• Title, Summary, Keyword: Sliding wear

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Friction and Wear Behavior of Carbon/Carbon Composites for Aircraft Brake Material (항공기 브레이크 재료용 탄소/탄소 복합재료의 마찰 및 마모 거동)

  • 우성택;윤재륜
    • Tribology and Lubricants
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    • v.9 no.1
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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.

Wear Characteristics of Particulate Reinforced Metal Matrix Composites Fabricated by Pressureless Metal Infiltration Process (무가압함침법으로 제조된 입자강화 금속복합재료의 마모특성)

  • Kim, Jae-Dong;Jung, Sun-Uk;Kim, Hyung-Jin
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.379-384
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    • 2002
  • The effect of size and volume fraction of ceramic particles with sliding velocity on the wear properties were investigated for the metal matrix composites fabricated by pressureless infiltration process. The particulate metal matrix composites exhibited about 5.5 - 6 times of excellent wear resistance compared with AC8A alloy at high sliding velocity, and as increasing the particle size and decreasing the volume fraction the wear resistance was improved. The wear resistance of metal matrix composites and AC8A alloy exhibited different aspects. Wear loss of AC8A alloy increased with sliding velocity linearly. whereas metal matrix composites indicated more wear loss than AC8A alloy at slow velocity region, however a transition point of wear loss was found at middle velocity region which show the minimum wear loss, and wear loss at high velocity region exhibited nearly same value with slow velocity region. In terms of wear mechanism, the metal matrix composites exhibited the abrasive wear at slow to high sliding velocity generally, however AC8A alloy showed abrasive wear at low sliding velocity and adhesive and melt wear at high sliding velocity.

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Wear Characteristics of Particulate Reinforced Metal Matrix Composites Fabricated by a Pressureless Metal Infiltration Process (무가압함침법으로 제조된 입자강화 금속복합재료의 마모특성)

  • 김재동;정순억;김형진
    • Journal of Ocean Engineering and Technology
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    • v.17 no.1
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    • pp.55-60
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    • 2003
  • The effect of size and volume fraction of ceramic particles, with sliding velocity on the wear properties were investigated for the metal matrix composites fabricated by the pressureless infiltration process. The metal matrix composites exhibited about 5.5 - 6 times the wear resistance compared with AC8A alloy at high sliding velocity, and by increasing the particle size and decreasing the volume fraction, the wear resistance was improved. The wear resistance of metal matrix composites and AC8A alloy exhibited different aspects. Wear loss of AC8A alloy increased with sliding velocity, linearly : whereas, metal matrix composites indicated more wear loss than AC8A alloy at the slow velocity region. However, a transition point of wear loss was found at the middle velocity region, which shows the minimum wear loss. Further, wear loss at the high velocity region exhibited nearly the same value as the slow velocity region. In terms of wear mechanism, the metal matrix composites generally exhibited abrasive wear at slow to high sliding velocity; however, AC8A alloy showed abrasive wear at low sliding velocity and adhesive and melt wear at high sliding velocity.

Effects of thickness and applied load on wear mechanisms of PMMA (Poly Methyl Methacrylate) coating layers (PMMA(Poly Methyl Methacrylate) 코팅층 두께 및 적용하중에 따른 마멸기구 분석)

  • Kang S. H.;Kim Y. S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.152-155
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    • 2004
  • Effects of sliding speed, applied load, counterpart radius and thickness of PMMA (Poly Methyl Methacrylate) coating layers on their dry sliding frictional and wear behavior were investigated. Sliding wear tests were carried out using a pin-on-disk wear tester. The PMMA layer was coated on Si wafer by a sol-gel technique with two different thicknesses, $1.5{\mu}m\;and\;0.8{\mu}m$. AISI 52100 bearing steel balls were used as a counterpart of the PMMA coating during the wear. Normal applied load and sliding speed were varied. Wear mechanisms were investigated by examining worn surfaces by an SEM. Under most of sliding test conditions, the thicker layer with the thickness of $1.5{\mu}m$ showed lower fiction coefficient than the thinner layer. Effects of sliding speed and counterpart's radius on the frictional behavior were varied depending on the thickness of the coating layer.

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Dry sliding wear behavior of plain low carbon dual phase steel by strain hardening and oxidation (가공경화와 산화층 형성에 의한 이상조직 저탄소강의 건식 미끄럼 마멸 거동)

  • Yu, H.S.;Kim, Y.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.149-152
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    • 2006
  • Dry sliding wear behavior of low carbon dual phase steel, of which microstructure consists of hard martensite in a ductile ferrite matrix, has been investigated. The wear characteristics of the dual phase steel was compared with that of a plain carbon steel which was normalized at $950^{\circ}C$ for 30min and then air-cooled. Dry sliding wear tests were carried out using a pin-on-disk type tester at various loads of 1N to 10N under a constant sliding speed condition of 0.2m/sec against an AISI 52100 bearing steel ball at room temperature. The sliding distance was fixed as 1000m for all wear tests. The wear rate was calculated by dividing the weight loss measured to the accuracy of $10^{-5}g$ by the specific gravity and sliding distance. The worn surfaces and wear debris were analyzed by SEM, EDS and a profilomter. Micro vickers hardness values of the cross section of worn surface were measured to analyze strain hardening behavior underneath the wearing surfaces. The were rate of the dual phase steel was lower than the plain carbon steel. Oxidation on the sliding surface and strain hardening were attributed for the higher wear resistance of the dual phase steel.

