• 한국세라믹학회지
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• 제32권7호
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• pp.825-831
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• 1995

Reaction-bonded SiC-Si material was fabricated by infiltration of Si melt into a mixture of $\alpha$-SiC and carbon at 175$0^{\circ}C$ under the vacuum atmosphere. Wear properties were analyzed by ball-on-plate wear tester, changing loading weight, sliding speed, sliding time and atmosphere, Results showed that the friction coefficient was decreased with increasing load and sliding velocity. The lowest friction coefficient of 0.05 was obtained under an oil atmosphere. The analysis of the wear surface indicated that the areas wehre particles were pulled out and where free silicon particles worn out preferentially serve as liquid reservoirs to decrease the wear resistance.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.526-530
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• 1996

In this paper, three different types of commercially tools-P20, NC123K and ceramic-have been used to working austempered ductile iron(ADI). In the austempered condition the materials are hard, strong and difficult to machine. Thus, we selected a optimum tool material among three different types of used tools in machining of austempered ductile iron. It was used acoustic emission(AE) to know cutting characteristic for selected tool and flank wear land of the ceramic too. The obtained results are as follows; (1) The ceramic tool among three different types of tools is the best in machining austempered ductile iron. (2) In case of ceramic tool, the amplitude level of AE signal(AErms) is mainly affected bycutting speed in cutting speed in cutting condition and it is proportioned to cutting speed. (3) There have the relationship of direct proportion between the amplitude level of AE signal and flank wear land of the tool. (4) If it find the value of AErms at each cutting speed, the in-process detection to ceramic tool's wear is possible

• 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.

• Journal of Welding and Joining
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• 제10권4호
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• pp.213-221
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• 1992

Al$_{2}$O$_{3}$ ceramic coating layer by gas flame spraying was very porous, therefore it could not have wear and corrosion resistance at all. To get a dense and strong coating layer, a method to infiltrate an alloy into the pores of $Al_{2}$O$_{3}$ ceramic coating was investigated. Cu-Ti alloys, which had good wettability and reactivity with $Al_{2}$O$_{3}$ ceramic, were examined for infiltration. Infiltration of the alloys was performed in vacuum at 1100.deg.C. The melt of Cu-50 at % Ti alloy was well penetrated through the porous $Al_{2}$O$_{3}$ coating and tightly sealed the pores, unbounded area and microcracks in the coating. The alloy melt in the pores reacted with $Al_{2}$O$_{3}$ ceramic to produce a suboxide phase, Cu$_{2}$Ti$_{4}$O. This composite layer which was composed of $Al_{2}$O$_{3}$ and Cu$_{2}$Ti$_{4}$O phase had good microstructure and wear and corrosion resistance. Additionally, microstructures at interfaces between coating layers were greatly improved owing to the effect of vacuum heat treating.

• Tribology and Lubricants
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• 제23권4호
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• pp.170-174
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• 2007

Wear and scuffing tests were conducted using friction and wear measurement of piston rings and cylinder blocks in low friction diesel engine. The frictional forces, wear amounts and cycles to scuffing in boundary lubricated sliding condition were measured using the reciprocating wear tester. The cylinder blocks were used as reciprocating specimens, and the piston rings with several coatings were used as fixed pin. Several coatings were used such as DLC, TiN, Cr-ceramic and TiAlN in order to improve the tribological characteristics. From the tests wear volume of piston ring surfaces applied various coatings were compared. During the tests coefficients of friction were monitored. Test results showed that DLC coatings showed good tribological properties. TiN and Cr-ceramic coated rings showed good wear resistance properties but produced high friction.

