• 열처리공학회지
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• 제15권2호
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• pp.82-92
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• 2002

In the present investigation wear behavior of the 6061AI composites reinforced with 5, 10, 20% SiC particles for dry sliding against a SM45C counterface was studied as a function of load and sliding velocity. Sliding wear tests were conducted at two loads(19.6 and 49N) and three sliding velocities(0.2, 1 and 2 m/sec) at constant sliding distance of 4000 m using pin-on-disk machine under room temperature. Presence of SiC reinforcement particles in the composites has displayed a transition from mild to severe wear at relatively higher applied load and sliding velocity compare to that of the matrix metal. As the volume fraction of SiC particles increased, the transition moved to a more severe wear conditions. Eventually, mild wear prevailed at a most severe wear conditions in this study, that was 49N load and 2 m/sec sliding velocity in 20% SiC particle/6061AI composite.

• Tribology and Lubricants
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• 제31권3호
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• pp.125-140
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• 2015

In this paper, we present the results of the wear analysis of journal bearings on a stripped-down single-cylinder engine during start-up and coast-down by motoring. We calculate journal bearing wear by using a modified specific wear rate considering the fractional film defect coefficient and load-sharing ratio for the asperity portion of a mixed elastohydrodynamic lubrication (EHL) regime coupled with previously presented graphical data of experimental lifetime linear wear in radial journal bearings. Based on the calculated wear depth, we obtain a new oil film thickness for every crank angle. By examination of the oil film thickness, we determine whether the oil film thickness at the wear scar region is in a mixed lubrication regime by comparing dimensionless oil film thickness, h/σ, to 3.0 at every crank angle. We present the lift-off speed and the crank angles involved with the wear calculation for bearings #1 and #2. The dimensionless oil film thickness, h/σ, illustrates whether the lubrication region between the two surfaces is still within the bounds of the mixed lubrication regime after scarring of the surface by wear. In addition, we present in tables the asperity contact pressure, the real minimum film thickness at the wear scar region, the modified specific wear rate, and the wear angle, α, for bearings #1 & #2. To show the real shape of the oil film at wear scar region, we depict the actual oil film thickness in graphs. We also tabulated the ranges of bearing angles related with wear scar. We present the wear volume for bearings #1 and #2 after one turn-on and turn-off of the engine ignition switch for five kinds of equivalent surface roughness. We show that the accumulated wear volume after a single turn-on and turn-off of an ignition switch normally increases with increasing surface roughness, with a few exceptions.

• Tribology and Lubricants
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• 제31권3호
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• pp.109-124
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• 2015

This paper presents a wear analysis procedure for the journal bearings on a stripped-down single-cylinder engine during start-up and coast-down by motoring. A journal bearing is in the mixed elastohydrodynamic (EHL) lubrication region when the shaft speed is less than the corresponding lift-off speed. Below the lift-off speed, a wear scar can form on bearing surfaces. In part 1 of this paper, we develop the appropriate formulations and the calculation procedure for the analysis. Specifically, we formulate an equation for modified film thickness in a journal bearing considering the additional wear volume. In order to obtain the modified specific wear rate induced by the modified Archard’s wear coefficient, we utilized the extended non-dimensional diagram for the specific wear rate, k, the fractional film defect coefficient, Ψ and the asperity load sharing factor, γ₂. This asperity load sharing factor is newly calculated by setting the Zhao-Maietta-Chang (ZMC) asperity contact pressure equation coupled with the central film thickness equation derived by using the ZMC asperity contact model equal to the modified central contact pressure derived by using the central (or maximum) contact pressure at the dry rough line-contact configuration. We can use the procedure introduced in this paper to determine the lifetime (or longterm) linear wear in radial journal bearings that is a result of repeated stop-start cycles.

