• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1996년도 제23회 춘계학술대회
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• pp.93-98
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• 1996

Friction and wear characteristics of metals in dry and boundary lubricated sliding conditions are observed experimentally using pin-on-disk and pin-on-plate type tribotesters. The motivation of this research is to investigate the effect of sliding history on the tribological behavior of metals. Cu and SM45C steel materials were used for the experiment. The results show that in dry condition the fictional behavior as well as wear of the specimens differed between uni-directional and bi-directional sliding conditions. The friction coefficient values, wear profile and optical micrograph of the wear track are presented.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1990년도 제11회 학술강연회초록집
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• pp.45-52
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• 1990

고도의 신뢰도를 요구하는 정밀기계의 보편화는 트라이볼로지 요소중에서 밀봉기능에 관련된 시일의 해석 및 설계가 커다란 관심사로 부각되었다. 특히 고속회전을 요하는 경우에 대한 회전 시스템의 동적 안정성은 대단히 중요하다. 미끄럼 접촉운동을 하고 있는 기계평면시일의 시일링 간극은 대단히 작기 때문에 시일의 접촉면에서 형상이 변화하게 되면 시일 성능은 커다란 영향을 받게 된다. 시일의 접촉표면 가공시 발생되는 평면도(flatness), 조립시의 회전축과 시일축 사이의 중심 맞추기의 어려움, 회전축의 자중량 등 때문에 발생되는 회전링 사이의 상대적인 경사도(misalignment)는 시일의 동적 불안정성에 영향을 준다. 또한 상대 접촉 운동면에서 경계 또는 고체 마찰에 의한 마멸의 진행은 시일의 코닝(coning) 현상을 일으킨다. 본 연구에서는 비압축성 유체가 온도의 영향을 받아 점도가 선형적으로 변화하는 경우에 대한 시일링 간극 내에서의 압력분포를 유한차분법을 이용하여 해석하였다. 여기서 얻어진 결과를 이용하여 시일의 축력과 모우멘트를 해석함으로써 시일의 동적 불안정성에 대하여 논하였다. 이 때 기계평면 시일의 형상은 코닝이 있고, 시일의 중심축이 경사진 경우를 고려하였다.

• Tribology and Lubricants
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• 제15권2호
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• pp.171-177
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• 1999

Many lubricated systems experience boundary lubrication condition during operation. However, the friction and wear characteristics of boundary lubrication are not clearly understood. In this work the factors which affect the friction and wear between boundary lubricated metallic surfaces are investigated. Experiments were performed using a pin-on-disk type tester with pure aluminum, pure copper, and SM45C steel as the disk material and steel, stainless steel and bearing ball as the ball. The experimental conditions were determined according to the Taguchi experimental method. From the experimental results, the major factors that influence the friction and wear characteristics of boundary lubrication could be identified.

• Tribology and Lubricants
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• 제17권5호
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• pp.399-405
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• 2001

In this paper the ball-on-disk type sliding tests with boundary lubricated steels were carried out to verify the relation between surface profiles and wear as well as scuffing. Three kinds of surface roughness and asperity radius were produced on AISI 1045 steels using the different processes of grinding and polishing. Frictional forces and time to scuffing were measured. Also, the shape and amount of wear particles were analyzed to compare with original profiles. From the tests, it was confirmed that the size of wear particles are very related to original surface profile. The time to failures and wear amounts were sensitive to the surface spacing. The large surface spacing shows much longer sliding life and smaller wear amount than the others. Time to scuffing was increased with increasing surface profile spacing. The sire of wear particles was increased and the amount was decreased with increasing surface profile spacing. Wear volume and wear rate K were decreased with increasing surface profile spacing. And after sliding tests, surface cracks of inner parts of the wear track occurred scuffing were observed and compared the differences about each specimen having the different surface profile spacing.

• Tribology and Lubricants
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• 제12권3호
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• pp.12-25
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• 1996

The friction and wear behaviors of ceramics against steels with lubricants were investigated and compared with those observed in air. Lubrications wbre done by a water and a commercial engine oil as received. The investigated ceramics were $Al_{2}O_{3}$, SiC, and $Si_{3}N_{4}$. Steels with 0.2 wt.% C were heat treated to obtain tempered structure. A cylinder-on-plate tribometer with rotated sliding motion was used to carry out the experiments. In the experiments reported here, the ranges of different testing speeds and loads were used. It was found that the friction and wear characteristics of tested pairs were significantly influenced by environments. In water and oil environments the wear of ceramics was reduced from 10$^{-6}$ g/s down to 10$^{-8}$ g/s in dry sliding at the same values of the frictional power which are the products of the friction coefficient, the load and the sliding speed. SiC showed excellent wear resistant behavior in water sliding, which was the lowest among tested ceramics, but it was, very poor in oils. In case of $Si_{3}N_{4}$, the wear rates were very low under oil environment, but the highest in water. The wear rates of $Al_{2}O_{3}$ were very low in both lubricating conditions at low values of the frictional power, but high at high values of the frictional power.