• Tribology and Lubricants
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• v.13 no.4
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• pp.71-78
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• 1997

Wear is affected by numerous factors-contact load, sliding velocity and distance, friction coefficient, material properties and environmental conditions. Among these wear factors, surface hardness is one of very important factors to determine wear. But surface hardness is varied by work hardening during repeated sliding contact. In this reason wear rate is increased or decreased with varying surface hardness, and transition of wear mechanism is happened. In this study, the surface hardening by accumulating residual stress was analyzed by considering the repeated sliding Hertzian contact model. The results showed that surface hardness was increased with increasing contact load, friction coefficient and contact number. And the depth of hardening layer, plastic layer and elastic layer depended upon contact load and number, but they didn't depend upon friction coefficient. The predicted surface hardness was about 1.5-1.8 times as hard as the material.

• Tribology and Lubricants
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• v.15 no.1
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• pp.83-89
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• 1999

The fretting wear behaviour of Zircaloy-4 tube used as the fuel rod cladding in PWR nuclear power plants has been investigated at the different test environment, in light water and in air as a function of slip amplitude, normal load, test duration and frequency. Zircaloy-4 tubes were used for both of oscillating and stationary specimens. A fretting wear tester was designed to be suitable for this fretting test. The wear volume and specific wear rate of Zircaloy-4 tube in water was greater than those in air under various slip amplitude. Delaminates and surface cracks were observed at low slip amplitude and high load of fretting test in water, but the traces of adhesion and plowing were observed at and above 200 Um. The water accelerates the wear of Zircaloy-4 tube at lower slip amplitude in fretting.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.285-290
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• 2000

This paper was undertaken to do morphological analysis of wear debris for slipper-pad of hydrauric rotary acuator. The lubricating wear test was performed under different experimental conditions using the wear test device and wear specimens of the pin on disk type was rubbed in paraffinic base oil by three kinds of lubricating materials. varying applied load, sliding distance. The four shape parameters(50% volumetric diameter, aspect, roundness and reflectivity) are used showed that the four shape parameters of wear debris depend on a kind of the lubricating condition. It was capable of presuming wear volume for slipper-pad of hydrauric rotary acuator on driving time.

• Archives of Metallurgy and Materials
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• v.67 no.4
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• pp.1521-1524
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• 2022

Fe-Cr-B-based metamorphic alloy coating layers were manufactured by plasma spray with a Fe-Cr-B-Mo-Nb composition (hereinafter, M+) powder. The microstructure and wear properties of the coating layers were investigated and compared with a metamorphic alloy coating layer fabricated with commercial M material. XRD analysis revealed that the M and M+ coating layers were composed of α-Fe, (Cr, Fe)₂B, and some metallic glass phases. Wear test results showed that M+ coating layers had a superior wear resistance which had 1.48 times lower wear volume than M coating layers. Observations of the worn-out surfaces and cross-sections of the coating layers showed that M+ coating layer had relatively low oxides along the particle boundaries and it suppress a delamination behavior by the oxides.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.489-496
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• 1988

This paper is studied to know wear mechanism in variation of austempering temperature and holding time of austempered ductile cast iron against mating material SM45C hardened by heat treatment. The wear tests were carried out by rubbing the annular surface of two test pieces in dry sliding friction. The wear mechanism was investigated by scanning electron microscopy and the retained austenite volume fraction was investigated by X-ray diffractometer. The experimental results show that the wear characteristics depend largely on the oxidation of the testing materials which is influenced by the sliding velocity and distance. The retained austenite has a negative effect during frictional contact because it has increased severe wear by softened surface layer. It is shown experimentally that hard metals have lower frictional resistance and hence the resistance to adhesion is increased due to stronger interatomic linking bonds and increase in the surface energy.

• Tribology and Lubricants
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• v.38 no.6
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• pp.227-234
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• 2022

Recently, the demand for improving energy efficiency has rapidly increased because of the growing concerns over environmental issues. In this work, the tribo-test and simulation for the initial wear and lubrication performance were performed for the piston pin in the small end system of the connecting rod of a marine engine, to obtain useful data for improving the efficiency of marine engine systems. In addition, a diamond-like carbon (DLC) coating was applied to the piston pin to explore feasibility of eliminating the bush used in the system. The initial wear and lubrication characteristics between the uncoated piston pin and bush were compared with that between the DLC-coated piston pin and connecting rod in the tribo-test. The simulation for the wear and lubrication performance according to the wear progression was conducted based on the data obtained from the test. The wear characteristics were quantitatively assessed by the wear depth and wear volume, and the lubrication performance was characterized with the change of pressure and minimum oil film thickness with respect to the crank angle. It was found that the DLC-coated piston pin may provide better initial wear characteristics and lubrication performance. The results of this work may provide fundamental information for marine engines with improved efficiency.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.29-33
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• 2001