• 자원리싸이클링
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• 제14권1호
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• pp.39-46
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• 2005

본 연구에서는 고상폐기물(소각재) 처리를 위해 중간 전극 (IEI, Inter-Electrode Insert)이 있는 button 형태의 고형 체형 고출력 토치를 개발하였고 폐기물처리 플라즈마설비에 적용하여 운전특성을 얻었다. 본 연구의 토치 실험 결과 비이송형 모드에서는 가스량의 증가에 따라 전압이 증가하였고, 이송형 모드에서는 가스량 변화에는 영향이 없었으나 토치와 바닥면과의 거리, 슬래그의 성분 그리고 용융 슬래그의 체적에 따라 전압의 변화가 발생하였다. 특히 아크전압이 슬래그내의 total Fe 함량이 10% 내외에서 안정적으로 유지되었으며, 전기전도도 계산결과 0.05~0.25${\Omega}^{-1}cm^{-1}$ 범위로 나타났다. 본 연구의 토치 효율은 75~85%로 나타났으며, 마모율은 2${\times}10^{-6}~6{\times}10^{-6}$ kg/s의 범위로 나타났다.

• 비파괴검사학회지
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• 제32권1호
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• pp.64-70
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• 2012

국내 원자력발전소 증기발생기 전열관의 건전성을 평가하기 위해서 수행되는 와전류검사의 탐촉자는 주로 두가지 종류가 사용한다. 첫 번째 와전류탐촉자는 마모와 같은 체적성 결함을 검사하기 위해 사용되는 보빈탐촉자이다. 두 번째 와전류탐촉자는 균열과 같은 비체적성 결함을 검사하기 위한 회전형 탐촉자이다. 와전류탐촉자는 검사 계통의 핵심적인 부분으로서 특정 절차서에 따라 평가가 이루어질 때 대상 시험체의 합부를 결정하는 자료를 제공하게 된다. 또한, 수집된 와전류신호의 품질은 사용되는 탐촉자의 설계특성, 기하학적 형태, 운전주파수에 따라 결정되고, 검사 결과에 미치는 영향이 크기 때문에 와전류검사 탐촉자의 선정은 특히 중요하다. 본 연구에서는 차동형 보빈탐촉자의 코일 권선 수의 변화가 탐촉자의 전기적 특성에 미치는 영향을 분석하였다. 이 결과를 이용하여 원전 증기발생기 전열관 와전류검사 보빈탐촉자를 설계하였다. 연구 결과 코일 권선 수의 변화는 전열관 형상 및 재질에 따른 검사주파수 선정에 크게 영향이 미침을 알 수 있다. 따라서 본 연구 결과를 통하여 원전 증기발생기 전열관 와전류검사 보빈탐촉자의 설계시 더욱 정밀한 코일 권선 수 설정에 토대를 구축하였다.

• Journal of Welding and Joining
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• 제15권6호
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• pp.96-104
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• 1997

The present study was aimed to correlate the microstructure and the hardness as well as the wear resistance of the metal-ceramic particulated composite layer on the pure Al plate. The composite layers were constructed by the addition of TiC particles on the surface of Al-Cu alloyed layers by PTA overlaying process. Initially, the Al-Cu alloyed layers were achieved by the deposition of Al-(25 ~ 48%) Cu alloys on the pure Al plate by TIG process. It was revealed that TiC particles were uniformly dispersed without any reaction with matrix in the composite layer. The volume fraction of TiC particles (TiC V F) increased from 12% to 55% with increasing the number of pass of composite layer. Hardnesses of (Al-48%Cu + TiC (3&4layers)) composite layer were Hv450 and Hv560, respectively, due to the increase of TiC V/F. Hardnesses of (Al-Cu + TiC) composite layers decreased gradually with insreasing temperature from 100$^{\circ}$C to 400$^{\circ}$C, and hardnesses at 400$^{\circ}$C were then reached to 1/5 - 1/10 of room temperature hardness depending on the construction of composite layers. The Specific wear of (Al + Tic) layer and Al-48%Cu alloyed layer decreased to 1/10 of the of pure Al, while the specific wear of (Al-48%Cu + TiC (4 layers)) composite layer exhibited 1/15 of that of steel such as SS400 and STS304.