• Title, Summary, Keyword: Abrasive wear

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The Influence of Diamond Abrasive Size on the Life of Tungsten Carbide Wet Drawing Dies (다이아몬드 연마재 입도가 초경 습식신선 다이스 수명에 미치는 영향)

  • Lee, S.K.;Kim, M.A.;Ko, D.C.;Kim, B.M.
    • Transactions of Materials Processing
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    • v.15 no.7
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    • pp.518-523
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    • 2006
  • Wet wire drawing of brass coated steel wire, used for tire reinforcement, is realized with Tungsten Carbide(WC) dies sintered with a cobalt(Co) binder. Dies wear represents an important limitation to the production process and cost savings. Several parameters, such as Co content, WC grain size of tungsten carbide, sintering conditions, and so on, affect on the wear of the drawing die. In this study, the effect of the diamond abrasive particle size on the life of the WC centered dies of the wet wire drawing was investigated. Wet wire drawing experiments were carried out on a wet wire drawing machine. From the experiments, the dies life, dies fracture, wire surface roughness, and wire breaks were investigated. From the results, it was found that the wear of the WC dies increased with the increase in the diamond abrasive particle size.

Wear Characterization of $Al/Al_2O_3$ Composites Reinforced with Hybrid of Carbon Fibers and SiC Whiskers (탄소섬유와 SiC 휘스커를 혼합한 $Al/Al_2O_3$ 복합재료의 마멸특성)

  • 봉하동;송정일;한경섭
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.7
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    • pp.1619-1629
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    • 1995
  • The Al/Al$_{2}$O$_{3}$ SiC and Al/Al$_{2}$O$_{3}$/C hybrid metal matrix composites (MMCs) were fabricated by squeeze infiltration method. Uniform distribution of reinforcements were found in the microstructure of metal matrix composites. Mechanical tests were carried out under various test conditions to clearly identify mechanical behavior of MMCs, and the wear mechanism of Al/Al$_{2}$O$_{3}$/(SiC or C) hybrid metal matrix composites were investigated. The tensile strength and hardness of hybrid composites was resulted in increasing compared with those of the unreinforced matrix alloy. Wear resistance was strongly dependent upon kinds of fiber, volume fraction and sliding speed. The wear resistance of metal matrix composites was remarkably improved by the addition of reinforcements. Especially, the wear resistance of the hybrid composites of carbon fibers was more effective than in the composites reinforced with alumina and SiC whiskers of reinforcements. This was due to the effect of carbon fiber on the solid lubrication. Wear mechanisms of hybrid composites were suggested from wear surface analyses. The major wear mechanism of hybrid composites was the abrasive wear at low to intermediate sliding speed, and the melting wear at intermediate to high sliding speed.

Wear Behaviors of Gas Atomized and Extruded Hypereutectic Al-Si Alloys (가스분무 공정에 의한 과공정 Al-Si 합금 분말 압출재의 마모 거동)

  • Jin Hyeong-Ho;Nam Ki-Young;Kim Yong-Jin;Park Yong-Ho;Yoon Seog-Young
    • Journal of Korean Powder Metallurgy Institute
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    • v.13 no.4
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    • pp.250-255
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    • 2006
  • Wear behaviors of gas atomized and extruded Al-Si alloys were investigated using the dry sliding wear apparatus. The wear tests were conducted on Al-Si alloy discs against cast iron pins and vice versa at constant load of 10N with different sliding speed of 0.1, 0.3, 0.5m/s. In the case of Al-Si alloy discs slid against the cast iron pins, the wear rate slightly increased with increasing the sliding speed due to the abrasive wear occurred between Al-Si alloy discs and cast iron pins. Conversely, in the case of cast iron discs against Al-Si alloy pins, the wear rate decreased with increasing the sliding speed up to 0.3m/s. However, the wear rate increased with increasing the sliding speed from 0.3m/s to 0.5m/s. It could be due to adhesive wear behavior and abrasive wear behavior_between cast iron discs and Al-Si alloy pins.

A Study on the Rolling Bearing Failure Mode of Automotive Transmission(I) (자동차 변속기용 구름베어링의 파손현상 고찰(I))

  • 현준수;문호근;박태조
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.406-411
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    • 2001
  • This paper shows the failure(wear) phenomena of automotive transmission bearings and investigate their characteristics. It was found that the wear mechanism was mainly abrasive wear by the presence of particles in the gear box and the balls was weared more severely than the other tribological contacting parts. The wear of balls alter the bearing contact angle and load ratings, and finally it cause the bearing failure. With close examination of the failed bearing, various countermeasures could be suggested.

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Tribological Behaviors of Carbon-Epoxy Composite with surface grooves (표면 요철을 가지는 탄소 섬유/에폭시 복합재료의 마찰 및 마모 특성)

  • Kim Seong Su;Lee Dai Gil
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.180-184
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    • 2004
  • The tribological behavior of carbon epoxy composites whose surfaces have many small grooves of $100\mu m$ width was experimentally investigated with respect to the sliding direction against groove orientation, surface pressure (P) and velocity (V). The wear mechanism of the composites was observed to calculate the wear volume with respect to the friction coefficient using scanning electron microscopic (SEM). Experimental results show that the abrasive wear is dominant wear mechanism for the grooved composite surface and the friction and wear are greatly reduced when the sliding direction is parallel to the axis of groove because abrasive particles are removed through the grooves effectively.

