• Title/Summary/Keyword: 마모부피

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Durability evaluation depending on the insert size of conical Picks by the field test (삽입재 크기에 따른 코니컬 커터의 현장 내구성 평가 연구)

  • Choi, Soon-Wook
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.1
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    • pp.49-59
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    • 2019
  • In this study, the durability of conical pick cutter was compared and analyzed by pre- and post-test visual inspection, measurement of weight loss and wear volume through field test on two types of conical pick cutters applied to rotary drum cutter. In the visual inspection, it was found that only 9 inserts were lost in the slim type conical pick cutter. This result show that the thickness of the head cover surrounding a insert was important to maintain the insert during excavation. The weight loss and wear volume of the heavy type conical pick cutter were less than half that of the slim type. From these results, it can be confirmed that heavy type is more useful than slim type in hard rock. It should be noted that, when determining the wear loss of the conical pick cutter, the mutual comparison of the weight measurement and the wear volume measurement results may be different due to the unit weight of the material and the spalling caused by excavation.

Wear Resistance of Crosslinked Ultra-high Molecular Weight Polyethylene (가교된 초고분자량 폴리에틸렌의 내마모성)

  • Im, Chae-Ik;Lee, Gwi-Jong;Jo, Jae-Yeong;Choe, Jae-Bong;Choe, Gwi-Won
    • Journal of Biomedical Engineering Research
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    • v.20 no.1
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    • pp.99-106
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    • 1999
  • Ultra-high molecular weight polyethylene (UHMWPE) was crosslinked in the melt state to enhance wear resistance, Dicumyl peroxide (DCP) and triallyl cyanurate (TAC) was used as a crosslinking agent and a promoter, respectively. With increasing amount of DCP and TAC used, gel content of crosslinked UHMWPE (XUMPE) increased, while the melting temperature, crystallizaiton temperature, crystallinity, and tensile properties decreased. The results of pin-on-disk wear test and ball-on-disk test with small applied load showed reduced wear volumes of XUMPE from that of the unmodified UHMWPE. As the wear mechanism effected in the experimental condition of this study was thought to be deformation rather than adhesion or fatigue, a new parameter, the ratio of maximum contact stress to yield stress, was proposed to correlate well with observed wear resistance. In ball-on-disk wear test with larger applied load, XUMPE showed higher wear volumes than that of the unmodified UHMWPE which were accompanied with increased friction coefficients and surface roughness of the wear tracks. When contact stress was well above yield stress, the failure of XUMPE, as well as deformation, was thought to be much accelerated.

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A STUDY ON WEAR RESISTANCE OF FLOWABLE COMPOSITE RESINS (유동성 복합레진의 마모저항성에 관한 연구)

  • Yun, Yeon-Hee;Kim, Jung-Wook;Lee, Sang-Hoon;Hahn, Se-Hyun
    • JOURNAL OF THE KOREAN ACADEMY OF PEDTATRIC DENTISTRY
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    • v.29 no.2
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    • pp.217-225
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    • 2002
  • When we use the flowable resin on the primary molars for quick handling, one of the most important property is the wear resistance. This study was performed to compare the wear resistance characteristics of four flowable composite resins [Arabesk flow (group 1), Tetric flow (group 2), Aeliteflow (group 3), Filtek flow (group 4)] to that of one control composite resin [Z100 (group 5)]. Specimen discs(n=10), 10mm wide and 2mm thick, were stored in distilled water at $37^{\circ}C$ for 7 days prior to testing. The specimens were subjected to 50,000 strokes at 2 Hz on the MTS system. During the test, the following parameters were maintained: the lateral excursion at 0.4mm, occlusal force at 2-100N with a force profile in the form of a half sine wave. The measurements of volume loss, depth of wear, and Vicker's hardness number of composite resins, and SEM observations of the polished and abraded surfaces were established. One-way ANOVA and Scheffe's multiple comparison test were employed to detect statistically significant differences among the flowable composite resin groups and the control composite group at P<.05. The following results were obtained: 1. Group 3 showed the least volume loss, while group 4 showed the greatest. The mean volume loss increased in the following order: group 3

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베아링강의 미끄럼 마찰하에서 마모 diagram과 마모 천이기구

