• Tribology and Lubricants
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• 제35권5호
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• pp.286-293
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• 2019

In friction and wear tests that use friction force microscopy (FFM), the wear debris transfer to the tip apex that changes tip radius is a crucial issue that influences the friction and wear performances of films and coatings with nanoscale thicknesses. In this study, FFM tests are performed for bilayer $MoS_2$ film to obtain a better understanding of how geometrical and chemical changes of tip apex influence the friction and wear properties of nanoscale molecular layers. The critical load can be estimated from the test results based on the clear distinction of the failure area. Scanning electron microscopy and energy-dispersive spectroscopy are employed to measure and observe the geometrical and chemical changes of the tip apex. Under normal loads lower than 1000 nN, the reuse of tips enhances the friction and wear performance at the tip-sample interface as the contact pair changes with the increase of tip radius. Therefore, the reduction of contact pressure due to the increase of tip radius by the transfer of $MoS_2$ or Mo-dominant wear debris and the change of contact pairs from diamond/$MoS_2$ to partial $MoS_2$ or Mo/$MoS_2$ can explain the critical load increase that results from tip reuse. We suggest that the wear debris transfer to the tip apex should be considered when used tips are repeatedly employed to identify the tribological properties of ultra-thin films using FFM.

• 한국공작기계학회논문집
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• 제12권5호
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• pp.8-14
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• 2003

The characteristics of grinding and wear behavior of diamond wheel for grinding ceramic materials was investigated in this study. In case of $Si_3N_4$, the wear of wheel was large, the finding force was relatively stable and the fluctuation of surface roughness n small. On the other hand in case of $Al_2O_3$ and $ZrO_2$, the wear of wheel and surface roughness were decreasing, the grinding force was increasing. During grinding with vitrified bond wheel, $Si_3N_4$ shows renewal of cutting edge while $Al_2O_3$ and $ZrO_2$ show glazing phenomenon of cutting grains. We have found that it possible to observe the behavior of grinding wheel by grinding ratio, grinding resistance, surface roughness and cutting edge ratio. Through the grinding experiments, it was found that grinding life of diamond wheel is 20 times for $Si_3N_4$, and 40 times fir $Al_2O_3$ and $ZrO_2$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.398-401
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• 1999

We prepared diamond thin films on WC-Co substrate in a mixtured $H_2-CH_4-O_2$, gas, using 13.%MHz RF PACVD. Scanning electron microscopy, X-ray diffraction and Rarnan spectroscopy were used to analyze the characteristics of thin film, and tribometer of ball-on-disk type were used to test the wear resistance between thin film and substrate. The good diamond quality and wear resistance was appeared with cemented tungsten carbide substrate treated with oxygen plasma.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.175-176
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• 2002

Our study is to search for tribological properties of diamond-like carbon (DLC) films as known as anti- wear hard thin film on various polymers. This report deals with the deposition of DLC films on various polymer substrates in vacuum by magnetron radio frequency (RF) sputtering method with using argon plasma and graphite, titanium target. The properties of friction and wear are measured using a ball-on-disk wear -testing machine. The properties of friction and wear have been remarkably improved by DLC coating. Moreover the composition of DLC films has been analyzed by using auger electron spectroscopy(AES). The wear rate of titanium-containing DLC film is lower than that of no-metal-containing DLC film.

• 한국자동차공학회논문집
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• 제18권1호
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• pp.112-119
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• 2010

Recently, as the matters of environmental pollution, the energy exhaustion and alternative energy source have become more important issues, around industrial countries and the effort to improve fuel consumption is progressed continuously for decrease of air pollution. In an effort to improve fuel consumption for passenger cars, the study of DLC (Diamond Like Carbon) coating which is widely known to good wear characteristics come to the forefront. Therefore, in present study, it was investigated to the influence of DLC coating layer for wear characteristics with the piston ring material and then suggested to the development process for advanced automotive engine parts that showed improved wear characteristics. From these results, Finally, it will be contributed to improve the fuel consumption for passenger vehicles.

