• Tribology and Lubricants
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• v.18 no.5
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• pp.324-332
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• 2002

In order to enhance the thermal stability of binder materials of bonded type solid lubricants, several metal-alkoxide based sol-gel materials such as methyltrimethoxysilane(MTMOS), titaniumisopropoxide$(Ti(Opr^i)_4),$ zirconiumisopropoxide $(Zr(Opr^i)_4)$ and aluminumbutoxide$(Al(Obu^t)_4)$ were chemically modified by epoxy-, acrylic- and fluoro-silane compounds, respectively. Friction and wear characteristics of these hybrid ceramic materials were tested with a micro tribo-tester, and evaluated with respect to both heat-curing temperature and the time. Test results generally showed that hybrid ceramic materials modified by epoxy-silane compounds had a low friction compared to others. And the higher het-curing temperature and the longer heat treatment time resulted in the higher friction and the lower wear. IR spectroscopic analyses revealed that these results were caused mainly by the increased metal oxide content in hybrid ceramics when the heat-curing temperature was over $320^{\circ}C.$

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1044-1048
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• 2006

Nuclear power generation is very dangerous in occasion that skirt of structure by earthquake although it is high effective generation that can make a lot of energies with few raw material. when design, it must consider a lot of problems caused by an earthquake. The seismic analysis of the structure has been great concern in the engineering society with an effort to reduce the severe damages from an earthquake. So the earthquake resistant design is one of the crucial design procedures of a gate valve used in nuclear power generation. The gate valve which has the contact area between stem and bellows. Because of the contact area. The gate valve should be given high stress and frictional wear. In this thesis, Considering the gate valve which has some contact distance between stem and bellows. The gate valve which has some contact distance is analyzed by a commercial FEM code of Ansys and Then compared to the gate valve behavior which doesn't have contact distance.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.108-108
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• 2018

무전해 니켈도금 층은 마모, 마찰, 스크래치, tribology 등에 대한 내구성뿐만 아니라 내식성도 우수하여 산업현장에서 널리 적용되고 있다. 일반적으로 무전해 니켈도금 층의 내구성은 경도 값과 직접적인 상관관계를 가지며, 그 값은 약 $400-500H_V$ 정도이다. 이러한 무전해 도금 층에 대하여 약 $400^{\circ}C$에서 1시간 정도 열처리를 실시하면 경도 값은 약 $800-1000H_V$ 정도로 현저히 증가되고 내구성 역시 크게 향상시킬 수 있다. 그러나 해양환경에서 발생되는 캐비테이션 침식 부식에 대한 무전해 니켈도금 층의 열처리에 관한 연구는 거의 전무한 상태이다. 따라서 본 연구에서는 회주철의 캐비테이션 침식 부식을 방지하기 위해 무전해 니켈도금 후 다양한 온도와 시간으로 열처리를 실시하여 도금 층의 캐비테이션 침식 부식 특성을 평가하고자 하였다. 무전해 니켈코팅을 위한 모재는 회주철(FC250)을 $19.5mm{\times}19.5mm{\times}5mm$의 크기로 가공하였다. 도금조로 500mL 비커를 사용하였으며, 모든 시험편은 2시간 동안 무전해 니켈도금을 실시하였다. 그리고 캐비테이션 실험은 ASTM G32 규정에 의거하여 천연해수 내 $30^{\circ}C$에서 $50{\mu}m$의 진폭으로 실시하였다. 그 결과 열처리 적용 시 EN 도금의 표면경도가 현저히 증가하여 캐비테이션 침식 부식 저항성이 상당히 개선되었다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.38-38
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• 2018

TiMoN 코팅층은 우수한 내마모 특성과 낮은 마찰계수를 보여 많은 연구가 진행되고 있다. 본 연구에서는 음극아크 증착으로 질소 가스 유량, 아크 전류, 기판 전압 등 공정 변수를 제어하여 TiMoN 코팅층을 스테인리스와 초경 기판 위에 제조하고 색상, 미세구조, 경도 등 물리적 특성을 평가하였다. TiMo 타겟은 Mo가 약 8 at.% 함유되어 있으며 직경은 80 mm이었다. 색차계를 이용하여 TiMoN 코팅층의 색상을 분석한 결과, 질소 유량이 증가할수록 $a^*$와 $b^*$ 값이 증가하는 경향을 확인하였다. 질소 유량 90 sccm으로 제조한 TiMoN 코팅층은 TiN 코팅층과 유사한 색상을 보였다. TiMoN 코팅층의 조성을 에너지분산형 분광기(energy dispersive spectroscopy)로 분석한 결과, 타겟과 유사한 조성을 보였다. TiMoN 코팅층의 단면을 주사전자현미경으로 관찰한 결과, 주상정 형성이 확인되었으며 코팅층 표면에는 음극 아크 공정 시 발생하는 거대입자가 발견되었다. 질소 유량 50 sccm으로 제조한 TiMoN 코팅층은 약 3000 Hv의 경도 값을 보였다. X-선 분광기로 TiMoN 코팅층의 결정성을 분석한 결과, TiN과 유사한 합금상이 형성된 것을 확인할 수 있었다. TiMoN 코팅층은 TiN과 유사한 색상을 보였으며 경도는 TiN보다 높은 값을 보여 절삭공구, 금속 가공용 부품 등 고경도 코팅층으로 활용이 가능할 것으로 판단된다.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.1
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• pp.33-38
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• 2007

