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Wear Tests (wear + test)
Selected AbstractsProcessing and Tribological Properties of Si3N4/Carbon Short Fiber CompositesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2003Hideki Hyuga Si3N4/carbon fiber composites were fabricated using several types of fiber. All the composites had higher fracture toughness compared with monolithic Si3N4 ceramics. Tribological properties were investigated by a ball-on-disk method under unlubricated conditions. The composite containing fibers with a high orientation of graphite layers and high graphite content indicated a low friction coefficient. It was identified, by Raman spectroscopy, that graphite was transferred from the composite to the Si3N4 ball of the counterbody during the wear test. This transferred layer was effective for producing the low friction behavior of the composite. [source] Development and high stress abrasive wear behavior of milled carbon fiber-reinforced epoxy gradient compositesPOLYMER COMPOSITES, Issue 7 2008Navin Chand Milled carbon fiber-reinforced polysulfide-modified epoxy gradient composites have been developed. Density and hardness increases with the increase of carbon fiber content in the direction of centrifugal force, which shows the formation of gradient structure in the composite. High stress abrasive wear test was conducted on the gradient composites by using a Suga Abrasion Wear Tester. Abrasive wear rate reduced on increase of milled carbon fiber content from 0.15 to 1.66 vol%. Reduction in abrasive wear rate in milled carbon fiber-reinforced epoxy gradient composites has been attributed to the increase of hardness, presence of random milled fibers, and debris of composite materials, which gave resistance and reduced wear rate. There is a small decrease in specific wear rate on adding 0.15 vol% milled carbon fibers. Further decrease of specific wear rate is observed on adding 0.45 vol% milled carbon fibers. After 3 N load, there is a decrease in specific wear rate behavior on adding 0.45 vol% carbon fibers, which further decreases on adding 0.60 vol% of carbon fibers. There is a remarkable decrease in specific wear rate up to 5 N load for 1.66 vol% milled carbon fiber-reinforced composite. Reduction in specific wear rate on adding milled carbon fibers is based on the formation of debris, which remained intact in their respective positions due to the interfacial adhesion between milled carbon fibers and epoxy resin. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] Unlubricated Wear Behavior of Ce-TZP/ Al2O3 Nanocomposites Against Bearing Steel,ADVANCED ENGINEERING MATERIALS, Issue 3 2005G. Yang Unlubricated friction and wear tests of Ce-TZP/Al2O3 nanocomposites against bearing steel were performed. In order to elucidate the wear mecahnism, the morphological investigation and phase structural analysis of worn surfaces were carried out by X-ray diffractometer and scanning electron microscope. Additionally, three kinds of wear mechanisms such as plastic deformation, adhesive wear and brittle fracture have been revealed. [source] Wear Mechanisms of TiB2 and TiB2,TiSi2 at Fretting Contacts with Steel and WC,6 wt% CoINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 1 2010Golla Brahma Raju Unlubricated fretting wear tests on TiB2 and TiB2,5 wt% TiSi2 ceramics against two different mating materials (bearing grade steel and WC,6 wt% Co balls) were performed with a view to understand the counterbody-dependent difference in friction and wear properties. The fretting experiments were conducted systematically by varying load (2,10 N) at an oscillating frequency of 4 Hz and 100 ,m linear stroke, for a duration of 100,000 cycles. Adhesion, abrasion, and three-body wear have been observed as mechanisms of material damage for both the TiB2/steel and TiB2/WC,Co tribosystems. The third body is predominantly characterized as tribochemical layer for TiB2/steel and loose wear debris particles for TiB2/WC,Co tribocouple. An explanation on differences in tribological properties has been provided in reference to the counterbody material as well as microstructure and mechanical properties of flat materials. [source] Application of an Artificial Neural Network for Simulating Robust Plasma-Sprayed Zirconia CoatingsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2008Ming-Der Jean This article presents the application of the artificial neural network (ANN) of a statistically designed experiment for developing a robust wear-resistant zirconia coating. In this research, experimental design with orthogonal arrays efficiently provides enough information with the least number of experiments, reducing the cost and time. A radial basis function (RBF) network for the wear behavior is adopted. The friction and tribological properties of zirconia coatings were investigated. The microstructural feature of the coatings is also addressed in this study. It is found that the worn volumes of plasma-sprayed zirconia coatings after wear tests are greatly improved by the optimal parameters. The relationships between the microstructure of the worn surface and their properties are examined, and the results reveal a higher wear resistance and a lower worn surface roughness with a large amount of plastic deformations. These wear resistant structures formed as a result of a dense lamellar formation during sprayed zirconia coatings. The RBF network can be established efficiently. A comparison of the predicted results with that of the RBF network and the Taguchi method predictor shows average errors of 2.735% and 9.191% for the RBF network and the Taguchi method, respectively. It is experimentally confirmed that the RBF network predictions are in agreement with the experiments, and it can be reliably used for the prediction of wear for plasma sprayings. The experimental results demonstrate that the RBF network used for a statistically designed experiment is an effective, efficient, and intelligent approach for developing a robust, high efficiency, and high-quality zirconia coating process. [source] The comparison of wear properties of different Fe-based hardfacing alloys in four kinds of testing methodsLUBRICATION SCIENCE, Issue 4 2008E. Badisch Abstract Iron-based hardfacing alloys are widely used to protect machinery equipment. A strong correlation is given between microstructure and