Current Issue : October - December Volume : 2016 Issue Number : 4 Articles : 6 Articles
Anovel ceramic composite inward gradient distribution layer has been developed.Thelayer is a lubricating layer inwhich soft-metal\nlubricants are compounded into the ceramic matrix by high frequency induction infiltrating method. The design of the layer and its\nlubricating mechanism are investigated in the paper. The results show that the property of the layer greatly depends on the wetting\nangle of the soft-metal lubricants on the matrix and the proportion of Ag, Cu, Sn, and Pb as well as the infiltrating parameters.\nBased on a lot of experiments, a novel inward gradient layer with Pb28Sn19Ag6Cu has been developed. The layer has an excellent\nlubricating property (friction coefficient about 0.2âË?¼0.3 at 600âË?Ë?C). The research reveals the lubricating mechanism, observing the\nphenomenon that the soft-metal in the matrix diffuses out of the frictional surface, and measures the lubricating film thickness as\nabout 20 ...
A tartrate nickel plating bath has been used to prepare nickel- tungsten (Ni-W) dispersed PTFE\ncomposite coatings with four different PTFE contents (0, 4, 8 and 20 gl-1). The coatings are\ncharacterized using of Field-Emission Scanning Electron Microscopy (SEM), Energy Dispersive Xray\nAnalysis (EDAX) and X-ray Diffractrometry (XRD). XRD results indicate that the PTFE particle\nchanged the surface texture significantly. The nano tribological behavior of the nano composite\ncoating was estimated by contact mode of AFM. Electrochemical performance of the nanocomposite\ndepositions was evaluated using potentiodynamic polarization and electrochemical impedance\nspectroscopy (EIS). The results show that the Ni-W/PTFE nanocomposite films exhibit better\nelectrochemical and tribological performance than the Ni-W coating. The corrosion rate and surface\nroughness decreased about 50 and 5 times less than bare coating in optimum condition 8 gl-1 PTFE....
The aim of this study was to investigate the tribological behaviour of laser cladded aluminum bronze tool\nsurfaces for dry metal forming. In a first part of this work a process window for cladding aluminum bronze on steel\nsubstrate was investigated to ensure a low dilution. Therefore, the cladding speed, the powder feed rate, the laser\npower and the distance between the process head and the substrate were varied. The target of the second part was\nto investigate the influence of different process parameters on the tribological behaviour of the cladded tracks. The\nlaser claddings were carried out on both aluminum bronze and cold work tool steel as substrate materials. Two different\nparticle sizes of the cladding powder material were used. The cladding speed was varied and a post-processing\nlaser remelting treatment was applied. It is shown that the tribological behaviour of the surface in a dry oscillating\nball-on-plate test is highly dependent on the substrate material. In the third part a deep drawing tool was additively\nmanufactured by direct laser deposition. Furthermore, the tool was applied to form circular cups with and without\nlubrication....
This study reports the manufacture, microstructure, and tribological behaviour of carbon nanotube reinforced aluminium\ncomposites against pure aluminium. The specimens were fabricated using powder metallurgy method. The nanotubes in weight\npercentages of 0.5, 1.0, 1.5, and 2.0 were homogeneously dispersed and mechanically alloyed using a high energy ball milling.\nThe milled powders were cold compacted and then isothermally sintered in air. The density of all samples was measured using\nArchimedes method and all had a relative density between 92.22% and 97.74%. Vickers hardness increased with increasing CNT\nfraction up to 1.5 wt% and then reduced.The microstructures and surfaceswere investigated using high resolution scanning electron\nmicroscope (SEM). The tribological tests showed that the CNT reinforced composites displayed lower wear rate and friction\ncoefficient compared to the pure aluminium under mild wear conditions. However, for severe wear conditions, the CNT reinforced\ncomposites exhibited higher friction coefficient and wear rate compared to the pure aluminium. It was also found that the friction\nand wear behaviour of CNT reinforced composites is significantly dependent on the applied load and there is a critical load beyond\nwhich CNTs could have adverse impact on the wear resistance of aluminium....
Surface texturing has been shown to be an effective modification approach for improving\ntribological performance. This study examined the friction reduction effect generated by square\ndimples of different sizes and geometries. Dimples were fabricated on the surface of ASP2023\nsteel plates using femtosecond laser-assisted surface texturing techniques, and reciprocating sliding\nline contact tests were carried out on a Plint TE77 tribometer using a smooth 52100 bearing steel\nroller and textured ASP2023 steel plates. The tribological characterization of the friction properties\nindicated that the textured samples had significantly lowered the friction coefficient in both boundary\n(15% improvement) and mixed lubrication regimes (13% improvement). Moreover, the high data\nsampling rate results indicated that the dimples work as lubricant reservoirs in the boundary\nlubrication regime....
This study aims to use a JSEG algorithm to segment the wear particle�s image.Wear particles provide detailed information about the\nwear processes taking place between mechanical components. Autosegmentation of their images is key to intelligent classification\nsystem. This study examined whether this algorithmcan be used in particles� image segmentation. Different scales have been tested.\nCompared with traditional thresholding along with edge detector, the JSEG algorithm showed promising result. It offers a relatively\nhigher accuracy and can be used on color image instead of gray image with little computing complexity. A conclusion can be\ndrawn that the JSEG method is suited for imaged wear particle segmentation and can be put into practical use in wear particle�s\nidentification system....
Loading....