Thermal Spraying Applied Onto High Energy Railway Braking: Characterization of Friction Performances

1998 ◽  
Author(s):  
H. Bartys ◽  
J.D. Guerin ◽  
J.P. Bricout ◽  
J. Oudin
Keyword(s):  
High Speed ◽  
Wear Behavior ◽  
Energy Levels ◽  
Thermal Spraying ◽  
High Energy ◽  
Coated Steel ◽  
High Speed Trains ◽  
To Come ◽  
Tribological Characterization

Abstract Optimization of constitutive friction materials of braking devices for high speed trains is endlessly on delicate increase by reason of the large energy levels to dissipate, and the lightening more and more required by generations to come. Low thermal diffusivity materials such as coated steel discs in one of the research themes in this field. Proposed study is relative to tribological characterization of the wear behavior of stellite coatings, based on cobalt or nickel alloys against aluminum titanate pad. This one has ever been tested and prooved good behavior against cermet coated steel discs. Stellite coating performances are evaluated in term of friction coefficient, contact temperature and wear in comparison with this type of disc.

Tribological Characterization of Machining at Very Small Contact Areas

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Michael R. Lovell ◽  
P. Cohen ◽  
Pradeep L. Menezes ◽  
R. Shankar
Keyword(s):  
High Speed ◽  
Friction Mechanisms ◽  
High Speed Steel ◽  
Small Scale ◽  
Machining Processes ◽  
Macroscopic Theory ◽  
Contact Areas ◽  
Tribological Characterization ◽  
Physical Phenomena

When machining miniaturized components, the contact conditions between the tool and the workpiece exhibit very small contact areas that are on the order of 10−5 mm2. Under these conditions, extremely high contact stresses are generated, and it is not clear whether macroscopic theories for the chip formation, cutting forces, and friction mechanisms are applicable. For this reason, the present investigation has focused on creating a basic understanding of the frictional behavior in very small scale machining processes so that evaluations of standard macroscale models could be performed. Specialized machining experiments were conducted on 70/30 brass materials using high-speed steel tools over a range of speeds, feeds, depths of cut, and tool rake angles. At each operating condition studied, the friction coefficient and the shear factor τk were obtained. Based on the experimental results, it was determined that the standard macroscopic theory for analyzing detailed friction mechanisms was insufficient in very small scale machining processes. An approach that utilized the shear factor, in contrast, was found to be better for decoupling the physical phenomena involved. Utilizing the shear factor as an analysis parameter, the parameters that significantly influence the friction in microscale machining processes were ascertained and discussed.

Tribological characterization of diamond-like carbon films on nonledeburitic high-speed steels

2000 ◽  
Vol 45 (3) ◽  
pp. 233-239 ◽  
Author(s):  
J Richter ◽  
I.M Hutchings ◽  
T.W Clyne ◽  
D.N Allsopp ◽  
X Peng
Keyword(s):  
High Speed ◽  
Carbon Films ◽  
Diamond Like Carbon ◽  
Tribological Characterization

scholarly journals Production and Tribological Characterization of Tailored Laser-Induced Surface 3D Microtextures

Lubricants ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 67 ◽  
Author(s):  
Joel Voyer ◽  
Johann Zehetner ◽  
Stefan Klien ◽  
Florian Ausserer ◽  
Igor Velkavrh
Keyword(s):  
Friction And Wear ◽  
Wear Behavior ◽  
Pulsed Laser ◽  
Antifriction Coating ◽  
The Coefficient Of Friction ◽  
Tribological Characterization ◽  
Steel Substrates ◽  
Different Levels ◽  
Lubrication Conditions

The aim of the present study was firstly to determine the manufacturing feasibility of a specific surface 3D-microtexturing on steel through an ultra-short pulsed laser, and secondly to investigate the tribological properties under 2 different lubrication conditions: oil-lubricated and antifriction coated. The selected 3D-microtexture consisted of 2 different levels of quadratic micropillars having side dimensions of approximately 45 µm, heights of about 35 µm and periods of 80 µm. It was shown that the production of specific 3D-microtextures on steel substrates using an ultra-short pulsed laser was feasible, and that the reproducibility of the texture dimensions over the entire textured region was extremely good. Frictional investigations have shown that, in comparison to the benchmark (untextured samples), the 3D-microtextured samples do not induce any significant improvements in the coefficient of friction (COF) under oil-lubricated conditions, but that under antifriction coated conditions, significant improvements in the friction coefficients may be achieved. Wear-based tribological tests have shown that the antifriction coating on benchmark samples was completely depleted, which greatly influenced their friction and wear behavior, since steel-steel contact occurred during testing. For the 3D-microtexture, the antifriction coating was also partially depleted; however, it accumulated itself in the microtexture which acted as a potential lubricant reservoir.

scholarly journals Harnessing Neutrino Energy for a Sustainable Future

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Priyanka Supraja Balaji ◽  
Ellen Torres Thompson ◽  
Lawrence Edmond IV ◽  
Nicole Della Santina
Keyword(s):  
Renewable Energy ◽  
Renewable Energy Sources ◽  
Energy Levels ◽  
Primary Source ◽  
High Energy ◽  
Neutrino Energy ◽  
Energy Sources ◽  
High Energy Particle ◽  
Subatomic Particles ◽  
To Come

