• 열처리공학회지
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• 제16권6호
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• pp.335-340
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• 2003

To improve properties of wear resistance and anti-corrosion of the trivalent chromium platings, oxinitrocarbunsing and steam oxidation were conducted. Armophous trivalent Cr platings could be transformed to chromium carbides of high hardness, that showed low friction and wear rate. Even though micro-cracks were within as platings, superior anti-corrosion property was obtained by these treatments due to healing of cracks at the interface between the trivalent chromium platings and substrate.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.857-858
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• 2006

In order to clarify the wear resistance as cutting tools, the effect of oxygen addition on oxidation behavior of the ${\beta}-Si_3N_4$ ceramics with 5 mass% $Y_2O_3$ and 2 or 4 mass% $Al_2O_3$ was investigated by performing oxidation tests in air at $1300^{\circ}$ to $1400^{\circ}C$ and cutting performance tests. From test results, we could conclude that the mechanical properties of ${\beta}-Si_3N_4$ ceramics depending on oxygen introduction are much effective on cutting performance improvements of ${\beta}-Si_3N_4$ ceramics.

• 폴리머
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• 제25권1호
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• pp.133-141
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• 2001

산화억제제로 사용한 이규화 몰리브덴($MoSi_2$)의 함량에 따른 일방향 탄소/탄소 복합재료의 마찰 및 마모 특성에 관하여 대기상태 하에서 정속마찰시험기를 이용하여 측정하였다. 그 결과, 탄소/탄소 복합재료는 마찰온도 150~180${\circ}C$에서 급격한 마찰계수의 전이, 즉 normal wear 영역에서의 낮은 마찰계수(${\mu}$=0.15~0.2)에서 dusting wear 영역에서의 높은 마찰계수(${\mu}$=0.5~0.6)로의 전이를 나타내었다. 이렇게 마찰계수가 전이하는 온도범위의 존재는 탄소/탄소 복합재료로 만든 브레이크가 복합재료의 열적 특성에 큰 영향을 받는다는 것을 의미한다. 그리고 산화억제제인 $MoSi_2$를 가지는 탄소/탄소 복합재료는 이를 함유하지 않은 복합재료에 비해 약 1.5배 정도의 낮은 평균마찰계수 및 마모율을 나타내었으며, 특히 4 wt% $MoSi_2$ 함량을 가진 복합재료가 가장 큰 마모활성화 에너지 값을 나타내었다.

• Journal of Mechanical Science and Technology
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• 제16권9호
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• pp.1065-1071
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• 2002

The friction and wear behaviors of magnetron sputtered MoS$_2$ films were investigated through the use of a pin and disk type tester. The experiments were performed for two kinds of specimens (ground (Ra 0.5 $\mu\textrm{m}$) and polished (Ra 0.01 $\mu\textrm{m}$) substrates) under the following operating condifions : linear sliding velocities in the range of 22～66 mm/s (3 types), normal loads varying from 9.8～29.4 N(3 types) and atmospheric conditions of air, medium and high vacuum (3types). Silicon nitride pin was used as the lower specimen and magnetron sputtered MoS$_2$ on bearing steel disk was used as the upper specimen. The results showed that low friction property of the MoS$_2$ films could be identified in high vacuum and the specific wear rate in air was much higher than that in medium and high vacuum due to severe oxidation. It was found that the main wear mechanism in air was oxidation whereas in high vacuum accumulation of plastic flow and adhesion, were the main causes of wear.

• Tribology and Lubricants
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• 제12권1호
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• pp.22-28
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• 1996

This study was undertaken to investigate the dry wear characteristics and mechanism of KP-4M steel for plastic molding against SKD 61 hardened by heat treatment. The wear test was carried out under different conditions such as sliding speed, contact pressure, sliding distance, with frictional tester of pin on disc type. The wear loss on variation of sliding speed was little in lower speed range below 0.5 m/sec and in higher speed range above 1.5 m/sec,'but wear loss was high in intermediate speed range. The critical sliding speed, which showed the maximum value of specific wear rate, became lower with increased contact pressure. Increasing the contact pressure, the critical sliding distance Lcr which the wear mechanism changes from severe wear to mild wear was increased due to the decrease of oxidation reaction velocity. Through this study we suggested a model of generation and elimination process of wear debris of KP-4M steel for plastic molding.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.844-847
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• 2002

This paper is to investigate the wear behavior of submerged-arc clad materials by the wear test with a ball-on-disk type wear testing machine in air. The specimens were clad with Stoody105 alloy wire on a carbon steel (SM45C) substrate by submerged-arc cladding process under different welding parameters. The wear behavior of the cladding through ball-en-disk test has been studied under the wear load from 5N to 16N and sliding speed from 8cm/s to 35cm/s. The weight of the specimen loss was measured. Scanning electron micrographs of the worn surface show a layer of oxide film formed on the worn surface. Oxidation wear mechanism controls the wear process. The spalling of the oxide is caused by the repeated rubbing fatigue mechanism.