In the present study, AZ91Mg/$\textrm{Al}_2\textrm{O}_3$ short fiber+SiC particulates hybrid metal matrix composites(MMCs) were fabricated by squeeze casting method. Different particulate sizes of 45, 29 and $9\mu\textrm{m}$ were hybridized with 5% volume fraction to investigate the effect of SiC particulates size on microstructure, mechanical and thermal properties such as hardness, flexural strength, wear resistance and thermal expansion. Results show that the microstructure of the hybrid composites were quite satisfactory, namely revealing relatively uniform distribution of reinforcements. Some aggregation of SiC particulates caused by particle pushing was observed especially in the hybrid composites containing in fine particulates($9\mu\textrm{m}$). The hardness and flexural strength were improved by decreasing particulates size, whereas wear resistance improved by increasing particulates size because of large particulates restricting matrix wear from contacted stress. Regardless of particulates size, thermal expansion of composites was the same. This may be because the content of particulates was in all cases 5 volume fraction.1

• Journal of Environmental Science International
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• v.32 no.9
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• pp.627-634
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• 2023

Tire wear particles(TWPs), regarded as a microplastic, is generated in significant quantities each year and exist in various spaces and have a negative impact on the surrounding environment. Particularly, roadside environments fall within the direct influence of TWPs, necessitating proactive investigation for contamination management and response. Therefore, this study aimed to investigate the soil acidity and electrical conductivity(EC) and TWPs in the roadside soil of six sites based on traffic volume. The analysis revealed that the soil in all sites exhibited subacidity, and there were no significant differences in EC. Microscopic and FT-IR analysis revealed the presence of microscopic particles in soil samples that exhibited common visual characteristics of TWPs. In the road with the highest traffic volume, 48,300 TWPs were detected per unit area. Furthermore, a proportional relationship between traffic volume and TWPs particles was established. However, influences other than traffic volume on TWPs particle count within the soil were observed. Therefore, for the management of TWPs contaminated roadside soil, a proactive response is necessary in areas with high traffic volumes. However, in order to effectively address the factors contributing to the generation and dispersion of TWPs, further research is required with a multidimensional approach.

• Carbon letters
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• v.12 no.4
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• pp.249-251
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• 2011

Carbon/epoxy woven composites are prominent wear-resistant materials due to the strength, stiffness, and thermal conductivity of carbon fabric. In this study, the effect of oilabsorption on the wear behaviors of carbon/epoxy woven composites was investigated. Wear tests were performed on dry and fully oil-absorbed carbon/epoxy woven composites. The worn surfaces of the test specimens were examined via scanning electron microscopy to investigate the wear mechanisms of oil-absorbed carbon/epoxy woven composites. It was found that the oil absorption rate was 0.14% when the carbon/epoxy woven composites were fully saturated. In addition, the wear properties of the carbon/epoxy woven composites were found to be affected by oilabsorption. Specifically, the friction coefficients of dry and oil-absorbed carbon/epoxy woven composites were 0.25-0.30 and 0.55-0.6, respectively. The wear loss of the oilabsorbed carbon/epoxy woven composites was $3.52{\times}10^{-2}\;cm^3$, while that of the dry carbon/epoxy woven composites was $3.52{\times}10^{-2}\;cm^3$. SEM results revealed that the higher friction coefficient and wear loss of the oil-absorbed carbon/epoxy woven composites can be attributed to the existence of broken and randomly dispersed fibers due to the weak adhesion forces between the carbon fibers and the epoxy matrix.

• KSTLE International Journal
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• v.3 no.1
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• pp.43-48
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• 2002

Dry sliding wear and friction test of CrN coaling on two types of aluminum alloy substrates,6061 Al and 7075 Al deposited by arc ion plating, was peformed with a ball-on-disk tribometer. The effects of normal Bead and the mechanical properties of substrate on the friction coefficient and wear-resistance of CrN coating were investigated. The worn surfaces were observed by SEM. The results show that surface micro-hardness of CrN- coated 7075 Al is higher than that of CrN-coated 6061 Al. With an increase in normal lead, wear volume increases, while the friction coefficient decreases. The friction coefficient of CrN-coated 6061 Al is higher than that of CrN-coated 7075 Al, while the wear-resistance of CrN-coated 6061 Al is lower than the CrN-coated 7075 Al's, which indicates that the substrate mechanical properties have strong inf1uences on the friction coefficient and wear of CrN coating. The main wear mechanism was fragments of CrN coating, which were caused by apparent plastic deformation of substrate during wear test.