• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.37-37
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• 2001

TiN coatings were applied for VarIOUS application fields, because of a good wear-resistance and a high hardness. Typically, TiN thin films show the hardness of 25GPa and friction coefficient of 0.6. However, in many field, one is looking for a more improved tool which has low friction coefficient and high wear resistance. The main motivation of this study is to characterize the influence of copper dopant content on TiN thin films. Ti-Cu-N thin films were deposited onto D2 steel substrates by PVD processing with various magnetron current densities (Cu contents). In this work, we synthesized titanium nitride films similar with reported typical titanium nitride films and synthesized Ti-Cu-N thin films with the addition of elemental copper which is measured improved hardness more than pure TiN films with copper content variables. This films has preferred oriented films of (111) direction. In addition, It was found that there is a strong correlation between content of various metal and film characteristics such as preferred orientation, grain size, hardness and friction coefficient and so, in future study, improved mechanical properties of TiN films can be controlled by change in target current density. The Ti-Cu-N film will show apparent hardness improvement and mechanical properties enhancement, when doping element is added onto TiN thin films. Film structure, chemical composition, mechanical properties were investigated by means of X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy(EDS), wear resistance tester and nanohardness tester.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.2
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• pp.260-266
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• 2002

DLC films were deposited on Si wafer by RF plasma assisted CVD using CH4 gas. Tribological tests were conducted using rotating type ball on disk friction tester in dry air. Four kinds of mating balls were used. The mating balls were made with stainless steel but apply different annealing conditions to achieve different hardness conditions. Testing results in all load conditions showed that the harder the mating materials, the lower the friction coefficient among the three kind of martensite mating balls. In case of austenite balls, the friction coefficients were lower than fully annealed martensite ball. The high friction coefficient in soft martensite balls seems to be caused by the larger contact area between DLC film and ball. The wear tracks of DLC films and mating balls could have proven that effect. Measuring the wear track of both DLC films and mating balls have similar tendency comparing to the results of friction coefficients. Wear rate of austenite balls were also smaller than that of fully annealed martensite ball. The results of effect of applying load showed, the friction coefficients were become decrease when the applying loads exceed critical load conditions. The wear track of mating balls showed that some material transfer occurs from DLC film to mating ball during the high friction process. Raman spectra analysis showed that transferred material was a kind of graphite and contact surface of DLC film seems to undergo phase transition from carbon to graphite during the high friction process.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1219-1224
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• 2006

This paper presents the friction and anti-wear characteristics of nano-oil with n mixture of a refrigerant oil and carbon nano-particles in the thrust slide-bearing of scroll compressors. Frictional loss in the thrust slide-bearing occupies a large part of total mechanical loss in scroll compressors. The characteristics of friction and anti-wear Lising nano-oil is evaluated using the thrust bearing tester for measuring friction surface temperature and the coefficient of friction at the thrust slide-bearing as a function of normal loads up to 4,000 N and orbiting speed up to 3,200 rpm. It is found that the coefficient of friction increases with decreasing orbiting speed and normal force. The friction coefficient of carbon nano-oil is 0.015, while that of pure oil is 0.023 under the conditions of refrigerant gas R-22 at the pressure of 5 bars. It is believed that carbon nano-particles can be coated on the friction surfaces and the interaction of nano-particles between surfaces can be improved the lubrication in the friction surfaces. Carbon nano-oilenhances the characteristics of the anti-wear and friction at the thrust slide-bearing of scroll compressors.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.2
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• pp.91-97
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• 2000

The structure and mechanical properties of TiN and TiCN thin films deposited on STD61 steel substrates by the RF-sputtering methods has been studied by using XPS, XRD, micro-hardness tester, scratch tester, and wear-resistance tester. XPS results showed that the TiCN thin film formed with chemical bonding state. The TiN thin films grew with (111) orientation having the lowest strain energy by compressive stress, whereas the TiCN thin films grew with both (111) and (200) orientation, but (200) orientation having the lowest surface energy becomes dominant as carbon contents increase. The pre-etching treatment of substrate did not affect on the preferred orientation of thin films, but it played an important role in improving mechanical properties of thin films such as the hardness, adhesion and wear- resistance. Especially, the TiCN thin films showed the superior wear resistances due to high hardness and low friction coefficient compared with TiN thin films.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.04a
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• pp.232-241
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• 1997

