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In the present work, molecular dynamics simulations were used to investigate the impact of the tool microstructure on the wear behavior of ferrite workpiece during nanoscratching. The tool microstructure was modified by varying the carbide (cementite) contents. The simulation results show that dislocations are the primary mechanism for plastic deformation of the workpiece material. It is found that...
To enhance the efficiency of a turbo engine, one solution is reducing the clearance between the rotary parts in the secondary air system. This clearance reduction causes direct interactions in the secondary air system of a turbo engine when a rotary seal, called a labyrinth seal, rubs against the turbo engine casing as a result of successive starts and stops, thermal expansions and vibrations. To...
A large amount of research has been devoted to the effect of molybdenum dithiocarbamate (MoDTC) additives on the lubricating performances of carbon-based coatings, showing that a high wear rate is produced when the MoDTC is blended with the base oil. However, the mechanisms leading to the coating removal are not fully understood yet.In this work, the friction and wear performances of an amorphous...
Atomistic simulations were used to study the nanoscale wear of crystalline silicon with a native oxide sliding against amorphous silicon dioxide. The size, shape and crystallographic orientation of the model were defined to be comparable to those in a corresponding atomic force microscope experiment, where the tip was imaged before and after 40nm of sliding using ex situ transmission electron microscopy...
The macro- and microtribological properties of carbon nitride thin films deposited by high power impulse magnetron sputtering at different substrate bias voltages (Vb) were investigated. Vb of -100, -150, -200, and -300 V were used. A Hysitron Triboindenter TI950 and a reciprocating Tribotechnic tribometer with diamond counterparts were used in order to assess the tribological performance of the films...
In this work, we study friction and wear of laser-patterned chain links (42CrMo4 steel) using a specially modified ball-on-disk tribometer under linear reciprocating sliding (normal load of 15N and sliding velocity of 3cm/s). The results of the laser-patterned surfaces are compared to the behaviour of polished and serial chain links. Direct laser interference patterning (wavelength of 355nm and pulse...
Since experimental erosion testing is rarely feasible in the engineering practice, the estimate of erosion is often performed by numerical simulations. Computational Fluid Dynamics (CFD) codes are often equipped with utilities for wear estimation which rely on a well-established methodology. However, besides requiring stringent assumptions, this methodology involves a number of sub-models and parameterizations...
In the oil sands industry a single ultra-class shovel tip can lose more than 35kg of steel mass in one operating day. Equipment downtime is significantly increased with frequent stoppages to replace worn shovel teeth. This leads to a substantial loss in shovel availability and utilization, as well as a considerable increase in consumable cost.This paper develops a means to predict the wear performance...
A common cause for premature bearing failures in wind turbine gearboxes are the so-called White Etching Cracks (WEC). These undirected, three-dimensional cracks are bordered by regions of altered microstructure and ultimately lead to a cracking or spalling of the raceway. An accelerated WEC test was carried out on a FE8 test rig using cylindrical roller thrust bearings made of martensitic 100Cr6 steel...
This paper reviews the work done to understand cavitation damage. The paper covers the theoretical formulation of cavitation bubble collapse and the estimate of bubble collapse pressure, the techniques for measurement of cavitation damage in the laboratory and the special facilities for measurement of cavitation damage in sodium, the instrumentation for measurement of collapse pressure during cavitation...
Although diamondlike carbon coatings like WC/a-C:H have a proven history of tribological performance in many mechanical applications, studies have reported that these coatings can sometimes experience high wear rates when operating in lubricants with large concentrations of phosphorous- and sulfur-based additives. In this study, WC/a-C:H and TiC/a-C:H coatings have been tribologically tested against...
Atomic layer deposited (ALD) alumina is a promising candidate for use as a wear-resistant and protective coating in MEMS and other applications. While the tribological properties of ALD alumina may be affected by numerous factors related to processing, environment, and operating conditions, its wear behavior is neither quantified nor well understood. In this study, ALD alumina is annealed at different...
The tribology of diamond-like carbon (DLC) films has been studied for decades, but their friction and wear mechanisms at the nanoscale still remain unclear due to experimental limitations. To address this challenge, the friction and wear between DLC films and diamond tips are investigated via molecular dynamics simulations. It is found that the load can increase wear rate of the DLC film by inducing...
The object of this paper is to investigate the influence of solid solution strengthening on the spalling behavior of railway wheel steel. White etching layer (WEL) was reproduced by twin-disc test and analyzed by phase transformation kinetic. Spalling of WEL was then evaluated by rolling contact fatigue (RCF) test and finite element analysis. The results show that solid solution strengthening improves...
Contributions of exhaust and non-exhaust sources to traffic-related particulate matter (PM) pollution in the atmosphere are almost identical and the most important non-exhaust source is known to be brake wear particles. In order to understand the properties and harmful effects of wear particles on people, accurate information on size distribution of brake wear particles is needed. Our previous study...
In this study, Ti-6Al-4V dovetail joint specimens which highly simulate the attachment between the blade and disk of fan stages in a certain gas turbine engine were designed and used in fretting fatigue experiments. The fretting wear mechanism was characterized using a bench level experimental method. The effect of shot-peening on both fretting wear mechanism and fretting fatigue property was evaluated...
Over 75% of domestic electric power consumption in Colombia is supplied by hydropower. Abrasive wear is degrading turbine components such as Pelton needle valve nozzles. This problem has been studied on the components themselves (in situ). However, it was necessary reproduce the same hydro-abrasive phenomena in a controlled laboratory environment. This study describes the design and construction of...
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