • 2007
  • Friction characteristics of a low-steel friction material were examined to investigate creep groan phenomena. The amount of three ingredients (steel fiber, $ZrSiO_4$, cashew) were changed to produce test specimens using a constrained mixture design. Tribological properties of the friction material specimens were obtained by using a 1/5 scale dynamometer. Results showed that the amount of three different ingredients strongly affected the level of friction coefficient and the difference between the static friction coefficient and the kinetic friction coefficient $({\Delta}{\mu}).\;ZrSiO_4$ and steel fiber tended to increase the average friction coefficient and aggravated the stick-slip phenomena suggesting high creep groan propensity. On the other hand, cashew tended to decrease average friction coefficient and ${\Delta}{\mu}$.

패드식 피스톤의 특성 해석에 관한 연구 (Analysis of the Characteristics of the Low Friction Pad Type Piston)

  • 김청균;김희붕
    • Tribology and Lubricants
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    • 제9권2호
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    • pp.70-78
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    • 1993
  • Using the finite element method, the film pressure, the transverse force and the firction torque which are distributed over the pad surface of low-friction piston skirt are calculated in order to investigate the dynamic characteristics of the piston. The results indicate that the frictional torque for the low-friction piston pad may increase 3% efficiency in comparison th the conventional one.

DLC와 PTFE표면코팅에 따른 자기유변유체의 마찰 마모 특성 (Friction and Wear Characteristics of Magneto-rheological Fluid Depend on Surface Coated by DLC and PTFE)

  • 장붕;이광희;이철희;최종명
    • Tribology and Lubricants
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    • 제31권2호
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    • pp.62-68
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    • 2015
  • A magnetorheological (MR) fluid is a smart material whose rheological behavior can be controlled by varying the parameters of the applied magnetic field. Because the damping force and shear force of an MR fluid can be controlled using a magnetic field, it is widely employed in many industrial applications, such as in vehicle vibration control, powertrains, high-precision grinding processes, valves, and seals. However, the characteristics of friction caused by iron particles inside the MR fluid need to be understood and improved so that it can be used in practical applications. Surface process technologies such as polytetrafluoroethylene (PTFE) coatings and diamond-like carbon (DLC) coatings are widely used to improve the surface friction properties. This study examines the friction characteristics of an MR fluid with different surface process technologies such as PTFE coatings and DLC coatings, by using a reciprocating friction tester. The coefficients of friction are in the following descending order: MR fluid without any coating, MR fluid with a DLC coating, and MR fluid with a PTFE coating. Scanning electron microscopy is used to observe the worn surfaces before and after the experiment. In addition, energy dispersive X-ray spectroscopy is used to analyze the chemical composition of the worn surface. Through a comparison of the results, the friction characteristics of the MR fluid based on the different coating technologies are analyzed.

고탄소크롬 베어링강 2종(SUJ2) 베어링강에 증착된 저마찰 코팅의 트라이볼로지적 특성 연구 (A Study on the Tribological Characteristics of Low Friction Coating Deposited on SUJ2 Bearing Steel)

  • 강경모;신동갑;박영훈;김세웅;김대은
    • Tribology and Lubricants
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    • 제34권6호
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    • pp.254-261
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    • 2018
  • In order to reduce resistance torque and energy loss, minimizing friction between race surface and rolling elements of a bearing is necessary. Recently, to reduce friction in bearing element, solid lubricant coating for the bearing raceway surface has been receiving much attention. Considering the operating conditions of real bearings, verifying the effect of solid lubricant coatings under extreme conditions of high load that is more than 1 GPa is necessary. In this study, we evaluated the friction and wear characteristics of SUJ2 bearing steels deposited by carbon-based coatings (Si-DLC, ta-C), $MoS_2$ and graphite. In case of $MoS_2$ and graphite coatings, different surface treatments were applied to the coatings to verify the effect of surface treatment. A pin-on-disc type tribotester was used to evaluate the tribological characteristics of the coatings. It was possible to quantitatively estimate the friction and wear characteristics of solid lubricant under dry and lubrication conditions. The carbon-based coatings improved the friction and wear properties of SUJ2 bearing steels under the high load condition, but $MoS_2$ and graphite coatings were not suitable for high load conditions due to its low hardness. Different friction and wear behaviors were found for different substrate surface treatment method. Also, it was confirmed that solid lubricant coatings had a more positive effect than just applying the lubricant for improving the tribological characteristics.