• 한국세라믹학회지
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• 제34권1호
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• pp.7-12
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• 1997

건조 및 다습한 대기의 무윤활 또는 액체 윤활, 미끄럼 속도 그리고 온도 등 여러 조건 하에서 SiC-강 미끄럼 시 SiC가 나타내는 마모거동에 대하여 조사하였다. 또 SiC의 제조공정이 SiC 마모에 미치는 영향도 미끄럼 속도를 달리하면서 고찰하였다. 무윤활 미끄럼 시 대기 습도는 일종의 윤활제 역할을 하며, 특히 대기가 매우 건조한 조건 하에서 미끄럼 속도는 마모에 큰 영향을 미친다. 그리고 SiC의 제조공정 및 재료표면의 거칠기는 미끄럼 속도의 크기여하에 따라 상이한 마모거동을 초래한다. 특히 온도는 마모를 심화시키는 요인이어서 윤활 미끄럼 조건 하에서도 마모를 크게 가속한다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1992년도 제15회 학술강연회초록집
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• pp.1-20
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• 1992

1. Ceramics as engineering Materials Ceramic \ulcorner :'material based on inorganic non-metallic compounds' Oxygen, Carbon, Nitrogen with metal (Al, Si) -cheap, plentiful and widespread element in the Earth -dirt: ceramic

• 한국세라믹학회지
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• 제33권5호
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• pp.479-484
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• 1996

The tribological properties of ceramics are very important in the application to engineering ceramic parts such as mechanical seal slurry valve disc and so on. In this study the effect of graphite addition on the mechanical and tribological properties of RBSC/graphite composites were investigated. The composites were prepared by adding graphite powder to the mixture of SiC powder metallic siliconcarbon black and alumina. Bending strength water absorption friction coefficient the amount of worn out material at a certain time and maximum surface roughness(Rmax) of the prepared composites were measured and crystalline phases were examined with XRD. The composite containing 5 vol% graphite powder showed improved bending strength due to high green density and decreased friction coefficient and wear resistance. The friction coefficient and the wear resistance of the composite were increased by adding graphite powder up to 10 vol% They decreased however as increasing the amount of graphite powder more that 10vol% There was no linear relationship between the tribological properties and bending strength of the composites.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.593-598
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• 2003

Ceramic plates containing many micro-holes are used in diverse applications such as MCP (Microchannel Plate). catalytic converters, filters, electrical insulators in integrated circuits, and so on. One of the efficient methods for machining many holes in ceramic plates is wet drilling of ceramic green bodies followed by sintering them. Since the strength of ceramic green bodies is much lower than the strength of sintered ceramic plate, ceramic green bodies can be drilled with high feed rate. The axial force during micro-drilling of ceramic green bodies increases rapidly at high feed rate, which induces the crack in workpiece. Therefore, the tool lift of micro-drill with respect to feed rate may be determined by the predicting increase of axial force. In this work, the axial force during micro-drilling was calculated using the chip flow model on the micro-drill tip. from which the tool life of diamond abrasive micro-drill during micro-drilling of ceramic green bodies was calculated.

• The Korean Journal of Ceramics
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• 제5권2호
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• pp.155-161
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• 1999

The tribological behaviour of monolithic SiC as well as SiC-TiC and SiC-TiC-$TiB_2$ particulate composite materials has been investigated in unlubricated oscillating sliding tests against $Al_2O_3$ at temperature in the range from room temperature up to $600^{\circ}C$. At temperatures below $600^{\circ}C$ the wear rate of the systems with the composite materials was up to 20 times lower than the wear of the $Al_2O_3$/SiC system and was dominated by the oxidation of the titanium phases. At $600^{\circ}C$ the oxidation rate of the TiC and -TEX>$TiB_2$ grains becomes predominant resulting in an enhanced wear rate of the composite rate of the TiC and TiB2 grains becomes predominant resulting in an enhanced wear rate of the composite materials. The coefficient of friction shows similar values for all materials of investigation, increasing from 0.25…0.3 at room temperature to 0.7…0.8 $600^{\circ}C$. The wear of the $Al_2O_3$/SiC system is mainly abrasive at temperatures above room temperature and is characterised by an enhanced wear of the alumina ball at $600^{\circ}C$.