• Tribology and Lubricants
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• 제13권2호
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• pp.82-88
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• 1997

This paper describes an empirical equation which can be used to predict the engine condition of supersonic aircraft. The equation, which is derived from the trend analysis of JOAP data, represents the concentration of Fe particles in the engine oil. The result of the trend analysis shows that the concentration of Fe particles is a function of running time of engine oil. Meanwhile the slope of Fe concentration is a function of running time of engine. Threfore, the empirical equation was derived as $w=a(t_e).t_o+b$. However, the equation could not enough to diagnose the damaged part of engine quantitatively. To make up for the weak points of the equation, qualitative analysis was carried out. For that purpose wear debris were collected from the abnormal engine and analyzed by EDS to detect the damaged parts of engine.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.105-108
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• 2005

Sliding wear mechanism of a high nitrogen austenitic 18Cr-18Mn-2Mo-0.9N steel has been investigated. Dry sliding wear tests of the steel were carried out at various loads of 1N-10N under a constant sliding speed condition of 0.15m/s against AISI 52100 bearing steel balls. Solution $(1050^{\circ}C)$ and isothermal aging $(900^{\circ}C)$ heat treatments were performed on the steel and the effect of the heat treatments on the wear were investigated. Wear rates of the solution-treated steel specimen remained low until 5N, and then increased abruptly at loads above 5N. The rates of isothermally aged specimens were low and increased gradually with the applied load. Worn surfaces, their cross sections, and wear debris of the steel specimens were examined with a scanning electron microscopy. Phases of the heat-treated specimen and the wear debris were identified using XRD. Phases transformed underneath the sliding track during the wear were investigated and analyzed using TEM. Effects of the phase transformation during the wear and $Cr_2N$ precipitates formed during the isothermal aging on the wear of the austenitic steel were discussed.

• 한국재료학회지
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• 제15권12호
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• pp.824-828
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• 2005

In this study the effect of the content of $TiB_2$ on wear properties was investigated. $Cu-TiB_2$ composites have been fabricated by hot extrusion. Sliding wear tests were peformed by a pin-on-disk type wear test machine under dry condition and loads varied with from 20N to 80N at sliding speed 3.5Hz. The test results showed that the wear losses and the friction coefficients decreased with increasing $Cu-TiB_2$ volume fraction and increasing the size of $Cu-TiB_2$ particle. Wear property of $10{\mu}m,\;5 vol\%\; TiB_2$ specimen was excellent all of the wear specimens. It is thought that the increase of plastic flow resistivity due to uniform distribution of $10{\mu}m,\;5 vol\%\; TiB_2$ wear specimen would improve wear property. The worn surface and wear debris were examined by optical microscope and scanning electron microscope.

• 소성∙가공
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• 제15권2호
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• pp.112-117
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• 2006

Sliding wear mechanism of a high nitrogen austenitic 18Cr-18Mn-2Mo-0.9N steel has been investigated. Dry sliding wear tests of the steel were carried out at various loads of IN-10N under a constant sliding speed condition of 0.15m/s against AISI 52100 bearing steel balls. Solution ($1050^{\circ}C$) and isothermal aging ($900^{\circ}C$) heat treatments were performed on the steel and the effect of the heat treatments on the wear was investigated. Wear rates of the solution-treated steel specimen remained low until 5N load, and then increased abruptly at loads above 5N. The rates of isothermally aged specimens were low and increased gradually with the applied load. Worn surfaces, their cross sections, and wear debris of the steel specimens were examined with a scanning electron microscopy. Phases of the heat-treated specimen and the wear debris were identified using XRD. The transformed phase underneath a sliding track was investigated and analyzed using a TEM. Effects of the phase transformation during the wear and $Cr_{2}N$ precipitates formed during the isothermal aging on the wear of the austenitic steel were discussed.

• 한국재료학회지
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• 제16권8호
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• pp.511-515
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• 2006

The dispersion hardened $Cu-TiB_2$ composites are a promising candidate for applications as electrical contact materials. The $Cu-TiB_2$ composites for electrical contact materials can reduce material cost and resource consumption caused by wear, due to their good mechanical and electrical properties. In this study, we investigated the wear phenomenon for $Cu-TiB_2$ composites fabricated with hot extrusion, by varying particle sizes and volume fractions of $TiB_2$. The wear tests were performed under the dry sliding condition with a fixed total sliding distance of 40 m. The contact loads at a constant speed of 3.5 Hz were 20, 40, 60, and 80 N. The friction coefficients and wear losses were measured during wear tests. Worn surfaces and wear debris after wear tests were investigated using the scanning electron microscope and the optical microscope. The microstructures of interface between Cu matrix and $TiB_2$ particle before and after wear tests were studied by the transmission electron microscope.

