• Corrosion Science and Technology
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• 제5권2호
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• pp.52-61
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• 2006

Recently, much of the current development in surface modification engineering are focused on multilayered coatings. Multilayered coatings have the potential to improve the tribological properties. Four different multilayered coatings were deposited on AISI D2 steel. The prepared samples are designed as $WC-Ti_{0.6}Al_{0.4}N$, $WC-Ti_{0.53}Al_{0.47}N$, $WC-Ti_{0.5}Al_{0.5}N$ and $WC-Ti_{0.43}Al_{0.57}N$. The multilayered coatings were investigated with respect to coating surface and cross-sectional morphology, roughness, adhesion, hardness, porosity and tribological behavior. Especially, wear tests of four multilayered coatings were performed by using a ball-on-disc configuration with a linear sliding speed of 0.017 m/sec, 5.38 N load. The tests were carried out at room temperature in air by employing AISI 52100 steel ball ($H_R=66$) having a diameter of 10 mm. The surface morphology, and topography of the wear scars of samples and balls have been determined by using scanning electron spectroscopy (SEM). Results have showed an improved wear resistance of the $WC-Ti_{1-x}Al_xN$ coatings with increasing of Al concentration. $WC-Ti_{0.43}Al_{0.57}N$ coating with the lower surface roughness and porosity with good adhesion enhanced wear resistance.

• 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).

• 한국산학기술학회논문지
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• 제8권3호
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• pp.432-436
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• 2007

자동차 구조용 재료에 대하여 물리적 증착 코팅방법에 의한 트라이볼로지 특성을 연구 하였다. 코팅 재료는 탄화티탄(TiC)과 질화티탄(TiN)이다. 실험은 펠렉스 마찰 마모시험기를 이용하여 하중과 온도에 다양한 조건을 적용하여 마찰과 마모 거동에 대하여 트라이볼로지 특성을 결정하고 평가하였다. 연구결과 코팅하지 않았을 때보다 코팅하였을 때가 윤활 특성이 향상 되었고, 특히 내마모성 및 극압성 그리고 열 안정성이 훌륭하였다.

• 한국세라믹학회지
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• 제46권5호
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• pp.515-519
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• 2009

Carbon layers were fabricated on silicon carbide by chlorination reaction at temperatures between $1000^{\circ}C$ and $1500^{\circ}C$ with $Cl_2/H_2$ gas mixtures. The effect of reaction temperature on the micro-structures and tribological behavior of SiC derived carbon layer was investigated. Tribological tests were carried out ball-on-disk type wear tester. Carbon layers were characterized by X-ray diffractometer, Raman spectroscopy and surface profilometer. Both friction coefficients and wear rates were maintained low values at reaction temperature up to $1300^{\circ}C$ but increased suddenly above this temperature. Variation of surface roughness as a function of reaction temperature was dominant factor affecting tribological transition behavior of carbon layer derived from silicon carbide at high temperature.

• 한국표면공학회지
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• 제54권5호
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• pp.230-237
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• 2021

In this study, the influence of silicon contents on the microstructure, mechanical and tribological properties of Ti-Al-Si-N coatings were systematically investigated for application of cutting tools. The composition of the Ti-Al-Si-N coatings were controlled by different combinations of TiAl₂ and Ti₄Si composite target powers using an arc ion plating technique in a reactive gas mixture of high purity Ar and N₂ during depositions. Ti-Al-Si-N films were nanocomposite consisting of nanosized (Ti,Al,Si)N crystallites embedded in an amorphous Si₃N₄/SiO₂ matrix. The instrumental analyses revealed that the synthesized Ti-Al-Si-N film with Si content of 5.63 at.% was a nanocomposites consisting of nano-sized crystallites (5-7 nm in dia.) and a three dimensional thin layer of amorphous Si₃N₄ phase. The hardness of the Ti-Al-Si-N coatings also exhibited the maximum hardness value of about 47 GPa at a silicon content of ~5.63 at.% due to the microstructural change to a nanocomposite as well as the solid-solution hardening. The coating has a low friction coefficient of 0.55 at room temperature against an Inconel alloy ball. These excellent mechanical and tribological properties of the Ti-Al-Si-N coatings could help to improve the performance of machining and cutting tool applications.