외부 공기속도 변화에 따른 소결마찰재와 디스크간 마찰특성 (Influence of External Air Velocity for Tribological Characteristics between Sintered Friction Material and Disk)

  • 김영규;김상호;권석진;정수영;이희성
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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    • pp.975-985
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    • 2011
  • Cu-Matrix sintered brake pads and low alloyed heat resistance steel are most applied to basic brake system for high energy moving machine. In this research, we analyzed tribological characteristics for influence of air velocity between disk and pad. At low brake pressure with air flow, friction stability was decreased due to no formation of tribofilm at disk surface. But there are no significant change of friction coefficient at all test conditions. Wear rate of friction materials were decreased with increasing of air flow velocity. In result, air flow velocity influenced friction stability, wear rate of friction materials and disk but not friction coefficient.

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CFRP 복합재의 적층방향에 대한 마찰 및 마모 특성 (Friction and Wear Characteristics of Carbon Fiber Reinforced Composites against Lay-up Orientation)

  • 고성위;최영근
    • 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.

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$ZrSiO_4$가 첨가된 마찰재의 마찰 안정성 (Friction Stability of Materials with $ZrSiO_4$ Addition)

  • 이동규;박상찬
    • 한국안전학회지
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    • 제14권3호
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    • pp.110-119
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    • 1999
  • This study was conducted to invent brake of non-steel material without using asbestos and disc pad added $ZrSiO_4$ was made. The physical properties and friction characteristics were investigated by varying methods. The physical properties were inspected of shear strength, hardness, heat expansion, specific gravity, % of gashole, thickness variation, weight variation and pH variation. The friction stability was measured by friction coefficient on variations of speed, temperature and deceleration condition. It was found that the physical properties were in general excellent. According to the friction characteristics tests, $ZrSiO_4$ had an abrasive property. As a results, the friction materials containing $ZrSiO_4$ 3~5vol% showed better resistance to fading and improved friction stability than the materials without ZrSiO$_4$.

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이온도움반응법에 의한 탄소섬유복합재의 트라이볼로지 특성연구 (Tribological Characteristics of Carbon Fiber Reinforced Plastics Prepared by Ion-Assisted Reaction)

  • 오성모;김정기;이봉구
    • 한국정밀공학회지
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    • 제21권4호
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    • pp.103-108
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    • 2004
  • Carbon fiber reinforced composites(CFRP) were fabricated with phenolic resin matrix by hot press molding, and its surface was modified by the ion-assisted reaction process. When we tested the friction coefficient and wear rate variation and observed the effect of fibers with respect to friction and wear characteristics, the amount of pitch based carbon fiber was 45wt% and the average friction coefficient was the lowest at 0.12. When the amount of ion-irradiation was $1\times10^{l6}ions/cm^2$, the friction coefficient of the composites was about 0.12 and the wear mode was stable, whereas, the friction coefficient of the non-treated composites was about 0.16 and the wear mode was very unstable. But if the amount of ion-irradiation was $5\times10^{l6}ions/cm^2$$1\times10^{l6}ions/cm^2$ion-irradiation case.

왕복운동에서의 고유주파수 변화에 따른 마찰소음 특성 연구 (Characteristics of Friction Noise with Changes of the Natural Frequencies in the Reciprocating Motion)

  • 최호일;강재영
    • 한국소음진동공학회논문집
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    • 제24권4호
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    • pp.332-338
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    • 2014
  • Experimental study is conducted for investigating the characteristics of friction-induced noise with respect to the variation of system geometry. In this study, a vertically fixed rod is in contact with the reciprocating plate which is controlled by the step motor. Friction noise is generated during the reciprocating motion due to the frictional contact between the plastic pin and the aluminum plate. The frequencies of the friction noise are changed when the height of the rod varies. However, it is found that the vibration modes involved in the friction noise are not changed. It implies that the unstable modes remain unstable regardless of the change of the system geometry, and thus, there are the certain mode shapes which are likely to produce friction noise.

크레인 선회감속기의 습식 다판 브레이크를 위한 카본 페이퍼 마찰 디스크의 제동 특성 (Braking Characteristics of Friction Disk made of Carbon Paper for Wet-type Multiple Disk Brakes of Crane Turning Decelerator)

  • 조연상;배명호
    • Tribology and Lubricants
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    • 제28권3호
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    • pp.112-116
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    • 2012
  • wet-type multiple disk brakes are very important parts of turning decelerator for deck crane, because they are advanced in durability and braking power, and can be designed compactly. Thus, we designed and made wet-type multiple disk brakes of turning decelerator for deck crane to be localization of these imported all. In this study, wet multiple disk brakes were made a comparative test with the 2 types materials of friction disk by the SAE No.2 dynamometer. The friction characteristics were measured and analyzed to decide a suitable material as wear depth of friction disk and dynamic and static friction coefficient.