chemical composition of welding deposit with the resulting wear behaviour. Concerning precipitation of metallurgical hard phases and synthetic added hard particles, the bonding strength of the hard phases in the metallic matrix seems to play a dominating role to obtain high wear resistance. The main objective of this study was to evaluate the wear behaviour for pure abrasion, combined impact/abrasion and high impact wear, respectively, for four different Fe-based hardfacing alloys. Tests were performed with a standard ASTM G65 dry-sand/rubber-wheel tester. An impeller,tumbler apparatus enabled investigation of impact abrasion wear tests. Additional wear tests with high impact loading were performed on a drop hammer apparatus. Fracture surface analysis was carried out after drop hammer testing and results were correlated with microstructure and interfacial bonding behaviour of precipitations in metallic matrix. Copyright © 2008 John Wiley & Sons, Ltd. [source] Geometric effects in high-temperature vapour-phase lubrication using hydrocarbon feed gasesLUBRICATION SCIENCE, Issue 2 2002J. E. Gardner Abstract The effectiveness of ,far-field' vapour-phase lubrication, in which areas of a bearing surface that are cycled through the contact are exposed to vapour while outside the contact, has been demonstrated in both sliding and combined roll slide tests using acetylene vapours to deposit pyrolytic graphite. Friction coefficients as low as , = 0.008 have been measured for steel at 540°C with far-field acetylene concentrations as low as 5%. Effective vapour-phase lubrication depends on solid lubricant deposition that exceeds the contact's capacity to remove solid lubricant through wear. While the rate of removal is increased by increasing the sliding velocity, in far-field vapour-phase lubrication the rate of lubricant deposition, and therefore the lubrication effectiveness, is augmented by increased areas available for far-field deposition, such as those provided by performing wear tests with increased wear-track diameters. These geometric concepts may be considered in rolling-element bearing and gear set applications where vapour-phase lubrication is to be employed. [source] An ESCA study of the effectiveness of antiwear and extreme-pressure additives based on substituted phosphorodithioate derivatives, and a comparison with ZDDPLUBRICATION SCIENCE, Issue 2 2001M. C. Jain Ashless substituted dithiophosphoric acid derivatives (ADPs) are a new generation of multifunctional additives with promising antiwear (AW) and extreme-pressure (EP) characteristics. Three such additives synthesised in the authors' laboratory have been evaluated for their AW and EP properties by standard four-ball friction and wear tests. The friction-reducing properties of these additives were compared with those of a commercial zinc dialkyldithiophosphate (ZDDP). It was found that the phosphorodithioate compounds studied here possessed excellent AW/EP properties. Their AW characteristics were found to be comparable to those of ZDDP at low loads. However, at higher loads they show inferior AW characteristics in comparison to ZDDP. Nevertheless, ADP derived from cashew nut shell oil had a higher load-carrying capacity than ZDDP. The mechanism of the AW and EP behaviour exhibited by the different additives was investigated using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and scanning electron microscopy (SEM) of the worn surfaces formed during friction. XPS and AES analyses of the worn surfaces reveal that the tribochemical film formed on the ADP-tested surfaces consisted mainly of metal phosphates and only a small amount of metal sulphides, even though the ADPs contained twice the number of sulphur atoms than phosphorus atoms. The ZDDP-tested surface showed a mixture of metal sulphides and metal phosphates. Alkylamino substitution appeared to have no significant effect on the AW/EP properties of the additive. XPS and AES analyses also revealed that the tribochemical film formed on an ADP-tested surface was thicker than that present on the ZDDP-tested surface at low loads, whereas at higher loads the reverse was true. The higher weld load obtained for the blend containing cashew nut shell oil-derived ADP is attributed to the thicker adsorbed reaction film formed on the surface due to the long alkyl groups present in the original additive structure. Short-chain alkyl groups, however, form only a thin adsorbed layer, which may get rubbed off during the friction at high load. The low sulphide formation on ADP-tested surfaces was attributed to the absence of any metal atom in the additive, which would help in the formation of metal sulphides during tribofragmentation and further tribochemical reactions. [source] Mechanical and tribological characterization of CNx films deposited by d.c. magnetron sputteringPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2007L. Ipaz Abstract Carbon nitride (CNx) thin films were deposited onto silicon and steel substrates at 400 °C from a carbon target by d.c. magnetron sputtering system. The composition, structural, and mechanical properties of deposited films were investigated as a function of argon/nitrogen concentration and sputtering power, by means of Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy (RS), and nanoindentation. The EDS and Elastic Forward Analisys Analysis (EFA) showed that the nitrogen concentration in the CNx deposited films varied between 16% and 28% at depending on nitrogen concentrations in argon/nitrogen gas mixture, and deposition power. FTIR analysis indicated the presence of 2266 and 2278 cm,1 stretching peaks associated with CN triple bonds of nitriles and isocyanides, 1640 cm,1 and 1545 cm,1 associated with the C=C and C=N bonds. The thickness of the CNx deposited films varied between 0.4 and 0.8 µm at different sputtering powers. The hardness and Young's modulus were investigated by depth sensing nanoindentation method. The obtained hardness and Young's modulus increased from 4 to 17 GPa, and from 50 to 170 GPa, respectively; when the nitrogen content in the deposited films diminished between 28 and 12%. On the other hand, the friction and wear tests were done using a pin-on-disc tribometer. The friction tests showed values of 0.05 and 0.4 in dry air and humid atmosphere; respectively. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||