• Tribology and Lubricants
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• 제5권1호
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• pp.36-43
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• 1989

Scanning electron microscopic observations were carried out on the worn surface and the wear debris of ceramic materials to investigate the wear mechanism of those in dry rolling contact. It was found from the scanning electron microscopic observations that the wear in ceramic materials is related to brittle fracture and has two types of wear mechanisms, small scale wear and larvae scare wear. Plate-like wear debris were created from the initial surface cracks and defects. The small scale wear was related to real contact area and large scale wear was related to HertzJan contact area. A wear model was proposed on the basis of scanning electron microscopic observations.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.879-880
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• 2006

Effect of phase transformation and grain-size variation of hot-pressed cobalt on its dry sliding wear was investigated. The sliding wear test was carried out against glass (83% $SiO_2$) beads at 100N load using a pin-on-disk wear tester. Worn surfaces, cross sections, and wear debris were examined by an SEM. Phases of the specimen and wear debris were identified by an XRD. Thermal transformation of the cobalt from the hcp $\varepsilon$ phase to the $\gamma$ (fcc) phase during the wear was detected, which was deduced as the wear mechanism of the sintered cobalt.

• Tribology and Lubricants
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• 제32권6호
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• pp.189-194
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• 2016

Wear debris in lubricating oil can be indicative of potential damage to mechanical parts in rotating and reciprocating machinery. Therefore, on-line or in-line monitoring of lubricating components in machinery is of great importance. This work presents a device based on inductive measurement of lubricating oil to detect magnetic wear particles in a tested volume. The circuit in the device consists of Maxwell Bridge and LVDT to measure inductance differences between pure and contaminated oil. The device detects the passage of ferrous particles by monitoring inductance change in a coil. The sensing principle is initially demonstrated at the microscale using a solenoid. The device is then tested using iron particles ranging from $50{\mu}m$ to $100{\mu}m$, which are often found in severely worn mechanical components. The test results show that the device is capable of detecting and distinguishing ferrous particles in lubricating oil. The design concept demonstrated here can be extended to an in-line monitoring device for real-time monitoring of ferrous debris particles. A simulation using the CST code is performed to better understand the inductive response in the presence of magnetic bodies in the oil. The CST simulation further verifies the effectiveness of inductance measurement for monitoring magnetic particles within a tube.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.465-466
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• 2002

In any mechanical system consisting of gears, shafts and/or bearings, the majority of metallic particles deposited into and carried by the lubrication system originate from the deterioration of oil-wetted working surfaces, even in proper lubrication system, due to failure mechanism (s) such as wear, fatigue and fretting corrosion. Determination of the point at which transition from normal to abnormal or to actual damage occurs has become a focus of attention in research activities for years, because it has been recognized that reliable, economic operation can be achieved through appropriate preventative measures. Known collectively from 'all size wear debris analysis' as early failure detection, the methods of testing for damage differ considerably, range from a micron or a submicron size debris analysis to Magnetic Chip Detector (MCD) ferrous debris analysis. This paper will be focused on the utilization of the low-cost analysis techniques for evaluation of industrial machinery condition.

• 한국진공학회지
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• 제7권1호
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• pp.59-65
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• 1998

13.56MHz를 사용하는 r.f.PACVD(Plasma assisted chemical vapor deposition)방법 으로 다층 다이아몬드상 카본(DLC)필름을 Si wafer기판 위에 합성하였다. 다층 DLC필름은 2.5$\mu$m두께의 순수한 DLC필름과 0.2$\mu$m두께의 Si이 함유된 Si-DLC필름으로 구성되었으 며, ball on disk type의 tribometer를 이용하여 대기 중에서 다층 DLC필름의 마모거동을 고 찰하였다. 표면층으로 합성된 Si-DLC필름내의 Si함량이 증가함에 따라 다층 DLC필름과 AISI52100 steel ball 사이에 0.1 이하의 낮은 마찰계수를 유지하는 기간이 증가하였다. 44,000cycle과 158,400cycle의 마모실험 후 측정된 다층 DLC필름의 마모율은 각각 $2.5\times10^{-8}\sim1.8\times10^{-7}\textrm{mm}^3$/rev.과 $7.1\times10^{-9}\sim1.8\times10^{-8}\textrm{mm}^3$/rev.로 나타났다. 158,400cycle의 마모실험 후 측정된 마모율은 내마모 특성이 우수한 DLC필름보다도 2배 정도 우수한 것으로 나타났 다. 마모시험에 의해 형성된 debris의 조성을 분석한 결과, 이런 낮은 마찰계수와 우수한 내 마모 특성은 steel ball의 wear 표면을 덮고 있는 Si oxide debris층의 형성에 따른 결과로 판단되었다. 또한, 이러한 steel ball의 wear scar표면에 형성된 debris층을 제거하여도, 새로 운 Si oxide debris층이 wear scar표면에 다시 생성되어 낮은 마찰계수를 유지하고 있었다.

