The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Anne Neville - One of the best experts on this subject based on the ideXlab platform.
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Surface Fatigue Behavior of a WC/aC:H Thin-Film and the Tribochemical Impact of Zinc Dialkyldithiophosphate.
ACS applied materials & interfaces, 2019Co-Authors: Siavash Soltanahmadi, Ileana Nedelcu, Ardian Morina, Thibaut V.j. Charpentier, Vishal Khetan, Helen M. Freeman, Andrew P. Brown, Rik Brydson, Marcel C. P. Van Eijk, Anne NevilleAbstract:In wind turbine gearboxes, (near-)Surface initiated Fatigue is attributed to be the primary failure mechanism. In this work, the Surface Fatigue of a hydrogenated tungsten carbide/amorphous carbon ...
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Surface reaction films from amine based organic friction modifiers and their influence on Surface Fatigue and friction
Tribology Letters, 2019Co-Authors: Siavash Soltanahmadi, Erfan Abedi Esfahani, Marcel C P Van Eijk, Ileana Nedelcu, Ardian Morina, Anne NevilleAbstract:Surface reactive additives are crucial in the lubrication of Surfaces experiencing cyclic contact. The combination of additives in the lubricant, on the material Surface and the complex tribo-contact conditions hinders the design of additive packages which can simultaneously protect steel Surfaces from wear and Fatigue. Amine-based Organic Friction Modifiers (OFMs) influence the tribological performance of steel Surfaces. This study investigates the tribochemical impact of three amine-based OFMs in combination with Zinc DialkylDithioPhosphate (ZDDP) on tribological performance, particularly Surface Fatigue, for steel Surfaces in severe rolling–sliding contacts. The thickness of reaction films was tracked throughout experiments and the chemistry of reaction films was examined using X-ray Photoelectron Spectroscopy (XPS). Results highlight the impact of the OFM polar moiety on tribological performance and its influence on chemical composition of tribo-reaction films and their formation kinetics. The combination of selected OFMs with ZDDP reduces frictional forces and can mitigate Surface Fatigue under certain conditions.
Siavash Soltanahmadi - One of the best experts on this subject based on the ideXlab platform.
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Surface Fatigue Behavior of a WC/aC:H Thin-Film and the Tribochemical Impact of Zinc Dialkyldithiophosphate.
ACS applied materials & interfaces, 2019Co-Authors: Siavash Soltanahmadi, Ileana Nedelcu, Ardian Morina, Thibaut V.j. Charpentier, Vishal Khetan, Helen M. Freeman, Andrew P. Brown, Rik Brydson, Marcel C. P. Van Eijk, Anne NevilleAbstract:In wind turbine gearboxes, (near-)Surface initiated Fatigue is attributed to be the primary failure mechanism. In this work, the Surface Fatigue of a hydrogenated tungsten carbide/amorphous carbon ...
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Surface reaction films from amine based organic friction modifiers and their influence on Surface Fatigue and friction
Tribology Letters, 2019Co-Authors: Siavash Soltanahmadi, Erfan Abedi Esfahani, Marcel C P Van Eijk, Ileana Nedelcu, Ardian Morina, Anne NevilleAbstract:Surface reactive additives are crucial in the lubrication of Surfaces experiencing cyclic contact. The combination of additives in the lubricant, on the material Surface and the complex tribo-contact conditions hinders the design of additive packages which can simultaneously protect steel Surfaces from wear and Fatigue. Amine-based Organic Friction Modifiers (OFMs) influence the tribological performance of steel Surfaces. This study investigates the tribochemical impact of three amine-based OFMs in combination with Zinc DialkylDithioPhosphate (ZDDP) on tribological performance, particularly Surface Fatigue, for steel Surfaces in severe rolling–sliding contacts. The thickness of reaction films was tracked throughout experiments and the chemistry of reaction films was examined using X-ray Photoelectron Spectroscopy (XPS). Results highlight the impact of the OFM polar moiety on tribological performance and its influence on chemical composition of tribo-reaction films and their formation kinetics. The combination of selected OFMs with ZDDP reduces frictional forces and can mitigate Surface Fatigue under certain conditions.
Dennis P. Townsend - One of the best experts on this subject based on the ideXlab platform.
