• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.253-254
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• 2002

Based on 3-D surface morphology measurements of C.G. irons, the fractal analyses were made on relationship between dry sliding surface morphology and the fractal dimension. It is revealed that the values of fractal dimensions ($D_f$) of sliding surfaces are in the range between 1-2, which are closely related to the surface morphologies. With the increase in depths of grooves or pits, the $D_f$ values increase. At the same time, the increases in densities of the grooves also cause the $D_f$ values to increase. At last, relationship among $D_f$ and friction coefficient as well as wear rate is discussed.

• Transactions of Materials Processing
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• v.19 no.6
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• pp.357-362
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• 2010

Dry sliding wear behavior of pure Fe and Cu which have BCC and FCC crystal structure, respectively, was investigated. The wear characteristics of the pure metals with different crystal structure were compared. Dry sliding wear tests were carried out using a pin-on-disk wear tester at various loads under the constant sliding speed condition of 0.15 m/s against a silica ball at room temperature. Sliding distance was fixed as 600 m for all wear tests. Wear rate of a specimen was calculated by dividing the weight loss of the specimen after the test by the specific gravity and sliding distance. Worn surfaces and wear debris were analyzed by SEM. The wear of both pure Fe and Cu proceeded with surface deformation, resulting in similar wear rates despite of their structure difference under the current test conditions. Wear rates of both metals were low if the surface deformation due to wear forms thick surface-deformation layer that is strain hardened beneath the wearing surface. The pure Cu specimens showed a lot of oxides on the worn surface when tested at low loads less than 5 N, which resulted in very low wear rate.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3404-3412
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• 1994

The present study was undertaken to investigate the dry wear process and wear mechanism of the alumina ceramics in the purity variation which are used for the mechanical seal, roll, liner and dies. The wear test was carried out under different experimental condition using the wear testing device and in which the annular surface rubbed on dry sliding condition various sliding speed, contact pressure and sliding distance. In case of alumina purity 95%, there was speed range which wear loss increased rapidly owing to enlargement of heat impact force and temperature rise of wear surface. According as the alumina purity increased, wear loss decreased but alumina purity 85% with much void and defect had the most wear loss than any other alumina purity. The friction coefficient of sliding initial stage of wear curves has a large value but according to increase of sliding distance, it decreased owing to drop of the shear strength of wear surfaces.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.540-547
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• 2001

This study has evaluated the wear behavior of PTA (Plasma Transferred Arc) Inconel 625 and Stellite 6 overlays on Nimonic 80A substrate. Nimonic 80A alloy was also included for comparison. In order to evaluate the wear performance, three-body abrasive wear test and pin-on-disk dry sliding wear test were performed. Microstructural development during the solidification of deposits is also discussed. Wear test results show that the wear rate of Stellite 6 deposit is lower than that of Inconel 625 deposit and Nimonic 80A. The sliding wear resistance of overlay deposits follows a similar trend to the abrasive wear resistance, but for Nimonic 80A. The main wear mechanisms were abrasive wear for Inconel 625 deposit, adhesive wear and delamination for Stellite 6 deposit in pin-on-disk dry sliding wear test and ploughing in three-body abrasive wear test. Cross sectional examinations of the worn surface of pin specimens after pin-on-disk dry sliding wear test implies that the plastic deformation near worn surface has occurred during the wear testing.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.149-152
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• 2006

Dry sliding wear behavior of low carbon dual phase steel, of which microstructure consists of hard martensite in a ductile ferrite matrix, has been investigated. The wear characteristics of the dual phase steel was compared with that of a plain carbon steel which was normalized at $950^{\circ}C$ for 30min and then air-cooled. Dry sliding wear tests were carried out using a pin-on-disk type tester at various loads of 1N to 10N under a constant sliding speed condition of 0.2m/sec against an AISI 52100 bearing steel ball at room temperature. The sliding distance was fixed as 1000m for all wear tests. The wear rate was calculated by dividing the weight loss measured to the accuracy of $10^{-5}g$ by the specific gravity and sliding distance. The worn surfaces and wear debris were analyzed by SEM, EDS and a profilomter. Micro vickers hardness values of the cross section of worn surface were measured to analyze strain hardening behavior underneath the wearing surfaces. The were rate of the dual phase steel was lower than the plain carbon steel. Oxidation on the sliding surface and strain hardening were attributed for the higher wear resistance of the dual phase steel.