  • 임대순;김갑배;방건웅;문한규
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.73-77
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    • 1989
  • Ashby등에 의해 비윤활상태에서의 steel의 마모기구도(wear mechanism map)가 작성 발표된바 있다. 이 마모기구도는 지금까지 발표된 steel의 마모연구의 결과를 모아서 seizure, melt dominiated 마모, 산화지배 마모, 소성지배 마모등의 기구가 지배되는 영역을 표준화된 압력과 속도의 변화에 따라 표시한 것이다. 본 연구에서는 베아링강을 모델제료로 하여 마모 diagram을 작성하여 속도와 하중 변화에 따른 mild wear에서 severe wear로의 천이를 관찰하고 각 영역에서의 마모기구에 대해 논하고자 한다. 이 연구에서는 윤활유의 영향을 배제하고 steel ring과 steel pin간의 비윤활 상태에서 마모시험이 행하여졌다. 본 실험에서는 다목적 마모시험을 사용하여 시간에 따라 접촉면적의 형상이 비교적 변하지 않는 pin on ring형태의 시편을 사용하였다. 9.8 N 으로 부터 98 N까지의 하중이, 0.012 m/sec에서 0.012 m/sec까지의 미끄럼 속도에서 마모실험을 행하였다. 각 조합에 따른 조건에서의 마모된 양은 시편의 변이를 측정하여 마모부피를 추정계산하였다.

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Experimental Study to Examine Wear Characteristics and Determine the Wear Coefficient of Ductile Cast Iron (DCI) Roll (Ductile Cast Iron (DCI) 롤의 마모 특성 고찰 및 마모계수 도출을 위한 실험적 연구)

  • Byon, Sang-Min
    • Tribology and Lubricants
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    • v.33 no.3
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    • pp.98-105
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    • 2017
  • A pin-on-disk test is performed to measure the wear volume of a ductile cast iron (DCI) roll when it wears down using a high carbon steel and two alloy steels at different sliding velocities between the roll and the material (steel). Normal pressure is set as constant and test temperatures are 400, 500 and $600^{\circ}C$. In addition, thermal softening behavior of the DCI roll is examined using a high-temperature micro-hardness tester and the surface hardness variation of the DCI roll is expressed in terms of temperature and heating time. Based on experimental data, a wear coefficient used in Archard's wear model for each material is obtained. The wear volume is clearly observed when the test temperature is $400^{\circ}C$ and sliding velocity varies. However, it is not measured at temperatures of $500^{\circ}C$ and $600^{\circ}C$ even with variations in sliding velocity. From the optical photographs of the pin and disk, the abrasive wear is observed at $400^{\circ}C$ clearly, but no at $500^{\circ}C$ and $600^{\circ}C$. At higher temperatures, the pin surface is not smooth and has many tiny caves distributed on it. It is found that wear volume is dependent on the carbon contents rather than alloy contents. Results also reveal that the variations of wear coefficients are almost linearly proportional to the carbon contents of the material.

The Effects of Cure System on Vulcanization Reaction Constant and Physical Properties of Rubber Compounds (가황시스템 변화가 배합고무의 가황반응속도 및 물리적 특성에 미치는 영향)

  • Lee, Seag;Park, Nam Cook
    • Applied Chemistry for Engineering
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    • v.10 no.3
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    • pp.419-426
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    • 1999
  • In this study, the reaction rate constant, activation energy, total crosslinking density, elastic constant, cure properties ($t_5,\;t_{90}$), modulus, and abrasion resistance of rubber compounds were investigated as a function of cure temperatures, cure systems and reinforcing filler loadings. Reaction rate constants showed strong dependence on thc carbon black loading, cure temperature and cure system, and increased sharply with increasing the reaction temperatures. The lowest activation energy was obtained in the efficient cure (EC) system which corresponds to the high level of sulfur to accelerator ratio, and the activation energy was decreased with decreasing the carbon black loadings. The change of carbon black loadings directly affects the modulus and abrasion resistance, but the change of cure system showed various effects on the rubber compounds. Increased carbon black loadings showed the high modulus, improved abrasion resistance and short scorch time but decrease in crosslinking density and elastic constant. Higher crosslinking density and elastic constant were shown in the EC cure system regardless of carbon black loadings, but scorch timc ($t_5$) was not affected by the change of the ratio of sulfur to accelerator. Rapid optimum cure time ($t_{90}$) were showen in the EC cure system. Also, the equivalent cure curve coefficient of rubber compound was 0.96 for conventional cure (CC) system, and 0.94 for semi-efficient cure (SEC) and EC system regardless carbon black loadings. As regarding the abrasion resistance, wear volume showed the logarithmic increase for the loaded weight.

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