• Title/Summary/Keyword: Wear Coefficient

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Effect of Vibrational Amplitude on Friction and Wear Properties of Magnetorheological Elastomer (진폭에 따른 자기유변탄성체의 마찰 특성 연구)

  • Lian, Chenglong;Lee, Kwang-Hee;Lee, Chul-Hee
    • Tribology and Lubricants
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    • v.32 no.2
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    • pp.39-43
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    • 2016
  • Magnetorheological elastomers (MREs) are a type of “smart” material, and their properties can be controlled rapidly and reversibly under the influence of an external stimulus. The application of an external magnetic field can change the shear modulus, hardness, and friction coefficient of MREs. The friction can cause vibration; moreover, the vibration can affect friction. The change of friction depends on the relative motion, normal force, roughness of the rubbing surfaces, material type, temperature, lubrication, relative humidity, and vibration condition. As MREs are a type of “smart material,” their friction coefficient can be reduced by applying an external magnetic field—the applications of this feature in engineering have been widely studied. However, the friction properties of MREs under vibration have not been tested to date. In this study, MRE samples and a reciprocating friction tester were fabricated. The friction coefficient was measured to evaluate the friction properties under various vibration conditions; subsequently, the wear depth and wear surface profile of the MRE were observed in order to evaluate the wear properties. The results show that the friction coefficient of the MREs decreased when a magnetic field was applied. Moreover, the friction coefficient decreased when the vibrational amplitudes increased. The wear depth of the MRE also decreased as the vibrational amplitudes increased.

Effect of MoS$_2$ and $Fe_2O_3$ Additives on the Tribological Behavior of the Plasma Sprayed Zirconia Based Coatings (MoS$_2$$Fe_2O_3$ 첨가제가 지르코니아계 용사코팅층의 마모마찰 특성에 미치는 영향)

  • 신종한;임대순;안효석
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1997.10a
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    • pp.93-99
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    • 1997
  • High Temperature wear behavior of plasma sprayed ZrO$_2$ and MoS$_2$, $Fe_2O_3$ coatings were investigated for high temperature wear resistance applications. The MoS$_2$, $Fe_2O_3$ added powders containing 2.5, 5.0, 7.5, 10.0 mol% of $MoS_2$, $Fe_2O_3$ for plasma spray were made by spray drying method. Wear test were performed at temperature ranges from room temperature to 600$\circ$C. The microstructural change of coatings and the worn. surface were examined by SEM and XRD. In ZrO$_2$ coating, the coefficient of friction and wear amount of room temperature to 400$\circ$C was increased with temperature and decreased with temperature over 400$\circ$C. The coefficient of friction and wear amount of MoS$_2$ added coatings were increased with temperature, but those of $Fe_2O_3$ added coatings had lower coefficient of friction and higher wear resistance than ZrO$_2$ coating.

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Friction and Wear Characteristics of Silica/Epoxy Composites for various Particle Size (입자지름의 변화에 따른 실리카 복합재료의 마찰 및 마모 특성)

  • Koh, Sung-Wi;Kim, Hyung-Jin;Kim, Kae-Dong;Kim, Chang-Soo
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2006.11a
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    • pp.141-144
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    • 2006
  • In this study, the friction and wear characteristics of pure epoxy and silica-filled epoxy resin composites with average silica particle diameter of $6-33{\mu}m$ were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials against SiC abrasive paper were determined experimentally. The cumulative wear volume tended to increase nonlinearly with increase of sliding distance and depended on diameter of the silica particle for all these composites. The sliding wear tests of the materials demonstrated that the friction coefficient and the wear rate of silica filled epoxy composites were lower than those of the pure epoxy. silica filled epoxy.

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Effects of Additives on the Friction and Wear Properties of PTFE Composites (PTFE 복합재료의 마찰 . 마모 특성에 미치는 첨가제의 영향)

  • 김용직;엄수현;김윤해
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 1999.11a
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    • pp.88-94
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    • 1999
  • Recently, PTFE-polyimide composites are being used self-lubricating parts for industrial field. Thus, this study is mainly concerned with friction and wear properties for the piston ring of non-lubricating air compressor which made of PTFE-polyimide composites. The friction and wear test was carried out for the different composition ratio under the atmosphere room temperature and constant load of 7.69N and their friction and wear properties were compared with each other at various sliding speed. Notable results are summarized as follows. PTFE 100% showed that friction coefficient was almost same values at 0.94 and 1.88m/s but the value was decreased at 2.83m/s because the friction temperature is higher than low speed. PTFE 80%-PI 20% showed the lowest mean friction coefficient at 2.83m/s. PTFE 20%-PI 80% showed the highest friction coefficient at 0.94m/s and the value was decreased at high speed but the value is higher than other materials except PTFE 100 %. PI 100% showed the highest friction coefficient at 0.94 and 1.88m/s because adhesive wear mainly occurred that speed. PTFE 100% showed highest specific wear rate on the whole. Specific wear rate of PTFE 80%-PI 20% was almost the same value with PTFE 20%-PI 80%. PI 100% showed the lowest value at high sliding speed because the friction surface was thicken and carbonated by high friction temperature.

