scholarly journals Effect of Nitrogen Implantation on Metal Transfer during Sliding Wear under Ambient Conditions

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Luke Autry ◽  
Harris Marcus
Keyword(s):  
Wear Mechanism ◽  
Heat Treating ◽  
Metal Transfer ◽  
Interstitial Free ◽  
Volumetric Wear ◽  
Ambient Conditions ◽  
Nitrogen Implantation ◽  
Stick Slip ◽  
Near Surface ◽  
Slip Mechanism

Nitrogen implantation in Interstitial-Free steel was evaluated for its impact on metal transfer and 1100 Al rider wear. It was determined that nitrogen implantation reduced metal transfer in a trend that increased with dose; the Archard wear coefficient reductions of two orders of magnitude were achieved using a dose of 2e17 ions/cm2, 100 kV. Cold-rolling the steel and making volumetric wear measurements of the Al-rider determined that the hardness of the harder material had little impact on volumetric wear or friction. Nitrogen implantation had chemically affected the tribological process studied in two ways: directly reducing the rider wear and reducing the fraction of rider wear that ended up sticking to the ISF steel surface. The structure of the nitrogen in the ISF steel did not affect the tribological behavior because no differences in friction/wear measurements were detected after postimplantation heat treating to decompose the as-implantedε-Fe3N toγ-Fe4N. The fraction of rider-wear sticking to the steel depended primarily on the near-surface nitrogen content. Covariance analysis of the debris oxygen and nitrogen contents indicated that nitrogen implantation enhanced the tribo-oxidation process with reference to the unimplanted material. As a result, the reduction in metal transfer was likely related to the observed tribo-oxidation in addition to the introduction of nitride wear elements into the debris. The primary Al rider wear mechanism was stick-slip, and implantation reduced the friction and friction noise associated with that wear mechanism. Calculations based on the Tabor junction growth formula indicate that the mitigation of the stick-slip mechanism resulted from a reduced adhesive strength at the interface during the sticking phase.

Hysteresis Identification of Carbon Nanotube Composite Beams

2018 ◽  
Author(s):  
Michela Taló ◽  
Walter Lacarbonara ◽  
Giovanni Formica ◽  
Giulia Lanzara
Keyword(s):  
Phenomenological Model ◽  
Differential Evolution Algorithm ◽  
Hysteresis Loops ◽  
Hysteretic Behavior ◽  
Damping Capacity ◽  
Stick Slip ◽  
Slip Mechanism ◽  
Material Optimization ◽  
Constitutive Parameters ◽  
Mean Square Errors

Nanocomposites made of a hosting polymer matrix integrated with carbon nanotubes as nanofillers exhibit an inherent hysteretic behavior arising from the CNT/matrix frictional sliding. Such stick-slip mechanism is responsible for the high damping capacity of CNT nanocomposites. A full 3D nonlinear constitutive model, framed in the context of the Eshelby-Mori-Tanaka theory, reduced to a 1D phenomenological model is shown to describe accurately the CNT/polymer stick-slip hysteresis. The nonlinear hysteretic response of CNT nanocomposite beams is experimentally characterized via displacement-driven tests in bending mode. The force-displacement cycles are identified via the phenomenological model featuring five independent constitutive parameters. A preliminary parametric study highlights the importance of some key parameters in determining the shape of the hysteresis loops. The parameter identification is performed via one of the variants of a genetic-type differential evolution algorithm. The nanocomposites hysteresis loops are identified with reasonably low mean square errors. Such outcome confirms that the 1D phenomenological model may serve as an effective tool to describe and predict the nanocomposite nonlinear hysteretic behavior towards unprecedented material optimization and design.

Stick-slip mechanism in a granular medium

2010 ◽  
Vol 46 (6) ◽  
pp. 600-605 ◽  
Author(s):  
A. P. Bobryakov
Keyword(s):  
Granular Medium ◽  
Stick Slip ◽  
Slip Mechanism

Studies on Friction and Formation of Transfer Layer in HCP Metals

2008 ◽  
Author(s):  
Pradeep L. Menezes ◽  
Kishore ◽  
Satish V. Kailas
Keyword(s):  
Coefficient Of Friction ◽  
Surface Texture ◽  
Soft Materials ◽  
Hard Material ◽  
Layer Formation ◽  
Ambient Conditions ◽  
Transfer Layer ◽  
Stick Slip ◽  
Stick Slip Motion ◽  
Slip Motion