• Tribology and Lubricants
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• 제38권4호
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• pp.162-169
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• 2022

Cobalt-chromium (CoCr)-based alloys have been used for wear applications because of their excellent mechanical properties and wear resistance. With growing concern over environmental problems, CoCr alloys are expected to be used for various tribological applications in degraded lubrication states. To expand the applicability of the materials, data should be accumulated across a broad spectrum of experimental parameters. In this work, the friction and wear characteristics of cobalt-chromium-tungsten (CoCrW) and cobalt-chromium-molybdenum (CoCrMo) alloys are investigated experimentally. The tests are conducted using a pin-on-reciprocating-plate tribotester in dry lubrication. CoCrW and CoCrMo are used as pin and plate materials to investigate the effect of the counter material. The results show that the friction coefficients between CoCrW and CoCrMo generally range from 0.4 to 0.5. The friction coefficient between the CoCrW pin and plate is found to be slightly small. However, the total wear between the CoCrW pin and plate is found to be the largest. In contrast, the total wear between the CoCrW pin and plate is relatively small. Furthermore, CoCrW may cause a faster wear progression of CoCrMo, especially for the case in which CoCrMo is used as the pin material. The results of this work provide a better understanding of the tribological properties of CoCrW and CoCrMo alloys. In addition, this work provides a practical guideline for the use of CoCrW and CoCrMo from the tribological design viewpoint.

• 대한기계학회논문집
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• 제13권3호
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• pp.404-410
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• 1989

본 연구에서는 공업용 세라믹(요업재료등)으로 개발된 것 중에서 가장 마찰특성이 우수할 것으로 간주되고 있는 SiC, Si$_{3}$N$_{4}$와 ZrO$_{2}$ 의 건조 및 윤활마찰특성과 금속과의 마찰특성을 실험적으로 밝히려 한다.

• The Korean Journal of Ceramics
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• 제5권4호
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• pp.317-323
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• 1999

Si3N4-TiC composites have been known as electrically conductive ceramics. $Si_3N_4-TiC$ composites with 2 wt% $Al_2O_3$ and 4 wt% $Y_2O_3$ were hot pressed in $N_2$ environment. The mechanical properties including hardness, fracture toughness, and flexural strength and tribological properties were investigated as a function of TiC content. $Si_3N_4-40$ vol% TiC composite was hot pressed at $1,750^{\circ}C$, $1,800^{\circ}C$, and $1,850^{\circ}C$ for 1, 3 and 5 hours in $N_2$ gas. Mechanical and tribolgical properties depended on microstructures, which were controlled by hte TiC content, hot press temperature, and hot press holding time. However, mechanical properties and tribological behaviors were degraded by the chemical reaction between TiC and N. The chemically reacted products such as TiCN, SiC, and $SiO_2$ were detered by the X-ray diffraction analysis.

• Tribology and Lubricants
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• 제30권5호
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• pp.247-255
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• 2014

Charged polymer chains, i.e., polyelectrolytes, are known to show superior aqueous lubricating properties compared to those of neutral polymer chains, especially in brush conformation. This is primarily because of the incorporation of a large amount of counterions within the polymer layers and the consequently increased osmotic pressure. However, this effect is active only when the polymer chains remain immobilized even under tribostress, which is not realistic for high-contact pressure tribological applications, especially when they are irreversibly immobilized on tribopair surfaces. In contrast, with free polymers, which can be included as surface-active additives in the base lubricant (water), long-term lubricating performance based on "self-healing" properties is readily expected. In order to assess whether the superior aqueous lubricating properties of polyelectrolyte chains are valid for free polymers too, this study reviews recent studies on the tribological properties of many charged biopolymer and synthetic copolymers at a nonpolar, hydrophobic interface. In contrast to the irreversibly immobilized polyelectrolyte chains, free polyelectrolyte chains show inferior aqueous lubricating properties compared to their neutral counterparts owing to charge accumulation and the consequently impeded surface adsorption on the nonpolar surface. Nevertheless, bovine submaxillary mucin (BSM), a representative biopolymer, shows a sufficiently effective surface adsorption and aqueous lubricating capabilities even at neutral pH without losing the polyanionic characteristics.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.369-370
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• 2002

To clarify the tribological properties of biodegradable lubricating oils, the four-ball tests were carried out under dip-feed lubrication using a Soda-type four-ball machine. The test balls were lubricated with soybean oil, rapeseed oil, corn oil and turbine oil. From the tests, the coefficient of friction for all the test balls lubricated with biodegradable lubricating oils was lower than that for the test ball lubricated with turbine oil. Further, from the calculation of the pV value, it was clear that the seizure resistance for all the test balls lubricated with biodegradable lubricating oils was higher than that for the test ball lubricated with turbine oil.