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Friction and Wear Properties of Cu and Fe-based P/M Bearing Materials

  • Tufekci Kenan;Kurbanoglu Cahit;Durak Ertugrul;Tunay R. Fatih
    • Journal of Mechanical Science and Technology
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    • v.20 no.4
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    • pp.513-521
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    • 2006
  • The performances of porous bearings under different operating conditions were experimentally investigated in this study. Material groups studied are 90%Cu + 10%Sn bronze and 1%C + % balance Fe iron-based self-lubricating P/M bearings at constant (85%) density. In the experiments, the variation of the coefficient of friction and wear ratio of those two different group materials for different sliding speeds, loads, and temperatures were investigated. As a result, the variation of the friction coefficient-temperature for both constant load, and constant sliding speed, friction coefficient-average bearing pressure, PV-wear loss and temperature-wear loss curves were plotted and compared with each other for two materials, separately. The test results showed that Cu-based bearings have better friction and wear properties than Fe-based bearings.

A Study on Wear Characteristics of Degraded Stainless Steel (열화된 스테인리스강의 마모특성에 관한 연구)

  • Cho, Sung-Duck;Ahn, Seok-Hwan;Nam, Ki-Woo
    • Journal of Power System Engineering
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    • v.21 no.6
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    • pp.21-30
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    • 2017
  • This study deals with the characteristics of degraded stainless steel. Stainless steel is heat treated to ensure mechanical properties when designing or manufacturing machinery parts or equipment. In this study, the mechanical properties and wear characteristics of three kinds of stainless steels after artificially heat-treated at 753 K~993 K, where chrome depletion occurs near the grain boundary, were evaluated. The microstructure and fracture surface were also observed. From the results, friction coefficient and wear loss decreased with increasing the heat treatment temperature regardless of the type of stainless steel. Also, as the tensile strength increased, the friction coefficient and wear loss decreased. Wear loss showed proportional to a tendency to increase with increasing friction coefficient.

Characteristics of Wear on Sliding Speed of Glass Fiber Reinforcement Composites (유리섬유강화 복합재료의 미끄럼 속도변화에 따른 마모 특성)

  • Kim, Hyung Jin;Koh, Sung Wi
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.48 no.3
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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.

A Study on the Wear Characteristics of R/S Passing through Curves (곡선부 주행 차량의 마모특성에 관한 연구)

  • Eom, Beom-Gyu;Hyun, Seok;Yang, Kyoung-Tak;Lee, Hi-Sung
    • Proceedings of the KSR Conference
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    • 2008.06a
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    • pp.813-819
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    • 2008
  • For the wear characteristics assessment of Saemaul train passing through curves, an analysis model for multi-car system has been developed. By using this model and ADAMS/Rail, sensitivity analyses have been conducted for the wear characteristics by changing the related parameters. According to the increase of running speed, the wear number, the sliding mean and friction coefficient were increased. At high speed, the wear number, the sliding mean and friction coefficient of left wheel showed higher than right wheel. If the cant increased, the wear number the sliding mean and friction coefficient increased. but decreased based on the balance cant value by the curvature and running speed.

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A Study on the Coating Characteristics of SCM415 Steel (SCM415 강의 코팅특성에 관한 연구)

  • Jang, Jeong-Hwan;Xu, Zhezhu;Kim, Hae-Ji;Kim, Nam-Kyung;Lyu, Sung-Ki
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.2
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    • pp.117-123
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    • 2011
  • The purpose of this study is to show the friction and wear characteristics on the vapor deposited coating layers on the SCM415 steel. In this research, frictional wear characteristic of coating materials such as Ti-series, Cr-series & WC/C and TiAlN+WC/C multilayer coating was investigated under room temperature, normal air pressure and no lubricating condition. Therefore, this study carried out research on the friction coefficient, micro hardness(Hv), surface roughness and wear quantity on the vapor deposited coating layers on the SCM415 steel. As the wear experimental result, the excellence of TiAlN+WC/C multilayer coating has been proven by high micro-hardness, low friction coefficient and wear quantity.

Modification of Thin Film Friction and Wear Models with Effective Hardness

  • Kim, Chang-Lae;Kim, Hae-Jin
    • Tribology and Lubricants
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    • v.36 no.6
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    • pp.320-323
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    • 2020
  • Thin film coatings are commonly exploited to minimize wear and optimize the frictional behavior of various precision mechanical systems. The enhancement of thin film durability is directly related to the performance maximization of the system. Therefore, a fine approach to analyze the thin film wear behavior is required. Archard's equation is a representative and well-developed law that defines the wear coefficient, which is the probability of creating wear particles. A ploughing model is a commonly used model to determine the friction force during the abrasive contact. The equations demonstrate that the friction force and wear coefficient are inversely proportional to the hardness of the material. In this study, Archard's equation and ploughing models are modified with an effective hardness to minimize the gap between the experimental and numerical results. It is noted that the effective hardness is the hardness variation with respect to the penetration depth owing to the substrate effect. The nanoindentation method is utilized to characterize the effective hardness of Cu film. The wear coefficient value considering the effective hardness is more than three times higher than that without considering the effective hardness. The friction force predicted with the effective hardness agreed better with the results obtained directly from the friction force detecting sensor. This outcome is expected to improve the accuracy of friction and wear amount predictions.