Door guide rail is the core part which guides window when it moves up and down. But when the method of grease lubrication in the core has been used for a long times, its lubrication performance has been weakened. Therefore the method of the solid lubrication such as teflon(PTFE) coating in the rail has been studied to be increased the performance in these days. In this study the friction wear characteristic the surface with teflon coating of door guide rail for automobile has been researched. In 1, 20 Hz frequency friction wear tests the friction coefficient are below 0.188 and 0.213. In indicate test the wear depth is very slight. Therefore the durability to the friction wear in the surface with teflon coating of door guide rail is good. In addition to, the result of this study can make efficient use to a basic study to develop method of test evaluation to door guide rail surface grade. Especially this study will contribute to improve the quality of automobile parts.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.2
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• pp.162-168
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• 2014

The friction and wear characteristics of the rubber matrix composites filled with nano sized silica particles were investigated at ambient temperature by pin-on-disc friction test. The volume fraction of silica particles was 19%. The cumulative wear volume and wear rate of these materials on counterpart roughness were determined experimentally. The major failure mechanisms were lapping layers, deformation of matrix, ploughing, debonding of particles, fracture of particles and microcracking by scanning electric microscopy photograph of the tested surface. The cumulative wear volume showed a tendency to increase with increase of sliding distance. The wear rate of these composites tested indicated low value as increasing the sliding distance.

• Journal of the Korean Ceramic Society
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• v.31 no.9
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• pp.1069-1075
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• 1994

When ceramics are used as the parts of an engine and a machine, the tribological properties are very important. For the preparation of the resistance material for wear applications by the method of Reaction-Bonded Sintering, metal silicon and carbon black are mixed up into SiC powder, and Al2O3 and Fe2O3 are put as an additive. As the general properties, the bending strength and water absortion are measured in the normal temperature and the phase changies are investigated with XRD. The property of the resistance for wear applications is measured with the amount of friction and wear, friction coefficient and maximum asperties. And, the surface of wear is observed with SEM. With the results of this study, the optimal mol ratio of Si : C and the suitable quantity of the mixture of SiC are 7 : 3 and 40 wt%, respectively. In the case of the addition of Al2O3 (2 wt%), the resistance for friction and wear applications is prominent. The bending strength showed the highest peak when Al2O3 (4 wt%) and Fe2O3 (4 wt%) were added. The properties of friction and wear were related with the propagation velocity of crack rather than the bending strength.

• Journal of the Korean Society for Railway
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• v.14 no.4
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• pp.348-353
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• 2011

Iron fillings which were accumulated around the rail was often the cause of abnormal signal in case of signaling equipment using rail as transmission line. Iron fillings were generated on curved section of railroad due to the friction between rail and wheel, and metro line company urged to find the way to remove these iron fillings, because these were often the cause of abnormal signal. Magnetic device for trapping iron fillings around concrete slab tracks is introduced. The characteristics of magnetic device were analyzed using basic design and numerical analysis method. Magnetic device for trapping iron fillings were examined for application to the train which were operating in commercial line.

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.14-21
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• 2003

This study deals with the influence of ceramic coating on characteristics of friction and abrasion of aluminum allot(7075 T6) used in mechanical casting. In this research, frictional wear characteristic of ceramic coating materials such as $A1_2O_3$, $Si_3N_4$, SiC was investigated using aluminum alloy(7075 T6) and stainless 403 cast iron under room temperature and normal air pressure. The coating layer was observed using SEM. The conclusions are as follows: 1) Friction coefficients of $A1_2O_3$, SiC and $Si_3N_4$ are obtained 0.63 0.56 and 0.54 respectively. 2) Abrasion resistance of stainless 403 cast iron with $Si_3N_4$ is the best among the ceramic coating materials. 3) Abrasion mechanism of aluminum alloy(7075 T6) coaled with ceramic material and stainless 403 cast iron is caused by brittle fracture. 4) Coating the ceramic material on the aluminum alloy(7075 T6) can effectively increase the antiwear, impact properties, and corrosion resistance.

• Tribology and Lubricants
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• v.11 no.4
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• pp.28-34
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• 1995

PTFE has good mechanical and chemical stability at wide temperature range, and more over, shows a low value of friction coefficient. On the other hand, it shows cold flow and high wear rate. However, these short comings can be overcome by adding various fillers. In this experiment, PTFE and polyimide powder were mixed into composite and its tribological characteristics was investigated. 100% polyimide was also tested for comparison. The countefface material was a stainless steel (SUS304). Friction and wear tester of ring-on-block type was used at room temperature and under atmosphere. After the wear test, the worn surfaces were examined by optical microscope. The test results show that PTFE-polyimide composite generates. the wear transfer film on both sides of the friction surfaces, and, the friction coefficient and the wear rates are relatively low. 100% polyimide generated little wear transfer films, showed high friction and wear rates, and also showed some problems of vibration and noise. It even damaged the stainless steel countefface. It was concluded that 100% polyimide does not generate transfer film well because its shear resistanbe is high and it stickslips, thus, friction coefficients and wear rates are high. In case of PTFE-polyimide composite, on the other hand, transfer film containing sufficient PTFE adheres and remains on both wear surfaces well enough because PTFE has low shear resistance. Polyimide particles in the composite were proved to be able to bear normal load and does not show stick-slip because they are covered with transfer film containing much PTFE.