• 한국주조공학회지
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• 제24권6호
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• pp.323-330
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• 2004

This study aims to investigate on the effects of the microstructures on the wear characteristics of the different grey cast iron(GC) and spheroidal ductile cast iron(DCI). Wear test using wear tester of pin-on-disc type was carried out under the conditions of load 47.2N , velocity 0.2m/s, distance 4000m. At the GC, Wear rates depend on graphite type and oxide layer formed at wear surface. Weak rosette graphites are easily broken and formed wear debris over 30 ${\mu}m$. This wear debris occurs scuffing at wear surface. As a result of surface deformation, Narrow regions of the matrix between the graphite flakes and the contact surface lead to the failure of the necks. Wear rate for the DCI depended on hardness of matrix more than size of graphite.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제27회 춘계학술대회
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• pp.180-189
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• 1998

This paper was undertaken to do shape analysis of wear debris on oiliness agent and extreme pressure agent. The lubricating wear test was performed under different experimental conditions using the wear test device was made in our laboratory and were- specimens of the pin on disk type was rubbed in paraffine series base oil by materials, varying applied load, sliding distance, oil additives such as stearine acid, DBDS, TCP. The four shape parameters (50% volumetric diameter, aspect, roundness and reflectivity) on a kind of the additives are different on applied load and sliding distance and Its are affected by absorbed film and reaction film. DBDS and TCP have a role of extreme pressure agent but a role of absorbed film of stearic acid decrease in high load. The maximum wear volume on applied load be in existence in three kinds of the specimens because of reaction characteristics of the additives.

• 한국정밀공학회지
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• 제27권10호
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• pp.45-51
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• 2010

Electrical discharge drilling (ED-drilling) is a widespread machining method used to bore small holes with a high aspect ratio. This paper presents additional methods by which ED-drilling can improve machining speed, tool wear, and machined surface quality. Firstly, for high machining speed, and low tool wear, a new-type electrode that was ground on one side or both sides of the cylindrical electrodes was suggested to expel debris. The debris which is generated during the machining process can cause sludge deposition and secondary discharge problems: major reasons to decrease machining speed. This new-type electrode also reduced tool wear that was due to the decrease of unstable discharge in a machining gap by helping to expel waste water and debris from the gap. Secondly, to improve the machined surface roughness, an electrolyzation process was included after drilling. This process made the machined surface smooth by means of an electrochemical reaction between an electrode and a workpiece. In this study, the machining speed, electrode wear, and surface roughness were improved by the newtype electrode and the electrolytic process.

• Elastomers and Composites
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• 제55권2호
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• pp.108-113
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• 2020

Wear particles of the model tread compounds for bus and truck tires were made using a laboratory abrasion tester and characterized based on their size distributions, shapes, and crosslink densities. The influence of the carbon black contents and rubber compositions (NR= 100 and NR/BR= 80/20) on the production of wear particles was investigated. The wear particles were separated according to size using a sieve shaker. The shape properties of the wear particles were analyzed using an image analyzer and scanning electron microscopy (SEM). Their shapes were observed as tiny stick cookies or sausages with bumpy surfaces. The particle size distribution tended to be smaller with increasing carbon black content. Moreover, the particle size distributions of the NR = 100 samples were larger than that of the NR/BR blend samples. There were different filaments in the wear particles. The filament diameters tended to be thinner with increasing carbon black content. The crosslink density increased with increasing carbon black content, and the crosslink densities of the NR= 100 samples were lower than those of the NR/BR blend ones. The particle size distribution tended to be smaller with increasing crosslink density. Based on the experimental results, the wear particles can be produced by detaching debris from the main body through repetitive strain and recovery.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.313-323
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• 2003

The sliding wear behaviors of Zircaloy-4 nuclear fuel rod were investigated using two support springs with convex and concave shapes in room temperature air and water. The main focus is to compare the wear behavior of various test variables such as slip amplitude, environment, contact contours with different spring shape and a number of cycles. The results indicated that wear volume and maximum wear depth increased with slip amplitude in both air and water, but their trends tended to change according to the spring shapes and test environments. In air condition, the wear volume was controlled by wear debris behavior generated on worn surface. As a result, final wear volume and maximum wear depth decreased if a ratio of protruded wear volume to worn area $(D_p)$ would be saturated to specific value. This is because wear particle layer could accommodate large strain by accumulating and transforming wear particle layer. However, in water condition, metal-to metal contact was more dominant and wear volume was greatly affected by changed mechanical behavior between contact surfaces since wear debris should be generated after repeated plastic deformation and fracture. After wear test, worn surfaces were examined using optical microscope and SEM and details of wear mechanism were discussed using a ratio of wear volume to worn area $(D_e)$ at each test condition.