• Title, Summary, Keyword: Abrasive wear

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Indentation and Sliding Contact Analysis between a Rigid Ball and DLC-Coated Steel Surface: Influence of Supporting Layer Thickness (강체인 구와 DLC 코팅면 사이의 압입 및 미끄럼 접촉해석: 지지층 두께의 영향)

  • Lee, JunHyuk;Park, TaeJo
    • Tribology and Lubricants
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    • v.30 no.4
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    • pp.199-204
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    • 2014
  • Various heat-treated and surface coating methods are used to mitigate abrasion in sliding machine parts. The most cost effective of these methods involves hard coatings such as diamond-like carbon (DLC). DLC has various advantages, including a high level of hardness, low coefficient of friction, and low wear rate. In practice, a supporting layer is generally inserted between the DLC layer and the steel substrate to improve the load carrying capacity. In this study, an indentation and sliding contact problem involving a small, hard, spherical particle and a DLC-coated steel surface is modeled and analyzed using a nonlinear finite element code, MARC, to investigate the influence of the supporting layer thickness on the coating characteristics and the related coating failure mechanisms. The results show that the amount of plastic deformation and the maximum principal stress decrease with an increase in the supporting layer thickness. However, the probability of the high tensile stress within the coating layer causing a crack is greatly increased. Therefore, in the case of DLC coating with a supporting layer, fatigue wear can be another important cause of coating layer failure, together with the generally well-known abrasive wear.

Manufacture and Application of Diamond Orifices in Abrasive Suspension Jet for Micro Machining (습식 워터 젯 정밀 절삭 가공용 다이아몬드 오리피스 제조 및 응용)

  • Kim, Youn-Chul;Park, Hee-Dong;Jho, Jae-Han;Kang, Suk-Joong L
    • Journal of Korean Powder Metallurgy Institute
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    • v.15 no.6
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    • pp.509-513
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    • 2008
  • High-pressure abrasive entrained jet have rapidly become important machining technology over the last two decades. However, suspension jet by high-pressure has been recently developed for packaging sawing. Ideally, diamond materials should be used for components in abrasive water-jet systems that are subject to high erosive conditions. Using the diamond orifices improve maintenance and extend wear part life. This paper gives insights to using an abrasive suspension jet with diamond orifice. The influences of orifice material and orifice design are evaluated.

Characteristics of Cut Surface by Abrasive Waterjet Cutting of Titanium Alloy (티타늄 합금의 연마제 워터 제트 절단에 의한 절단표면 특성)

  • Chung Nam-Yong;Jin Yun-Ho
    • Journal of Welding and Joining
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    • v.23 no.1
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    • pp.86-93
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    • 2005
  • Abrasive waterjet (AWJ) can provide a more effective means for precision of difficult -to-machining materials such as ceramics and titanium alloys. The present study is focused on the surface roughness of abrasive waterjet cut surfaces. This paper investigated theoretical and experimental surface characteristics associated with abrasive waterjet cutting of titanium alloy Gr2. It is shown that the proper variations of several cutting parameters such as waterjet cutting pressure, cutting speed and cutting depth improve the roughness and characteristics on specimen surfaces produced by AWJ cutting. From the experimental results by AWJ cutting of titanium alloy Gr2, the optimal cutting conditions to improve the surface roughness and precision were proposed and discussed.

Magnetic Abrasive Polishing Technology with Ceramic Particles (세라믹 입자를 이용한 자기연마가공 기술 사례)

  • Kwak, Tae-Soo;Kwak, Jae-Seob
    • Journal of the Korean Society for Precision Engineering
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    • v.30 no.12
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    • pp.1253-1258
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    • 2013
  • Ceramic particles as polishing abrasives are often used in a magnetic abrasive polishing process because they have strong wear resistance. Non-ferromagnetic ceramic abrasives should be mixed with ferromagnetic iron particles for controlling the mixture within a magnetic brush during the polishing process. This study describes the application of the ceramic particles for the magnetic abrasive polishing. The distribution of the magnetic abrasives attached on a tool varies with magnetic flux density and tool rotational speed. From the correlation between abrasive adhesion ratio in the tool and surface roughness produced on a workpiece, practical polishing conditions can be determined. A step-over for polishing a large sized workpiece is able to be selected by a S curve, and an ultrasonic vibration assisted MAP produces a better surface roughness and increases a polishing efficiency.

Micro Grooving of Glass Using Micro Abrasive Jet Machining (Micro Abrasive Jet Machining을 이용한 유리의 미세 홈 가공)

  • Choi, Jong-Soon;Park, Keong-Ho;Park, Dong-Sam
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.10
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    • pp.178-183
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    • 2001
  • Abrasive jet machining(AJM) process is similar to the sand blasting and effectively removes hard and brittle materials. AJM has applied to rough working such as debarring and rough finishing. As the need for machining of ceramics, semiconductor, electronic devices and LCD are increasing, micro AJM is developed, and has become the inevitable technique to micromachining. This paper describes the performance of the micro AJM in micro grooving of glass. Diameter of hole and width of line in grooving is 80${\mu}{\textrm}{m}$. Experimental results showed good performance in micro grooving of glass, but the size of machined groove increased about 2~4${\mu}{\textrm}{m}$. With the fine tuning of masking process and compensation of film wear. this micro AJM could be effectively applied to the micro machining of semiconductor, electronic devices and LCD.