• 한국생산제조학회지
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• 제18권6호
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• pp.636-641
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• 2009

Recently, expansion of micro-technology parts requires micro-precision machining technology. Micro-groove machining is important to fabricate micro-grating lens and many micro-parts such as microscope lens, fluidic graphite channel etc. Conventional groove fabrication methods such as etching and lithography have some problems in efficiency and surface integrity. But, mechanical micromachining methods using single crystal diamond tools can reduce these problems in chemical process. For this reason, microfabrication methods are expected to be very efficient, and widely studied. This study deals with machinability in micro-precision V-grooves machining of nickel plated layer using non-rotational single crystal diamond tool and 3-axis micro stages. Micro V-groove shape, chip formation and tool wear were investigated for the analysis of machinability of Ni plated layer.

• 한국재료학회지
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• 제15권4호
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• pp.224-232
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• 2005

Dry sliding wear behavior of electro-pressure sintered Fe-Ni and Co-Fe-Ni compacts was investigated. Pin-on-disk wear tests were performed on the sintered Fe-Ni, Co-Fe-Ni disk specimens against alumina $(Al_2O_3)$ and silica $(SiO_2)$ ball counterparts at various loads ranging from 3N to 12N. A constant sliding speed of 0.1m/sec was employed. Wear rate was calculated by dividing the weight loss measured after the test by specific gravity and sliding distance. Worn surfaces and cross sections of them were examined by a scanning electron microscopy, and wear mechanism of the compacts was investigated. Wear characteristics of the compacts were discussed as a function of composition of the compacts. Relationship between the wear rate and mechancial properties of the compact was explored, and effects of the oxide layer that was formed on wearing surface of the compacts on the wear were also studied.

• 한국재료학회지
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• 제22권10호
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• pp.552-561
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• 2012

Diamond-like carbon (DLC) films have been widely used in many industrial applications because of their outstanding mechanical and chemical properties like hardness, wear resistance, lubricous property, chemical stability, and uniformity of deposition. Also, DLC films coated on paper, polymer, and metal substrates have been extensively used. In this work, in order to improve the printing quality and plate wear of polymer printing plates, different deposition conditions were used for depositing DLC on the polymer printing plates using the Pulsed DC PECVD method. The deposition temperature of the DLC films was under $100^{\circ}C$, in order to prevent the deformation of the polymer plates. The properties of each DLC coating on the polymer concave printing plate were analyzed by measuring properties such as the roughness, surface morphology, chemical bonding, hardness, plate wear resistance, contact angle, and printing quality of DLC films. From the results of the analysis of the properties of each of the different DLC deposition conditions, the deposition conditions of DLC + F and DLC + Si + F were found to have been successful at improving the printing quality and plate wear of polymer printing plates because the properties were improved compared to those of polymer concave printing plates.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.80-84
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• 1996

This paper aims at reviewing the Possibility application over normal or abnormal, detection used by AE and the wear characteristics of grinding process. In this study, when diamond bur in dentistry with chosen grinding conditions were tuned at grinding. The variation of grinding resistance and hE signal is detected by the use of AE measuring system. The tests are carried out in accordance with diamond burs and workpiece; arcyl and bovine. According to the experiment results, the following can be expected; AE has the possibility to detect the state normality and abnormality. However, the grinding resistance measuring can find it difficult to detect it. It can be accurately excerpted from AE occurrence pattern in contact start point of diamond bur and bovine, grinding condition and derailment point. It is known that AE$\_$rms/ is well compatible with grinding resistance. According to the increase of the material removal rate, the specific energy of the diamond bur is inclined to decrease and the grinding resistance has a tendency to increase.

• Tribology and Lubricants
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• 제22권3호
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• pp.127-130
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• 2006

DLC (Diamond Like Carbon) films show very desirable surface interactions with high hardness, low friction coefficient, and good wear-resistance properties. The friction behavior of hydrogenated DLC film is dependent on tribological environment, especially surrounding temperature. In this work, the tribological behaviors of DLC (Diamond-like carbon) films, prepared by the radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) method, were studied in elevated temperatures. The ball-on-disk tests with DLC films on steel specimens were conducted at a sliding speed of 60 rpm, a load of 10N, and surrounding various temperatures of $25^{\circ}C,\;40^{\circ}C,\;55^{\circ}C\;and\;75^{\circ}C$. The results show considerable dependency of DLC tribological parameters on temperature. The friction coefficient decreased as the surrounding temperature increased. After tests the wear tracks of hydrogenated DLC film were analyzed by optical microscope, scanning electron spectroscopy (SEM) and Raman spectroscopy. The surface roughness and 3-D images of wear track were also obtained by an atomic force microscope (AFM).