• International Journal of Automotive Technology
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• v.5 no.2
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• pp.123-133
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• 2004

This paper describes a robust and fast wheel slip tracking control using a moving sliding surface technique. A traction control system (TCS) is the active safety system used to prevent the wheel slipping and thus improve acceleration performance, stability and steerability on slippery roads through the engine torque and/or brake torque control. This paper presents a wheel slip control for TCS through the engine torque control. The proposed controller can track a reference input wheel slip in a predetermined time. The design strategy investigated is based on a moving sliding surface that only contains the error between the reference input wheel slip and the actual wheel slip. The used moving sliding mode was originally designed to ensure that the states remain on a sliding surface, thereby achieving robustness and eliminating chattering. The improved robustness in driving is important due to changes, such as from dry road to wet road or vice versa which always happen in working conditions. Simulations are performed to demonstrate the effectiveness of the proposed moving sliding mode controller.

• Tribology and Lubricants
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• v.21 no.3
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• pp.130-135
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• 2005

Dry sliding wear resistance of DLC coated silicon disk with different surface roughness has been evaluated using a ball-on-disk sliding tester. It was found that the transfer layer formed on steel ball produced a low friction regime and the formation of transfer layer was more active with increasing the substrate surface roughness. Wear life of DLC coating was increased as increasing the real area of contact.

• Advances in materials Research
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• v.4 no.3
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• pp.165-178
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• 2015

Friction coefficient of epoxy metal matrix composites were investigated. The main objective was to increase the friction coefficient through rubber sole sliding against the epoxy floor coating providing appropriate level of resistance. This was to avoid the excessive movement and slip accidents. Epoxy metal matrix composites were reinforced by different copper wire diameters. The epoxy metal matrix composites were experimentally conducted at different conditions namely dry, water and detergent wetted sliding, were the friction coefficient increased as the number of wires increased. When the wires were closer to the sliding surface, the friction coefficient was found to increase. The friction coefficient was found to increase with the increase of the copper wire diameter in epoxy metal matrix composites. This behavior was attributed to the fact that as the diameter and the number of wires increased, the intensity of the electric field, generated from electric static charge increased causing an adhesion increase between the two sliding surfaces. At water wetted sliding conditions, the effect of changing number of wires on friction coefficient was less than the effect of wire diameter. The presence of water and detergent on the sliding surfaces decreased friction coefficient compared to the dry sliding. When the surfaces were detergent wetted, the friction coefficient values were found to be lower than that observed when sliding in water or dry condition.

• Tribology and Lubricants
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• v.25 no.1
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• pp.66-72
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• 2009

Al-based composites reinforced with SiC particulate were fabricated using a thermal spray process, and dry sliding wear behavior of the composites was investigated. Pre-mixed Al and SiC powders were sprayed on an A16061 substrate by flame spraying, and dry sliding wear test were performed under various sliding speed and applied load conditions against ${Al_2}{O_3}$ ball. Wear behavior of the composites was studied by using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). And build-up mechanism of MML on the worn surface of the composites was examined. It was revealed that these MML was formed of debris from the contact surface of the composites and effected to wear behavior of the composites protecting the contact surface of the composites.

• Tribology and Lubricants
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• v.22 no.3
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• pp.137-143
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• 2006

The sliding contact interface of machine components such as bearings, gears frequently operates in lubrication at the inception of sliding failure under high loads, speed and slip. The surface temperature at the interface of bodies in a sliding contact is one of the most important factors influencing the behavior of machine components. Most surface failure in sliding contact region result from frictional heat generation. However, it is difficult to measure temperature rise experimentally. So the calculation of the surface temperature at a sliding contact interface has long been an interesting and important subject for tribologist. The surface temperature rise is related in contact pressure, sliding speed, material properties and lubrication thickness. Though roughness, load, ect all of the condition, are same, film thickness varies with velocity. In this study, surface temperature rise due to frictional heating in lubrication is calculated with various velocities. Surface film shearing and dry solid asperity contact are used to simulate the change of frictional heat in lubricated contact