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Study on Influence of Carbon Nanotubes and Alumina Additives to Lubrication and Wear Characteristics (카본 나노튜브 및 알루미나 첨가제가 윤활 및 마모특성에 미치는 영향에 대한 연구)

  • Yun, Chang-Seok;Oh, Dae-San;Kim, Hyun-Joon
    • Tribology and Lubricants
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    • v.33 no.5
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    • pp.220-227
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    • 2017
  • In this work, carbon nanotube and nano-size alumina particle are exploited as additive for lubrication experiment. We used pin-on-disk type tribometer to investigate the tribological characteristics of lubricants with respect to additives and rotational speed. We conducted more than 15 trials of tribotests for two hours for each specimen to obtain stable and accurate frictional force and to create measurable wear track on the substrate. We conducted tests at the boundary/mixed lubrication regime to evaluate the influence of additives on the tribological characteristics. We found that the friction coefficient decreased as the rotational speed increased and as additives were added. In particular, the reduction of friction by adding additives was more significant at low rotational speed than at high rotational speed. We speculate that the additives helped to separate and protect the two contacting surfaces at low speed, while the influence of additives was not significant at high speed since sufficiently thick lubricant film was formed. The wear of the substrate was also reduced by adding additives to the lubricant. However, in contrast to friction, the amount of wear at high rotational speed was less when alumina particles were added to the lubricant than the amount of wear at low speed. We speculate that the increased wear at low rotational speed is as a result of the intermittent abrasive wear caused by alumina particles with uneven shape, while the reduced wear at high speed is as a result of sufficient film thickness which prevented the abrasive wear.

A Study on the surface hardening by repeated sliding contact (반복 미끄럼 접촉에 의한 표면층의 경화에 대한 연구)

  • 박준목;김석삼
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.80-88
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    • 1997
  • Repeated sliding contact wear test was performed with copper specimens to obtain the relationship between wear and surface hardening. Wear surface and wear track section were observed by optical microscopy. Wear volume and micro-vikers hardness of sublayer below wear surface were obtained. These results suggested that wear mechanism depended on contact load than sliding velocity. Therefore wear mechanism was abrasive wear within critical contact load and adhesive wear over critical contact load. Wear rate increased with contact load, sliding distance but decreased with sliding velocity. Surface hardening increased with sliding velocity and sliding distance but decreased with contact load.

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Mechanical Properties and Solid Lubricant Wear Behavior of MMCs Reinforced with a Hybrid of $Al_{2}O_{3}$ and Carbon Short Fibers (알루미나와 탄소단섬유를 혼합한 금속복합재료의 기계적 성질과 고체윤활 마모거동)

  • 송정일;봉하동;한경섭
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.4
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    • pp.968-980
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    • 1995
  • Al/Al$_{2}$O$_{3}$/C hybrid metal matrix composites are fabricated by the direct squeeze infiltration method. From the microstructure of Al/Al$_{2}$O$_{3}$/C composites, uniform distribution of reinforcements and good bondings are found. Optimum processing conditions for preforms and squeeze castings are suggested. Mechanical properties, such as elastic modulus, elongation, 0.2% offset yield strength and ultimate tensile strength are obtained. Through the abrasive were test and wear surface analsis, wear behavior and its mechanism of AC2B aluminum and Al/Al$_{2}$O$_{3}$/C composites can be characterized under various sliding speed conditions. Tensile strenght elongation of Al/Al$_{2}$O$_{3}$/C composites are decreased with increasing the addition of carbon fiber. On the contrary, elastic modulus of Al/Al$_{2}$O$_{3}$/C composites is slightly improved compared with that of the unreinforced matrix alloy. The addition of carbon fiber to al/al$_{2}$O$_{3}$/C composites gives rise to improvement of the wear resistance. Specially, carbon chopped fibers play an important role in interfering sticking between the counter material and metal matirix composites. Al/Al$_{2}$O$_{3}$/C composites are suitable to high speed due to solid lubication of carbon. And wear model of Al/Al$_{2}$O$_{3}$/C composites is suggested by the examination of worn surfaces.

Wear Behaviours of Dental Composite Resins Containing Prepolymerized Particle Fillers (1st Report) (有機複合필러를 包含하는 齒科用 콤포짓트 레진의 磨耗擧動(제1보))

  • 임정일;김교한;김석삼
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.124-130
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    • 1998
  • The wear characteristics and wear mechanisms of dental composite resins were investigated. Composite resins such as Metalii, Silux Plus, Heliomolar and Palfique Estelite were selected as specimens and contents of filler in specimens in order to analyze the effect of Prepolymerized Particle Fillers in friction and wear characteristics. Ball on flat wear tester was used for a wear test. Friction and wear tests are carried out at room temperature. The friction coefficient of Metafil was quite high relatively, and the wear resistance of Silux Plus and Palfique Estelite was better than that of Metafil and Hellomolar at the same experimental condition. The main wear mechanism is plastic flow and abrasive wear by crack propagation.

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