Surface texture plays an important role as it predominantly controls the frictional behavior and transfer layer formation at the contacting surfaces. In the present investigation, basic studies were conducted using inclined pin-on-plate sliding tester to understand the role of surface texture of hard material on coefficient of friction and transfer layer formation when sliding against soft materials. HCP materials such as pure Mg and pure Zn were used as pins while 080 M40 steel was used as plate in the tests. Two surface parameters of steel plates — roughness and texture — were varied in the tests. Tests were conducted in ambient conditions under both dry and lubricated conditions. The morphologies of the worn surfaces of the pins and the formation of transfer layer on the counter surfaces were observed using a scanning electron microscope. It was observed for both the pin materials that the occurrence of stick-slip motion, the transfer layer formation and the value of coefficient of friction as well as its two components, namely, adhesion and plowing, depend primarily on surface texture. The effect of surface texture on coefficient of friction was attributed to the variation of plowing component of friction for different surfaces. Both the plowing component of friction and amplitude of stick-slip motion were highest for the surface texture that promotes plane strain conditions while these were lowest for the texture that favors plane stress conditions at the interface.

Cyclic extrusion of a lava dome based on a stick-slip mechanism

2012 ◽  
Vol 337-338 ◽  
pp. 39-46 ◽  
Author(s):  
A. Costa ◽  
G. Wadge ◽  
O. Melnik
Keyword(s):  
Lava Dome ◽  
Stick Slip ◽  
Slip Mechanism

Application Research of Stick-Slip Mechanism on MW Wind Turbine Yaw System

2012 ◽  
Vol 220-223 ◽  
pp. 463-468
Author(s):  
Xiao Guang Li ◽  
Ping Zhao ◽  
Jie Zhong
Keyword(s):  
Wind Turbine ◽  
Damping Ratio ◽  
Kinematic Model ◽  
Torsional Stiffness ◽  
Application Research ◽  
Stick Slip ◽  
Rotating Speed ◽  
Slip Mechanism ◽  
Simulation Calculation ◽  
Stick Slip Motion

The “stick-slip” motion or creep phenomenon is often observed in MW wind turbine yaw system. Yam system stick-slip coupling phenomenon was analyzed, and stick-slip coupling kinematic model was established and simulated by Simulink. The influence of torsional stiffness, friction coefficient difference, rotating speed, damping ratio and tightening torque on system was researched. Main measures for elimination of stick-slip coupling phenomenon were given through theoretical analysis and simulation calculation.

Long-term recordings at the FSU Jena Geodynamic Observatory Moxa (Thuringia, central Germany)

2021 ◽  
Author(s):  
Nina Kukowski ◽  
Ronny Stolz ◽  
Theo Scholtes ◽  
Cornelius Schwarze ◽  
Andreas Goepel
Keyword(s):  
Fluid Flow ◽  
Superconducting Gravimeter ◽  
Global Network ◽  
Beyond The Standard Model ◽  
Ambient Conditions ◽  
Near Surface ◽  
Exotic Physics ◽  
Climate Station ◽  
Downhole Temperature

<p>The remote location of the Geodynamic Observatory Moxa of Friedrich-Schiller University Jena, about 30 km south of Jena in the Thuringian slate mountains, results in very low ambient noise and thus very good conditions for long-term geophysical observations, which are further improved, as many sensors are installed in the subsurface in galleries or in boreholes.</p><p>So far, the focus of Moxa observatory has been on observing transients signals of deformation and fluid movements in the subsurface. This is accomplished by sensors like a superconducting gravimeter CD-034, three laser strain meters measuring nano-strain along three galleries in north-south, east-west and NW-SE directions, or borehole tiltmeters. Further, information on fluid flow is gained from downhole temperature measurements employing an optical fiber. These sensors are complemented by a climate station and two shallow drill-holes, one of which has been fully cored, which in addition to the temperature times series provide information on water level and rock physical properties. Near surface geophysical profiling using e.g. electrical resistivity tomography has led to a good knowledge of the structurally complex subsurface of the observatory.</p><p>Recently, a node for the Global Network of Optical Magnetometers for Exotic physics (GNOME) has been installed in the temperature-stabilized room at Moxa observatory close to the superconducting gravimeter. The GNOME is a world-spanning collaboration employing optically pumped magneto­meters (OPM) to search for space-time correlated transient signatures heralding exotic physics beyond the Standard Model. GNOME is sensitive to prominent classes of dark-matter scenarios, e.g., axion or axion-like particles forming macroscopic structures in the Universe. The installation in close vicinity to the superconducting gravimeter ensures well-controlled and -monitored ambient conditions such as temperature, air pressure and especially vibrations, allowing improved vetoing of false-positive detection events in the Moxa GNOME node.</p><p>Here, we focus on introducing Moxa Observatory’s sensor systems with an emphasis of actual sensor configurations and further on highlighting how various information on fluid flow coming from the specific sensors lead to an improved understanding of the direction and magnitude of subsurface fluid flow.</p>