There is a growing need for sustainable forms of renewable energy sources that are efficient, and cost-beneficial. Finding such energy sources is one of the critical challenges of the 21st century. This paper focuses on the prospects of using high energy particles abundant in the universe as a solution to the energy crisis faced around the world. The high energy particle studied in this paper is the neutrino. Neutrinos are subatomic particles that are one-millionth the size of an electron (“How much does a neutrino weigh”, n.d). They are of interest to physicists because they are present virtually everywhere, travel through regular forms of matter, and have exceptionally high energy levels (“What is a Neutrino”, 1999). Neutrinos have ten billion electron volts when traveling freely across space, which is enough energy to break up the nucleus of an atom (“Neutrino Energies”, n.d). Due to their high energy levels and eternal presence, neutrinos are a promising candidate for a renewable energy source. However, due to minimal reactions with other forms of matter, it is difficult to harness their intrinsic energies. A panel that is capable of absorbing neutrinos can potentially produce substantial amounts of heat energy, which can then be converted into electricity.  Energy from neutrinos is a great theoretical alternative and a clean source of energy for our planet and future generations to come. This paper takes another step forward in the mission to produce a primary source of energy that is green and sustainable for our planet.

Synthesis and Characterization of Nanocrystalline M50 Steel Powders by Cryomilling

1995 ◽  
Vol 400 ◽  
Author(s):  
M. L. Lau ◽  
B. Huang ◽  
R. J. Perez ◽  
S. R. Nutt ◽  
E. J. Lavernia
Keyword(s):  
High Speed ◽  
High Speed Steel ◽  
High Energy ◽  
Average Grain Size ◽  
Energy Ball ◽  
Nanocrystalline Microstructure ◽  
Al Powder ◽  
Thermal Stability Of ◽  
M50 Steel

AbstractThe present study investigated the synthesis of nanocrystalline high speed steel M50 (4.5% Mo, 4.0% Cr, 1.0% V, 0.8% C, balance Fe) by cryogenic high energy ball milling (cryomilling). Pre-alloyed M50 steel was spray atomized, and subsequently cryomilled in liquid nitrogen for 25 hours. Elemental Al powder was added prior to cryomilling in order to promote the formation of nanoscale Al2O3 and AlN particles, which improved the thermal stability of the nanocrystalline M50 steel. Following annealing at 1373 K, the M50 steel was found to retain its nanocrystalline microstructure with the average grain size of 40–80 nm.

scholarly journals Dual-energy CT characterization of winter sports injuries

2020 ◽  
Vol 93 (1106) ◽  
pp. 20190620
Author(s):  
Jonathan Hickle ◽  
Frances Walstra ◽  
Peter Duggan ◽  
Hugue Ouellette ◽  
Peter Munk ◽  
...  
Keyword(s):  
High Speed ◽  
Sports Injuries ◽  
Imaging Modality ◽  
High Energy ◽  
Dual Energy ◽  
Dual Energy Ct ◽  
Cross Sectional ◽  
Winter Sports ◽  
Conventional Ct

CT is a readily available imaging modality for cross-sectional characterization of acute musculoskeletal injuries in trauma. Dual-energy CT provides several additional benefits over conventional CT, namely assessment for bone marrow edema, metal artifact reduction, and enhanced assessment of ligamentous injuries. Winter sports such as skiing, snowboarding, and skating can result in high speed and high energy injury mechanisms; dual-energy CT is well suited for the characterization of those injuries.

Production and Characterization of Aluminium NbAl3 Composite by Mechanical Alloying and In Situ - A Process Comparison

2005 ◽  
Vol 498-499 ◽  
pp. 158-163 ◽  
Author(s):  
Severino L. Urtiga Filho ◽  
James C. Earthman ◽  
I. Nieves ◽  
Maria Helena Robert ◽  
T.P. Waked
Keyword(s):  
Mechanical Alloying ◽  
Wear Behavior ◽  
High Energy ◽  
Nitrogen Atmosphere ◽  
High Dispersion ◽  
Process Comparison ◽  
The Matrix ◽  
In Situ Formation

This work analyses the production of Al based composites with particulate reinforcement, via mechanical alloying. Composites were produced by mixing Al and NbAl3 powders by high energy mechanical alloying, under liquid nitrogen atmosphere, followed by cold pressing and hot sintering; and by controlling NbAl3 phase precipitation in liquid Al (in situ formation of the reinforcement). Results on composite produced from powders showed better distribution and incorporation, besides finer dispersion of particles in the matrix when mechanical alloying is employed. In this case, high dispersion on particulate phase was found despite predominance of small particles; there are no evidence of interface formation. When composites are produced by in situ formation of NbAl3 intermetallics, results showed that the formation of the reinforcement directly from the liquid matrix and the peritectic reaction between NbAl3 and liquid Al, provide a perfect reinforcement/matrix interface. Products showed good mechanical properties, good wear behavior and reduced thermal expansion.

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