• 한국정밀공학회지
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• 제20권1호
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• pp.179-186
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• 2003

This paper is to investigate the wear behavior of submerged-arc claddings by the wear test with a ball-on-disk type wear testing machine in air. The specimens were clad with Stoody105 alloy wire on a medium carbon steel (SM45C) substrate by submerged-arc cladding process under different welding parameters. The wear behavior of the cladding through ball-on-disk test has been studied under the wear load from 5 to 16 N and the sliding speed from 8 to 35 cm/s. The weight loss of the specimen was measured. Scanning electron micrographs of the worn surface show a layer of oxide film formed on the worn surface. Oxidation wear mechanism controls the wear process. The spatting of the oxide is caused by the repeated rubbing fatigue mechanism.

• Tribology and Lubricants
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• 제22권2호
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• pp.73-78
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• 2006

The surface modification of automobile parts is of great technological importance for the improvement of corrosion resistance, wear resistance, fatigue strength and so on. Recently, research on the development of the technology of surface modification substituting 6-balance chrome process has progressively been achieved in automobile parts. Although the innovation technology for the improvement of the corrosion-resisting and wear resistant properties through post oxidation after nitrocarburising process had attracted a great attention. For this, anodically potentiodynamic polarisation testing was carried out to corrosion resistance and friction and wear experiment according to applied load and sliding distance was carried out to evaluate the wear resistance of machine structural steel with nitrocarburising and non-nitrocarburising SM45C. The presumed wear volume was calculated with the image processing far evaluation of wear resistance of two materials. The results show that the nitrocarburising had a distinguished corrosion resistance and wear resistance than non-nitrocarburising.

• 한국표면공학회지
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• 제38권3호
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• pp.126-135
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• 2005

SKD 11 steel has been widely used for tools, metallic mold and die for press working because of its favorable mechanical properties such as high toughness and creep strength as well as excellent oxidation resistance. The ion nitrided tool steel containing Mo results in improvement of corrosion resistance, strength at high temperature and pitting resistance, especially in $Cl^-$ contained environment. But the Mo addition causes a disadvantage such as lower oxidation resistance at elevated temperature. In this study, several effects of ion-disadvantage on the oxidation characteristics for SKD 11 steel with various oxidation temperature were investigated. SKD 11 steels were manufactured by using vacuum furnace and solutionized for 1 hr at $1,050^{\circ}C$. Steel surface was ion nitrided at $500^{\circ}C$ for 1 hr and 5 hr by ion nitriding equipment. ion nitrided specimen were investigated by SEM, OM and hardness tester. Oxidation was carried out by using muffle furnace in air at $500^{\circ}C,\;700^{\circ}C\;and\;900^{\circ}C$ for 1hr, respectively. Oxidation behavior of the ion nitrided specimen was investigated by SEM, EDX and surface roughness tester. The conclusions of this study are as follows: It was found that plasma nitriding for 5 hr at $500^{\circ}C$, compared with ion nitriding for 1 hr at $500^{\circ}C$, had a thick nitrided layer and produced a layer with good wear, corrosion resistance and hardness as nitriding time increased. Nitrided SKD 11 alloy for 1hr showed that wear resistance and hardness decreased, whereas surface roughness increased, compared with nitrided SKD 11 alloy for 5 hr. The oxidation surface at $900^{\circ}C$ showed a good corrosion resistance.

• Tribology and Lubricants
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• 제9권1호
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• pp.38-44
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• 1993

The present study was undertaken to investigate the dry wear characteristics of die steel STD 11 for cold molding. The wear test was experimentally carried out under different conditions using a wear device, which was made in laboratory, and in which annular surfaces of wear testing specimens wear rubbed in dry sliding condition with varying the sliding speed, contact pressure, and sliding distance. The wear loss by variation of sliding speed was much in 0.3 m/sec and less in higher speed range above its sliding speed according to formation of the boundary lubrication film. The critical sliding speed with maximum value of the specific wear rate switched over to lower speed side according. as contact pressure increased. The critical sliding distance was increased with decrease in oxidation reaction velocity. The depth below subsurface showing maximum hardness (Hv) came out at the position, $60 \mu m$, of the maximum shear stress due to strain hardening.