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Increased Surface Fatigue Lives of Spur Gears by Application of a Coating
Journal of Mechanical Design, 2004Co-Authors: Timothy L. Krantz, Dennis P. Townsend, Clark V. Cooper, Bruce D. HansenAbstract:ABSTRACT Hard coatings have potential for increasing gear Surface Fatigue lives. Experiments were conducted using gears both with and without a metal-containing, carbon-based coating. The gears were case-carburized AISI 9310 steel spur gears. Some gears were provided with the coating by magnetron sputtering. Lives were evaluated by accelerated life tests. For uncoated gears, all of fifteen tests resulted in Fatigue failure before completing 275 million revolutions. For coated gears, eleven of the fourteen tests were suspended with no Fatigue failure after 275 million revolutions. The improved life owing to the coating, approximately a six-fold increase, was a statistically significant result. Keywords: Gear, life, Fatigue, pitting, coatings. INTRODUCTION The power density of a gearbox is an important consideration for many applications and is especially important for gearboxes used on aircraft. One factor that limits gearbox power density is the need to transmit power for the required number of cycles while avoiding gear Surface Fatigue failure (micropitting, pitting or spalling). Effective and economical methods for improving Surface Fatigue lives of gears are therefore highly desirable. Thin hard coatings have potential for improving gear performance. In fact, coatings are reported to have some successful applications [1-3] where product durability improvements have been achieved by the application of thin hard coatings to gears. Diamond-like carbon and related materials have the potential for a wide variety of applications that require wear protection and/or low-friction properties. Because of the widely recognized potential, the deposition methods and resulting properties of the films have been studied extensively [4-6]. Today’s deposition technology allows for the production of a great diversity of coatings, but the ability to tailor the tribological behavior of a coating for a particular application has been elusive. Aerospace gearing requirements are demanding, calling for high power density, long life, and excellent reliability. The low friction properties and high hardness of diamond-like and related coatings offer the possibility to improve the performance of aerospace gearing. Naik, et al [7] tested the adherence and toughness of two coatings using both disk-on-rod rolling-contact and gear tests, and they reported promising results. Alanou, et al [8] found that coatings could increase the scuffing load capacity of rolling and sliding disks used to simulate aerospace gearing contacts, but they also reported poor adherence for one particular substrate and coating combination. Joachim, Kurz and Glatthaar [3] reported promising results of evaluations of tungsten carbon carbide and amorphous boron carbide coatings using laboratory tests, but they also report mixed results when applying such coatings to commercial applications. The purpose of the present investigation was to compare the Surface Fatigue lives of coated and uncoated gears using accelerated life tests. The testing is considered as accelerated in that the contact stresses used for testing exceeds the stresses used for design of the target application (helicopter gearing). The metal-containing, carbon-based diamond-like (Me-DLC) coating selected for this study was designed specifically for the aerospace gearing applications. NASA/TM—2003-2124631
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Increased Surface Fatigue Lives of Spur Gears by Application of a Coating
Volume 4: 9th International Power Transmission and Gearing Conference Parts A and B, 2003Co-Authors: Timothy L. Krantz, Dennis P. Townsend, Clark V. Cooper, Bruce D. HansenAbstract:Hard coatings have potential for increasing gear Surface Fatigue lives. Experiments were conducted using gears both with and without a metal-containing, carbon-based coating. The gears were case-carburized AISI 9310 steel spur gears. Some gears were provided with the coating by magnetron sputtering. Lives were evaluated by accelerated life tests. For uncoated gears, all of fifteen tests resulted in Fatigue failure before completing 275 million revolutions. For coated gears, eleven of the fourteen tests were suspended with no Fatigue failure after 275 million revolutions. The improved life owing to the coating, approximately a six-fold increase, was a statistically significant result.Copyright © 2003 by ASME
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New Lubricants Increase Surface-Fatigue Lives Of Gears
1995Co-Authors: Dennis P. Townsend, John ShimskiAbstract:Report describes experimental study of effectiveness of seven oils with various additives and viscosities in prolonging Surface-Fatigue lives of spur gears. Experiments conducted on pairs of meshing spur gears of 3.5-in. (8.89-cm) pitch diameter, all fabricated to same specifications from same lot of steel.
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New Lubricants Increase Surface-Fatigue Lives Of Gears
1995Co-Authors: Dennis P. Townsend, John ShimskiAbstract:Report describes experimental study of effectiveness of seven oils with various additives and viscosities in prolonging Surface-Fatigue lives of spur gears. Experiments conducted on pairs of meshing spur gears of 3.5-in. (8.89-cm) pitch diameter, all fabricated to same specifications from same lot of steel.
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The Surface Fatigue Life of Contour Induction Hardened AISI 1552 Gears.