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Effects of Hardness on Sliding Wear Behavior of Tempered Bearing Steel (베어링강의 미끄럼 마모거동에 미치는 Tempering 경도의 영향)

  • Lee, Han-Young
    • Tribology and Lubricants
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    • v.29 no.6
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    • pp.360-365
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    • 2013
  • In this study, sliding wear tests were conducted to investigate the effects of tempered hardness on the sliding wear behavior of bearing steel. At a sliding speed of 0.3 m/s, the wear resistance of bearing steel with a tempered hardness of HRC 54 was superior to that with HRC 62. It was found that bearing steel with HRC 54 showed a strong tendency for the occurrence of oxidation wear at that speed, compared to that with HRC 62. This would be due to the troostitic structure of bearing steel with HRC 54, which is highly susceptible to corrosion. In this context, it is considered that sliding wear behavior could be affected by the corrosion resistance of the material.

Sliding Wear and Fretting Wear of Steam Generator Tube Materials (증기발생기 튜브재질의 미끄럼 마멸 및 프레팅 마멸 특성)

  • 김동구;조정우;이영제
    • Tribology and Lubricants
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    • v.17 no.5
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    • pp.380-385
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    • 2001
  • In nuclear power steam generators, high flow rates can induce vibration of the tubes resulting in fretting wear damage due to contacts between the tubes and their supports. In this paper the fretting wear tests and the sliding wear tests were performed using the steam generator tube materials of Inconel 600 and 690 against STS 304. Sliding tests with the pin-on-disk type tribometer were done under various applied loads and sliding speeds at air environment. Fretting tests were done under various vibrating amplitudes and applied normal loads. From the results of sliding and fretting wear tests, the wear of Inconel 600 and 690 can be predictable using the work rate model. Depending on normal loads and vibrating amplitudes, distinctively different wear mechanisms and often drastically different wear rates can occur. It was found the results that the wear coefficients for Inconel 600 and 690 were 262.3$\times$10$\^$-15/Pa$\^$-1/ and 209.2$\times$10$\^$-15/Pa$\^$-1/, respectively. This study shows that Inconel 690 can provide much better wear resistance than Inconel 600 in air.

Sliding Wear Mechanism of Ultra-Fine Grained Low Carbon Dual Phase Steel as n Function of Applied Load (결정립 미세화에 따른 이상조직 탄소강의 하중에 따른 마멸 기구)

  • Yu, H.S.;Yi, S.K.;Shin, D.H.;Kim, Y.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.421-424
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    • 2007
  • Dry sliding wear behavior of ultra-fine grained (UFG) plain low carbon dual phase steel, of which microstructure consists of hard martensite in a ductile ferrite matrix, has been investigated. The wear characteristics of the UFG dual phase steel was compared with that of a coarse grained dual phase steel under various applied load conditions. Dry sliding wear test were carried out using a pin-on-disk type tester at various loads of 1N to 100N under a constant sliding speed condition of 0.20m/s against an AISI 52100 bearing steel ball at room temperature. The sliding distance was fixed as 1000m for all wear tests. The wear rate was calculated by dividing the weight loss, measured to the accuracy of 10-5g by the specific gravity and sliding distance. The worn surfaces and wear debris were analyzed by SEM, EDS and profilometer. Micro-vickers hardness of the cross section of worn surfaces were conducted to analyze strain hardening underneath the contact surfaces. The wear mechanism of the UFG dual phase steel was investigated with emphasis on the unstable nature of the grain boundaries of the UFG microstructure.

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Friction and Wear at Dry Sliding Low Carbon Steel Surfaces Under Vacuum Conditions (진공분위기 내에서 건조마찰 미끄럼운동을 하는 저탄소강 표면의 마찰마모 특성)

  • 공호성;윤의성;권오관
    • Tribology and Lubricants
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    • v.10 no.3
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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.

Sliding Wear Mechanism of Ultra-Fine Grained Low Carbon Dual Phase Steel as a Function of Applied Load (경정립 미세화에 따른 이상조직 탄소강의 하중에 따른 마멸기구)

  • Yu, H.S.;Yi, S.K.;Shin, D.H.;Kim, Y.S.
    • Transactions of Materials Processing
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    • v.16 no.4
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    • pp.299-303
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    • 2007
  • Dry sliding wear behavior of ultra-fine grained(UFG) plain low carbon dual phase steel, of which microstructure consists of hard martensite in a ductile ferrite matrix, has been investigated. The wear characteristics of the UFG dual phase steel was compared with that of a coarse grained dual phase steel under various applied load conditions. Dry sliding wear test were carried out using a pin-on-disk type tester at various loads of 1N to 100N under a constant sliding speed condition of 0.20m/s against an AISI 52100 bearing steel ball at room temperature. The sliding distance was fixed as 1000m for all wear tests. The wear rate was calculated by dividing the weight loss, measured to the accuracy of 10-5g by the specific gravity and sliding distance. The worn surfaces and wear debris were analyzed by SEM, EDS and profilometer. Micro-vickers hardness of the cross section of worn surfaces were conducted to analyze strain hardening underneath the contact surfaces. The wear mechanism of the UFG dual phase steel was investigated with emphasis on the unstable nature of the grain boundaries of the UFG microstructure.