Studies on Friction and Formation of Transfer Layer in HCP Metals

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Pradeep L. Menezes ◽  
Kishore ◽  
Satish V. Kailas ◽  
Michael R. Lovell
Keyword(s):  
Surface Texture ◽  
Steel Plates ◽  
Ambient Conditions ◽  
Transfer Layer ◽  
Stick Slip ◽  
The Coefficient Of Friction ◽  
Hcp Materials ◽  
Stick Slip Motion ◽  
Slip Motion

Surface texture plays an important role in the frictional behavior and transfer layer formation of contacting surfaces. In the present investigation, basic experiments were conducted using an inclined pin-on-plate sliding apparatus to better understand the role of surface texture on the coefficient of friction and the formation of a transfer layer. In the experiments, soft HCP materials such as pure Mg and pure Zn were used for the pins and a hardened 080 M40 steel was used for the plate. Two surface parameters of the steel plates—roughness and texture—were varied in tests that were conducted at a sliding speed of 2 mm/s in ambient conditions under both dry and lubricated conditions. The morphologies of the worn surfaces of the pins and the formation of the transfer layer on the counter surfaces were observed using a scanning electron microscope. In the experiments, the occurrence of stick-slip motion, the formation of a transfer layer, and the value of friction were recorded. With respect to the friction, both adhesion and plowing components were analyzed. Based on the experimental results, the effect of surface texture on the friction was attributed to differences in the amount of plowing. Both the plowing component of friction and the amplitude of stick-slip motion were determined to increase surface textures that promote plane strain conditions and decrease the textures that favor plane stress conditions.

scholarly journals Volcanic hydrothermal systems as potential analogues of Martian sulphate-rich terrains

2015 ◽  
Vol 95 (2) ◽  
pp. 153-169 ◽  
Author(s):  
A. Rodríguez ◽  
M.J. van Bergen
Keyword(s):  
Hydrothermal Activity ◽  
Hydrothermal Systems ◽  
Geothermal Systems ◽  
Ambient Conditions ◽  
Flow Paths ◽  
Near Surface ◽  
Mineral Associations ◽  
The Status ◽  
History Of ◽  
Active Processes

AbstractRemote sensing observations and rover missions have documented the presence of sulphate-rich mineral associations on Mars. Many of these minerals are paleo-indicators of hydrous, acidic and oxidising environments that must have prevailed in Mars´ distant past, contrary to the present conditions. Furthermore, occurrences of silica together with high Cl and Br concentrations in Martian soils and rocks represent fingerprints of chemically atypical fluids involved in processes operating on the surface or at shallow depth. From field observations at representative active volcanoes in subduction settings, supported by geochemical modelling, we demonstrate that volcanic hydrothermal systems are capable of producing Mars-like secondary mineral assemblages near lakes, springs and fumaroles through the action of acidic fluids. Water–gas-rock interactions, together with localised flow paths of water and fumarolic gas emitted from associated subaerial vents, lead to deposition of a range of sulphates, including gypsum, jarosite, alunite, epsomite and silica. Evaporation, vapour separation and fluid mixing in (near-) surface environments with strong gradients in temperature and fluid chemistry further promote the diversity of secondary minerals. The mineralogical and chemical marks are highly variable in space and time, being subject to fluctuations in ambient conditions as well as to changes in the status of volcanic-hydrothermal activity. It is concluded that active processes in modern volcanic-geothermal systems may be akin to those that created several of the sulphate-rich terrains in the early history of Mars.

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