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Atomic force microscopy (AFM) and lateral force microscopy (LFM) have been used to examine the local topography and frictional properties of anti-wear films formed during tribological testing using a reciprocating Amsler test - a laboratory mechanical test to simulate engine valve train conditions - and a real engine component. Measurements were made in ambient conditions, under a model hydrocarbon...
Several families of liquid crystals, 4,4'-dialkyl- and dialkoxyazobenzenes, 4,4'-dialkylazoxybenzenes and cyanoaryls, have been studied as commercial oils additives. Tribiological studies have been carried out on a real time pin-on-disk machine at variable temperature and concentration. Variations in viscosity and transition temperatures have no significant effect on friction values. Friction values...
A method to determine all 16 dynamic coefficients of two journal bearings from impulse responses is described. From the transfer functions of the displacements to the excitation forces, all 16 coefficients of two journal bearings can be obtained based on least-squares estimation. Computer simulation verifies that the experimentally identified coefficients approximate well the measured rotor-bearing...
Investigations into the fretting behaviour of the AlSi7Mg-T6 aluminium alloy are presented in this paper. With regard to the surface finishing conditions of the material, two types of specimen were considered: (i) machined and (ii) machined and shot peened specimens. The research was focused on investigations into the influence of the number of cycles, normal load (contact pressure) and the amplitude...
Wear of copper with different grain size (from 0.2 to 80 μm) on steel at dry friction has been studied under the following conditions: sliding velocity 0.78 m s -1 , pressure 5 MPa, and sliding distance 500 m. Results show that copper with submicrocrystalline structure has the lowest wear. The distribution of microhardness after friction on thickness of surface layer is described for...
An elastic-plastic asperity contact model for surfaces with an ion-plated soft metallic coating is presented. The model reflects the experimental observations that the wear mechanism for the coating is microcutting and that for the substrate is adhesive. The Greenwood-Williamson asperity model is used as a basis for a rough surface analysis. A modified elastic-plastic contact model is used for the...
Elastic contact between smooth, parallel, coated cylinders is considered. Results of earlier analyses are correlated using scaling factors for the contact width. This enables the contact dimension and pressure to be determined without restrictions on the elastic constants. This procedure is easily extended to the case in which both bodies are coated.
In a European research programme focused on the development and validation of test methods for thin hard coatings, friction and wear characteristics of TiN coatings were investigated. Ball-on-disc sliding tests were performed in ambient air of 50% RH at various applied loads under a fixed sliding speed. The coefficient of friction was measured on-line whereas the worn-off volume was determined by...
By considering the local pressure under a wedge indenting an elastic solid to be limited to the pressure reached when the same wedge indents a perfectly plastic solid, it is possible to calculate the pressure distribution under a wedge-shaped asperity sliding over an elasto-plastic solid. The results of this calculation agree well with finite element calculations and can be used to predict the rise...
The usefulness of WC-Co cermets as wear resistant material for coatings is determined by the cladding technique employed. This paper compares the features of an 83% WC-Co coating on an AISI 1043 steel substrate using two different application techniques: plasma spraying and laser cladding. Results show significantly less porosity, improved coating hardness and better layer-substrate adherence in laser...
The microstructural changes in worn surfaces of Mn6 and Mn13 steels before and after wear were investigated by the use of SEM, TEM and a back-scatter Mossbauer spectrometer. The results show that there exist two kinds of austenite for austenitic manganese steels before wear, one contains almost no carbon (C) and the other contains more C. The C atoms mainly exist in the octahedral interstitial sites...
In the automotive industry, the surface morphology of sheet steel is controlled to improve both paint finish and formability. Formability, in turn, is influenced by the friction between the sheet and stamping tools, which the industry commonly measures with the 'drawbead simulator' (DBS) test. This investigation evaluated the use of various surface parameters as predictors of the frictional properties...
For the ultra precision processing of higher purity aluminium disk, a high porous PVA resin bonded grinding stone including fine abrasive grains of SiC is used. Aqueous emulsion of a specific grinding fluid is very important in bringing out the best grinding ability in the grinding stone. Grinding fluids containing alkanol amine and alkyl-ether of alkylene oxide as main components were developed....
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