1995Co-Authors: Dennis P. Townsend, Alan Turza, Mike ChaplinAbstract:Abstract : Two groups of spur gears manufactured from two different materials and heat treatments were endurance tested for Surface Fatigue life. One group was manufactured from MSI 1552 and was finished ground to a 0.4 um (16 um.) rms. Surface finish and then dual frequency contour induction hardened. The second group was manufactured from CEVM AISI 9310 and was carburized, hardened, and ground to a 0.4 um (16 uin.) rms. Surface finish. The gear pitch diameter was 8.89 cm (3.5 in.). Test conditions were a maximum Hertz stress of 1.71 OPa (248 ksi), a bulk gear temperature of approximately 350 K (170F) and a speed of 10000 rpm. The lubricant used for the tests was a synthetic paraffinic oil with an additive package. The test results showed that the 10 percent Surface Fatigue (pitting) life of the contour hardened AISI 1552 test gears was 1.7 times that of the carburized and hardened AISI 9310 test gears. Also there were two early failures of the AlSI 1552 gears by bending Fatigue. (MM)
André Bernard Vannes - One of the best experts on this subject based on the ideXlab platform.
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Surface Fatigue behaviour mapping of PVD coatings for mechanical purposes
Tribotest, 2005Co-Authors: François Ledrappier, Yves Gachon, Cécile Langlade, André Bernard VannesAbstract:Most mechanical components used for transmission of movement are subjected to repeated impacts or cyclic stress. If these elements are well designed and the materials well chosen, their durability is linked to Surface Fatigue mechanisms. In order to improve the Fatigue behaviour of these parts, hard coatings, such as physical vapour deposition (PVD) or plasma-assisted chemical vapour deposition (PACVD) coatings, can be appropriate. Unfortunately, such hard coatings cannot be used for elements whose replacement is more difficult than, say, cutting tools. An understanding of failure mechanisms should make it possible to optimise the Fatigue behaviour of hard coatings. In order to study the Surface Fatigue behaviour of thin, hard PVD coatings, a special apparatus has been developed to carry out repeated impacts over a broad range of speeds. The possibility of mapping the Fatigue behaviour of different coatings is illustrated through the examples of TiN and TiN/CrN multilayer coatings of different thicknesses deposited on several substrates.
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Tribologically transformed structure of titanium alloy (TiAl6V4) in Surface Fatigue induced by repeated impacts
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: A.c. Sekkal, Cécile Langlade, André Bernard VannesAbstract:Abstract Under repeated impact solicitation in the elasto-plastic regime, Ti–6 wt.% Al–4 wt.% V (TiAl6V4) titanium alloy undergoes Surface Fatigue that leads to microstructural transformation and to wear. This tribologically transformed structure (TTS) appears after a given number of cycles, which depends on the impact parameters (kinetic energy, speed impact, indenter radius) and on the materials properties of the sample. Microstructural characterizations have been performed using different techniques i.e. optical microscopy, scanning electron microscopy, energy-dispersive X-ray fluorescence analyses. Transmission electron microscopy as well as nano-indentation tests reveal that the TTS structure has a typical grain size of less than 100 μm without preferential orientation and consists of α(hcp) phase with a very high (nano) hardness of 7.5 GPa.
Ardian Morina - One of the best experts on this subject based on the ideXlab platform.
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Surface Fatigue Behavior of a WC/aC:H Thin-Film and the Tribochemical Impact of Zinc Dialkyldithiophosphate.
ACS applied materials & interfaces, 2019Co-Authors: Siavash Soltanahmadi, Ileana Nedelcu, Ardian Morina, Thibaut V.j. Charpentier, Vishal Khetan, Helen M. Freeman, Andrew P. Brown, Rik Brydson, Marcel C. P. Van Eijk, Anne NevilleAbstract:In wind turbine gearboxes, (near-)Surface initiated Fatigue is attributed to be the primary failure mechanism. In this work, the Surface Fatigue of a hydrogenated tungsten carbide/amorphous carbon ...
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Surface reaction films from amine based organic friction modifiers and their influence on Surface Fatigue and friction
Tribology Letters, 2019Co-Authors: Siavash Soltanahmadi, Erfan Abedi Esfahani, Marcel C P Van Eijk, Ileana Nedelcu, Ardian Morina, Anne NevilleAbstract:Surface reactive additives are crucial in the lubrication of Surfaces experiencing cyclic contact. The combination of additives in the lubricant, on the material Surface and the complex tribo-contact conditions hinders the design of additive packages which can simultaneously protect steel Surfaces from wear and Fatigue. Amine-based Organic Friction Modifiers (OFMs) influence the tribological performance of steel Surfaces. This study investigates the tribochemical impact of three amine-based OFMs in combination with Zinc DialkylDithioPhosphate (ZDDP) on tribological performance, particularly Surface Fatigue, for steel Surfaces in severe rolling–sliding contacts. The thickness of reaction films was tracked throughout experiments and the chemistry of reaction films was examined using X-ray Photoelectron Spectroscopy (XPS). Results highlight the impact of the OFM polar moiety on tribological performance and its influence on chemical composition of tribo-reaction films and their formation kinetics. The combination of selected OFMs with ZDDP reduces frictional forces and can mitigate Surface Fatigue under certain conditions.
