Papers by Keyword: Sliding

Abstract: The present work aims to experimentally investigate the effect of Kevlar fiber hybridization on dry sliding friction and wear behaviour of bamboo fiber reinforced laminated epoxy composite. Monolithic bamboo laminated composite and different bamboo/Kevlar inter-ply laminated hybrid composites with variation in number of both the laminas were developed in house by hand layup technique. Pin-on-disc experiment was employed to determine its tribological performance. The wear mass loss, specific wear rate and co-efficient of friction of the developed composites, when slide against a rotating disc, were determined and analyzed. The wear mechanisms were studied from the microstructure. From the results, it is observed that, wear loss and co-efficient of friction values were increased with the increase in number of Kevlar laminas.

Abstract: The effect of surface topography in combination with chemical composition on hydrophobicity and static coefficient-of-friction between steel and ice was studied. Polished stainless steel blocks were etched to introduce a roughness, and further treated with octadecanethiol. Carbon rich inclusions, identified by energy-dispersive X-ray spectroscopy, and scratches acted as the exposure centers to promote etching. Due to heterogeneities in steel, rounded cavities and parallel troughs were found on the surface after etching. Etched blocks with a lowered surface energy were studied under various ambient conditions to determine the influence of ice temperature and humidity on the static coefficient-of-friction. Blocks modified with octadecanethiol showed improved hydrophobicity. Warmer ice conditions led to a lower friction, regardless of the surface modification.

Abstract: This paper proposes a roller burnishing method that controls the sliding direction of the burnishing tool on the surface of cylindrical workpiece. In this study, the sliding direction was set by inclining the axis of the burnishing tool with respect to the axis of the workpiece and by actively rotating the roller of the burnishing tool. The workpiece was a cylindrical aluminum alloy bar, which was rotated in a bench lathe. The burnished surfaces at several sliding angles between 15º and 90º were evaluated. The sliding direction, which is set according to a theoretical equation, was experimentally obtained for every sliding angle in the range of 15-90º with respect to the circumferential direction of the workpiece. The sectional profile was flattened and surface roughness was decreased with increasing sliding angle. As a result, the burnished surfaces obtained in this work were superior to those obtained in an earlier study by the authors, in which the burnishing tool was not actively rotated.

Abstract: This article studies the mechanism of work hardening of austenitic high manganese steel alloyed with chromium and vanadium. The steel was annealed at 650°C before austenitizing at 1100°C, and then was quenched with water. We have observed that after the heat treatment, the size of austenite grain was small (1,950μm² - level 6). The hardness of the steel was 223HB and the toughness was 115J/cm². After impact loading, there was no martensite but twinning and sliding in the microstructure of the steel. The nano austenite was found in the microstructure. The steel was also hardened by small austenite grain and the carbide particles were finely dispersed in the microstructure.

Abstract: This paper discusses a finite element analysis of cylinder on flat contact configuration subjected to constant normal load and reciprocating tangential displacement with linear kinematic hardening models based on bi-modal Ti-6Al-4V cyclic stress-strain curves. The predicted evolution of plastic deformation such as the equivalent plastic strain, tangential plastic strain and shear plastic strain distributions on the contact region has been studied along with its respective predicted stress distributions. The effect of applied forward and backward sliding displacement movements on predicted stress and strain distributions have also been looked at. It is found that the stress distributions predicted for kinematic hardening model is similar for forward and backward movements while the predicted plastic strain distribution is increasing with reciprocating sliding movement. The predicted value keep increasing when it moves forward, backward and finally moves forward again. This is due to large strain effect of the model and its dependant on the displacement movement amount.

Abstract: Strain-induced folds on the lateral faces of copper monocrystals generated in compression and sliding tests have been studied using SEM and OM techniques. It has been established that these folds form at different structural scale levels by similar mechanisms related basically to distortion of faces in the vicinity of their end faces during the so-called "lip" formation. Under compression folds have also been formed on the lateral areas bended and on the strain domain boundaries.Keywords: single crystal, wrinkling, folding fragmentation, texture, sliding.

Abstract: The effect of second particles on the grain boundary deformation in 304 type austenitic stainless steel was studied. Flat tensile samples with marker scratches on the surface were strained at slow rate at intermediate temperatures (300-500 °C) at ambient pressure. It seems that the sensitized material decreased creep rate and needed more stress to generate deformation of grain boundary, suggesting Cr carbides decreased the grain boundary sliding. Thus, the resistance to SCC crack propagation could be improved. The Charpy tests suggested that sensitized material had lower fracture toughness; this was due to the GB carbides that acted as nucleation sites for brittle fracture. Characterizations of the tensile samples were carried out using a secondary electron microscope in order to understand whether second phases can affect the creep behavior and grain boundary sliding.

Abstract: Study shows that gold can resist the formation of insulating oxide films that could interfere with reliable contact operation. So the gold coatings are often used in the contacts of separable electrical connectors and other devices. In this article, the corrosion test method is carried to show the porosity of specimens in gold coatings and the testing procedure is based on JIS standards. In addition to corrosion atmosphere, there is a sliding between the contact surfaces of the connector, which would affect the resistance of the connector contact materials. This paper studies the complicated effects of the corrosion environment and sliding on the dynamic resistance of the contacts materials of Au plated. Series of inspections and analytical research methods are introduced in this article. The surface morphology of specimens after corrosion test is observed by stereoscopic microscope and scanning electron microscope (SEM). Chemical constitution was examined by X-ray energy spectrum. The contact resistances were measured by four-point method. The experiment results show that after corrosion test by SO₂ with JIS corrosion test, the corrosion products appear islands-like spots on gold plating surface after corrosion test. The corrosion degree of gold plating specimens is decreased with the increase of the thickness of gold coatings. The results show that corrosion environment and sliding has a more complex and significant impact on the performance of the contact materials than single-factors, and the tests are closer to the real working environment.

Abstract: In the current study, wear and frictional performances of different metals are investigated under different operating parameters against stainless steel counterface under dry contact conditions. The experiments performed using block on ring machine. Microscopy was used to examine the damage features on the worn surface and categorize the wear mechanism. Thermal imager was used to understand the thermal loading in the interface during the rubbing process. The results revealed that the operating parameters influence the wear and frictional behaviour of all the metals. Brass metal exhibited better wear and frictional behaviour compared to others. Three different wear mechanisms were observed, i.e. two body abrasion (Brass), three body abrasion (Aluminium) and adhesive (Mild Steel).

Abstract: Copper single crystals grown according to the Bridgman method and having their axes [] or [11 aligned with the normal load axis were processed by dry sliding. As shown, sliding-induced severe plastic deformation occurred in the subsurface of single crystals and caused formation of a lip by mechanism of texture formation. The SEM structure of this lip was found to be composed of fragments with their shapes dependent on the single crystal orientation with respect to normal load and friction force.