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An Investigation of the Enhancement of Abrasive Ability of Diamond Film by Surface Modification (다이아몬드 박막의 표면 개질을 통한 연마성능 향상에 대한 실험적 고찰)

  • 나종주;이구현;남기석;이상로;백영준
    • Tribology and Lubricants
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    • v.20 no.1
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    • pp.1-6
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    • 2004
  • In order to identify the effect of lubricant films on abrasive abilities of diamond films, wear rates of Ruby balls slid over as grown diamond films and polytetrafluoroethylene films coated diamond films were compared by using pin-on-disk tribometer. Wear scars of Ruby balls were measured by SEM. Results showed that wear rates of Ruby balls slid over polytetrafluoroethylene coated diamond films were about 4 times lager than as grown diamond films. Coefficients of friction decreased with sliding distance at diamond disks but were almost unchanged at polytetrafluoroethylene coated ones. These results came from behaviors of wear debris, which adhered more strongly in the tracks of as grown diamond films than polytetrafluoroethylene coated ones.

Wear Characteristics of Metal Ball and Seat for Metal-Seated Ball Valve (금속 볼 밸브의 볼·시트 마멸 특성에 관한 실험적 연구)

  • Bae, Junho;Chung, Koo-Hyun
    • Tribology and Lubricants
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    • v.32 no.1
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    • pp.32-37
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    • 2016
  • The wear characteristics of metal ball and seat in a metal-seated ball valve significantly affect the performances such as leakage and valve torque. In this work, the wear characteristics of metal ball and seat are experimentally investigated. A stainless steel ball and seat with a high corrosion-resistant coating are prepared and a component level test was performed. The hardness and surface roughness of specimens cut from the metal ball and seat are measured before and after the test using a micro-Vickers hardness tester and confocal microscopy, respectively. In order to assess the wear characteristics, the surfaces of the specimens are carefully examined after the test. The confocal microscope data show that the surface roughness values of both the ball and seat increase by a factor of 3-4, which may lead to an increase in valve torque. However, the wear of the seat is found to be more significant than that of the ball. In addition, a comparison of the surfaces of the ball and seat before and after testing revealed that adhesive and abrasive wear are the major wear mechanisms. The results of this study may aid in the design of metal-seated ball valves from the tribological point of view.

Effect of Matrix Phase on the Abrasive Wear Behavior of the High Cr White Iron Hardfacing Weld Deposites (고크롬 철계 오버레이용접층의 긁힘마모거동에 미치는 기지상의 영향)

  • 백응률
    • Journal of Welding and Joining
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    • v.16 no.1
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    • pp.114-124
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    • 1998
  • The effect of matrix phase (austenite, pearlite, martensite) on the low stress abrasion resistance in the chromium-carbide-type high Cr white iorn hardfacing weld deposites has been investigated. In order to examine matrix phase, a series of alloys with different matrix phase by changing the ratio of Cr/C system by heat treatment were employed. The alloys were deposited twice on a mild steel plate using self-shielding flux cored arc welding process. The low stress abrasion resistance of the alloys against sands was measured by the Dry Sand/Rubber Wheel Abrasion Test(RWAT). Even though formation of pearlite phase in the matrix showed higher hardness than that of austenite, there was no observable difference in wear resistance between the pearlite and austenite phase for the same amount of chromium-carbide in the matrix. On the other hand, the formation of martensitic phase,, from heat treated austenitic alloys (high content of Cr), enhanced wear resistance due to its fine secondary precipitates.

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Sliding Contact Analysis between Rubber Seal, a Spherical Particle and Steel Surface (시일과 스틸면 사이에 구형 입자가 있는 미끄럼 접촉 해석)

  • Park, Tae-Jo;Lee, Jun-Hyuk
    • Tribology and Lubricants
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    • v.28 no.1
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    • pp.1-6
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    • 2012
  • In this paper, a three elastic body sliding contact problem is modeled to investigate more precise wear mechanisms related with the sealing surface. A 3-D finite element contact model, a small spherical elastic particle, PTFE seal and steel surface, is solved using a nonlinear finite element code MARC. The deformed seal and steel surface shapes, von-Mises and principal stress distributions are obtained for different seal sliding distances. The entrapped small particle within PTFE seal results in very high stresses on the steel surface which exceeded its yield strength and produce plastic deformation such as groove and torus. The sealing surface could also be worn down by sub-surface fatigue due to intervening small particles together with the well-known abrasive wear. Therefore the proposed contact model adopted in this paper can be applied in design of various sealing systems, and further studies are required.

Study on the Lapping Characteristics of Sapphire Wafer by using a Fixed Abrasive Plate (고정 입자 정반을 이용한 사파이어 기판의 연마 특성 연구)

  • Lee, Taekyung;Lee, Sangjik;Jo, Wonseok;Jeong, Haedo;Kim, Hyoungjae
    • Tribology and Lubricants
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    • v.32 no.2
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    • pp.44-49
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    • 2016
  • Diamond mechanical polishing (DMP) is a crucial process in a sapphire wafering process to improve flatness and achieve the target thickness by using free abrasives. In a DMP process, material removal rate (MRR) is a key factor to reduce process time and cost. Controlling mechanical parameters, such as velocity and pressure, can increase the MRR in a DMP process. However, there are limitations of using high velocities and pressures for achieving a high MRR owing to their side effects. In this paper, we present the lapping characteristics and improvement of MRR by using a fixed abrasive plate through an experimental study. The change in MRR as a function of velocity and pressure follows Preston's equation. The surface roughness of a wafer decreases as the plate velocity and pressure increases. We observe a sharp decrease in MRR over the lapping time at a high velocity and pressure in the velocity and pressure test. An analysis of surface roughness (Rq and Rpk) indicates that wear of abrasives decreases the MRR sharply. In order to investigate the effect of abrasive wear on the MRR, we utilize a cutting fluid and a rough wafer. The cutting fluid delays the wear of abrasives resulting in improvement of MRR drop. The rough wafer maintains the MRR at a stable rate by self-dressing.