The tribological behavior for MoS$_2$ bonded films is evaluated according to the international standard testing methods, such as ASTM D 2625(Falex tester) and ASTM D 2714(LFW-1 tester). It has been well known that the tribological behavior for MoS$_2$ bonded films is affected by several factors. However, in this work, the wear life for MoS$_2$ bonded films is mainly experimentally measured with different contact geometry, and evaluated in terms of the frictional heating according to the contact geometry of tribotester. The test results show that the wear life of MoS$_2$ bonded films is significantly affected not only by the frictional heating, but also by the contact pressure, test running-in conditions, and the contact conformity.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.12
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• pp.954-961
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• 2014

Brake squeal noise of KTX is very uncomfortable to passengers and workers in stations. A lot of study has been conducted to inquire into the mechanism of the squeal noise. But understanding of the brake squeal noise is still challenging. In this study, we developed a full-scale tester equipped with a KTX mechanical brake unit. And we measured the vibrational characteristics of each component of the brake unit and compared them with frequency response functions of brake squeal noise measured also in the tester. It was found that the brake squeal noise was more closely related to the vibrational characteristics of the brake pads and hangers in friction condition than those of free components.

• Tribology and Lubricants
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• v.13 no.3
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• pp.20-27
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• 1997

The tribological behavior for $MoS_2$ bonded films is evaluated according to the international standard testing methods, such as ASTM D 2625 (Falex tester) and ASTM D 2714 (LFW1 tester). It has been well known that the tribological behavior for $MoS_2$ bonded films is affected by several factors. However, in this work, the wear life for $MoS_2$ bonded films is mainly experimentally measured with different contact geometry, and evaluated in terms of the frictional heating according to the contact geometry of tribotester. The test results show that the wear life of $MoS_2$ bonded films is significantly affected not only by the frictional heating, but also by the contact pressure, test running-in conditions, and the contact conformity.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.90-99
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• 2000

This report describes the results of analysis, synthesis and evaluation of antimony dithiocarbamates (SbDTC). Sb-DTC were synthesized by reacting antimony oxide with dithiocarbamates whish were prepared by reaction of dialkylamines and carbon disulfide. The chemical structures and properties of synthesized Sb-DTCs in lab. were discussed. The frictional properties of SbDTC were tested with Four-Ball Wear Scar Tester and Four-Ball Extreme Tester by ASTM method.

• Elastomers and Composites
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• v.58 no.2
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• pp.87-94
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• 2023

Abrasion tests of an SBR compound were conducted using four different types of abrasion testers (cut and chip, Lambourn, DIN, and LAT100). The abrasion test results were analyzed in terms of size distributions and morphologies of the wear particles. Most wear particles were larger than 1000 ㎛. The wear particle size distributions tended to decrease as the particle size decreased. Except for the Lambourn abrasion test, the wear particles smaller than 212 ㎛ were rarely generated by the other three abrasion tests, implying that small wear particles were produced through friction by introducing talc powder. Shapes of the wear particles varied depending on the abrasion testers. The wear particles generated from the Lambourn abrasion tester had stick-like shapes. The cut and chip abrasion test showed a clear abrasion pattern, but the DIN abrasion test did not show any specific abrasion pattern. The Lambourn and LAT100 abrasion tests showed irregular abrasion patterns.

• Tribology and Lubricants
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• v.31 no.4
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• pp.183-188
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• 2015

This paper presents the experimental effects of lubricant with nanodiamond particles in sliding friction. In order to improve the performance of lubricants many additives are used, such as MoS₂, cadmium chloride, indium, sulfides, and phosphides. These additives are harmful to human health and to the environment, so alternatives are necessary. One such alternative is nanodiamond powder, which has a large surface area. In order to investigate the effect of nanodiamonds in lubricants under sliding friction, they are dispersed in the lubricant at a variety of concentrations (0 wt%, 0.1 wt%, 0.3 wt%, 0.5 wt%, and 1 wt%) using the matrix synthesis method. Friction and wear tests are performed according to the ASTM G99 method using a pin-on-disc tester at room temperature. The specimens used in this experiment are AISI 52100 ball bearings and AISI 1020 steel discs. During the test, lubricant mixed with nanodiamond is supplied constantly to keep the two bodies separated by a lubricant film. To maintain boundary lubrication, the speed is set to 0.18 m/s and a load of 294 N is applied to the disc through the pin. Results are recorded by using workbench software over the test duration of 10 minutes. Experimental results show that when the concentration of nanodiamond increases, the coefficient of friction decreases. However, above a nanodiamond concentration of 0.5 wt%, both the coefficient of friction and wear volume increase. From this experiment, the optimum concentration of nanodiamond showing a minimum coefficient of friction of 0.09 and minimum wear volume of 0.82 nm² was 0.5 wt%.