• Tribology and Lubricants
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• 제17권1호
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• pp.16-21
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• 2001

The wear particles is released from the moving surfaces in gear systems of transmission and its morphology is directly related to the damage and failure to gear system from which the particles originated. It is the effective method for damage condition estimation of automobile transmission gear to observe wear debris in gear oil. We tested with new transmission and took out gear oil according to driving distance. To be applied to damage condition of gear system in transmission of automobile,4 shape parameters of wear particles in gear oil were calculated and wear volume were presumed with the image processing system.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.312-315
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• 2004

A lubricated state of an automobile transmission can not be inspected directly with eyes. Thus, it needs to develop a more general method. Wear debris can be collected from the lubricants of operating transmission of an automobile and its morphology is directly related to the fiction condition of the interacting materials from which the wear particles originated in lubricated transmission. In this paper, to identify the friction condition for transmission gear by neural network, the wear test of ball-on-disk type and the analysis of friction state were carried out for carburized SCM420 and nitrocarburized NT100 under different experimental conditions. The four shape parameters($50\%$ volumetric diameter, aspect, roundness and reflectivity) of wear debris were calculated by the image processing system. They were used as input values to identify the moving condition of transmission gear by the neural network.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.563-567
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• 1996

This paper was undertaken to analyze the morphology of wear debris generating from moving lubricated machine surfaces by image processing. The lubricating wear test was carried out under different experimentaal conditions using the wear test device was made in our laboritory and wear testing specimen of the pin on disk type wear rubbed in paraffine series base oil, byvarying applied load, sliding distance. The four parameters(50% volumetric diameter, aspect, roundness and reflectivity) to describe the morphology have been developed and are outlined in the paper. A system using such techniques promises to obviate the need for subjective, human interpretation of particle morphology in machine condition monitoring, thus overcoming many of the difficulties with current methods and facilitating wider use of wear particle analysis in machine condition monitoring.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.285-290
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• 2000

This paper was undertaken to do morphological analysis of wear debris for slipper-pad of hydrauric rotary acuator. The lubricating wear test was performed under different experimental conditions using the wear test device and wear specimens of the pin on disk type was rubbed in paraffinic base oil by three kinds of lubricating materials. varying applied load, sliding distance. The four shape parameters(50% volumetric diameter, aspect, roundness and reflectivity) are used showed that the four shape parameters of wear debris depend on a kind of the lubricating condition. It was capable of presuming wear volume for slipper-pad of hydrauric rotary acuator on driving time.

• Tribology and Lubricants
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• 제15권2호
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• pp.131-140
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• 1999

This study dealt with some problems occurred in spectrometric oil analysis that has been popularly used for a machine condition monitoring in various fields of industry. One of the problems is that spectrometric technique could not analyze contaminants of large particle (larger than 10 $\mu\textrm{m}$) in lubricating oils. This limitation caused a serious problem in analyzing lubricated machine conditions since wear debris of large size represents better critical machine conditions. In this work, this problem was found to be solved by using a filtration method prior to spectrometric analysis. Another problem could be that spectrometric analysis is incapable of identifying contaminants. This nay mislead the result seriously in practice. This problem was surveyed by analyzing both various types of industrial lubricants and laboratory simulation tests, and the solutions to the problem were suggested in this work.