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On the basis of deviation theory of a random function a model has been developed for determining the parameters of acoustic emission (AE) accompanying contact friction of solids. The relationships are formulated for calculations of amplitude distribution, its parameters, and count rate of acoustic emission pulses. General characteristics of materials composing the friction pair were determined as...
X-ray absorption near edge structure (XANES) spectroscopy has been used to study the chemical nature of the antiwear films generated on steel surfaces using zinc dialkyldithiophosphates (ZDDPs). The spectra were recorded using total electron yield (TEY) and fluorescence yield (FY) to investigate the chemical nature of P, S, Ca, O and Fe on the surface and in the bulk, respectively. In the first part...
The present paper deals with the high-speed machining of Inconel 718 and Ti-6Al-6V-2Sn alloys from a thermal point of view. Temperature and wear of cutting tools are investigated by means of cutting experiments and numerical analysis up to a cutting speed of around 600 m min -1 . For Inconel 718, severe wear of ceramic tools, particularly highly developed boundary notch wear, is correlated...
By means of environmental scanning electron microscopy (ESEM), an in situ observation technique was developed to observe the agglomeration process of wear particles of silicon nitride, silicon carbide and alumina and to study the effect of water vapor on the agglomeration of wear particles. The results show that the size of the deposit of wear particles becomes smaller with increasing water vapor...
Solid particle erosion of A356 and the A356-10 vol.% SiC p composite were investigated at room temperature. The composites were fabricated by the melt stir technique and billets were hot extruded. Erosion tests were conducted on these extruded materials with and without T6 treatment. Effect of an excess addition of 0.4% magnesium to the A356 alloy and its composite were also investigated....
The antiseizure and antifriction characteristics of a number of Al-Si-Pb alloys with silicon contents in the range 2-20 wt.% and lead contents in the range 0-10 wt.% were investigated under different lubrication conditions using a bearing test machine. With continuous oil lubrication, bearings made of eutectic and hypereutectic base alloys run without seizure up to the regimes of boundary and mixed...
The microstructures of five molybdenum-boron, low carbon, bainitic steels were characterized using transmission electron microscopy and the wear behavior of the steels determined under severe rolling/sliding contact. Wear resistance was enhanced by the presence of carbide-free bainite. The degree to which the microstructure contained this form of bainite was increased by higher carbon content and...
Three kinds of Cr 3 C 2 -25%NiCr coatings prepared by APS-Ar/H 2 , APS-Ar/He and HVOF spraying, respectively, have been studied with a self-made impact wear rig. The wear resistant performances of Cr 3 C 2 -25%NiCr coatings were tested under different impact stress. The wear losses and worn surface profiles are measured, and the corresponding wear mechanisms...
X-ray absorption near edge structure (XANES) spectroscopy has been used to study the chemical nature of the antiwear films generated on steel surfaces using zinc dialkyldithiophosphates (ZDDPs), in the presence of detergents and dispersants. The spectra were recorded both in total electron yield (TEY) and fluorescence yield (FY) modes, to investigate the chemical nature of P, S, Ca and O on the surface...
The effect of double bonds in a lubricant on the friction of metal evaporated (ME) tape is presented. New carboxylic acid stearyl amine salt derivatives were used as lubricants. The double bond incorporated in the hydrophobic group of the lubricant raises the friction of the ME tape. Not only the number but the position of the double bond influences the friction. The friction coefficient of the unsaturated...
Because particulate reinforced metal matrix composites cannot be welded without unacceptable disruption of local particle distribution and matrix microstructure, they are normally joined using mechanical fasteners or adhesives, and consequently they are susceptible to fretting wear and fretting fatigue. The fretting wear behaviour of a 2124 Al-Cu-Mg alloy reinforced with a uniform distribution of...
Material transfer is a common phenomenon in dry friction, generally associated with a change in surface topography and in frictional interactions. In previous work, the actual influence of adhesion, cohesion and interfacial shear stresses on the extent of transfer (the transfer being assessed experimentally by image analysis) was established both on a theoretical and experimental basis, but at constant...
Surface engineering techniques are being considered in the hot forging industry, for improving the life of forging dies. During forging, the surfaces of the dies reach temperatures of 700-800°C. Published information on the wear performance of modified/engineered surfaces at higher temperatures is, however, scarce. To address this situation, a high-temperature pin-on-disc machine was modified into...
Engineered injection molded plastics are now common substrates of choice for painted bumper fascias in the automotive industry. A major challenge for painted fascias involves potential warranty costs associated with various tribological scenarios that can result in moderate to severe paint delamination. Preliminary failure analysis performed on field specimens indicate surface damage in majority of...
A unidirectional silicon carbide continuous fibre reinforced calcium aluminosilicate (CAS/SiC) glass-ceramic matrix composite has been subjected to silica sand solid particle erosion over the temperature range 20 to 726°C. At room temperature, tests were conducted at two velocities. The lower (7 m s -1 ) did not generate lateral cracks and a wear rate of 0.004 mg g -1 was...
Dry sliding tests were carried out under different load and sliding speed conditions on Ti-6Al-4V alloy plasma nitrided at three temperatures: 973, 1073 and 1173 K. The results were interpreted on the basis of the evolution of the friction coefficient and by characterizing the wear debris and worn surfaces in order to understand the acting wear mechanisms. A comparison was also made with the results...
When a hard rough surface slides repeatedly on a softer component a system of protective residual stresses may be developed in the near-surface layers of the weaker material which enable loads sufficiently large to cause plastic deformation in the early cycles of loading to be accommodated purely elastically in the later stages of the loading history. This is the process known as shakedown and limits...
The friction and wear characteristics of zinc-based alloys in warm, oil-lubricated, sliding contact against mild steel were investigated. The alloys, their compositions, and their microstructures included: pure Zn (100% Zn, η zinc), Zamak 3 (Zn-4Al-O.1Cu, η zinc plus η/α eutectic), ZA 27 (Zn-31Al-2.3Cu, α aluminum plus η/α eutectic), ACuZinc 5 (Zn-3.0Al-5Cu) in die cast form, and ACuZinc 10 (Zn-3...
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