Effect of Surface Condition on Creep of Some Commercial Metals

1953 ◽  
Vol 20 (1) ◽  
pp. 30-32
Author(s):  
E. D. Sweetland ◽  
E. R. Parker
Keyword(s):  
Surface Layer ◽  
Creep Rate ◽  
Axial Stress ◽  
Surface Condition ◽  
Pure Copper ◽  
Inert Atmosphere ◽  
Oxide Surface ◽  
Secondary Creep ◽  
Before And After ◽  
Relative Creep

Abstract The relative creep rate of specimens of 2S aluminum and commercial drawn copper were investigated with the oxide surface layers removed and then, under the same conditions, after the oxide was permitted to form. The oxide was removed mechanically by stripping the test specimens in an inert atmosphere furnace so equipped that an axial stress could be applied and the creep rate determined without disturbing the atmosphere. After the oxide-free specimen was observed to be creeping essentially linearly with time (i.e., the quasiviscous, secondary creep range was established), air was admitted to the furnace. The extension versus time plot was continued after admission of air and the temperature held constant. Since all of the known parameters affecting creep rate (temperature, grain size, degree of work hardening, stress, and so on) except the gaseous environment were the same before and after admitting air, the effect of this change could be isolated. A decrease in creep rate was observed after air had been admitted to the furnace. These experimental results indicate that the presence of an oxide surface layer on the commercial grades of pure copper and aluminum increases the creep strength of these metals. The manner in which this relatively thin surface layer contributes to the strength of the parent metal is not clear, but the phenomenon is consistent with the theory of dislocations as presented by G. I. Taylor if it is assumed that the oxide inhibits the generation and/or migration of dislocations.

A Mössbauer study of spin-pinning in the oxide surface layer on fine iron particles

1992 ◽  
Vol 68 (1-4) ◽  
pp. 405-408
Author(s):  
Runsheng Huang ◽  
Hongqi Xiong ◽  
Qingyou Lu ◽  
Yuanfu Hsia ◽  
Rongchuan Liu ◽  
...  
Keyword(s):  
Surface Layer ◽  
Oxide Surface ◽  
Iron Particles ◽  
Mössbauer Study ◽  
Fine Iron

scholarly journals About the mechanism for reducing the adhesion wear of the copper friction pair in the inert atmosphere by the nitrogen ions implantation method

2020 ◽  
pp. 72-79
Author(s):  
V.P. Sergeev ◽  
◽  
M.P. Kalashnikov ◽  
A.R. Sungatulin ◽  
O.V. Sergeev ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Surface Layer ◽  
Friction Pair ◽  
High Energy ◽  
Inert Atmosphere ◽  
Solid Solution Hardening ◽  
Internal Stresses ◽  
Maximum Increase ◽  
Energy Beam ◽  
Nitrogen Ions

The mechanisms of increasing the resistance of copper samples treated with a high-energy beam of nitrogen ions to adhesive wear during friction together with a copper counterbody in an argon atmosphere are studied. It was shown that the increase in wear resistance is complex and is associated with the action of mechanisms such as solid-solution hardening, grinding of copper grains, precipitation of the finely dispersed CuN3 phase, increase in the density of dislocations and internal stresses of the second kind in the surface layer . The maximum increase in wear resistance and microhardness (~ 4 and ~ 2.6 times, respectively, compared with the original copper) is observed about ion fluence of ~ 9×1017 ion/cm2. A further increase in fluencies leads to a decrease in wear resistance and microhardness due to the enlargement of the pores formed in the surface layer of copper as a result of implantation of nitrogen ions.

scholarly journals Saline-sodic soil treated with gypsum, organic sources and leaching for successive cultivation of sunflower and rice

2019 ◽  
Vol 23 (12) ◽  
pp. 891-898 ◽  
Author(s):  
Petrônio D. dos Santos ◽  
Lourival F. Cavalcante ◽  
Hans R. Gheyi ◽  
Geovani S. de Lima ◽  
Everaldo M. Gomes ◽  
...  
Keyword(s):  
Surface Layer ◽  
Rice Husk ◽  
Rice Variety ◽  
Rice Cultivation ◽  
Exchangeable Sodium ◽  
Sodic Soils ◽  
Sodic Soil ◽  
Soil Layers ◽  
Before And After ◽  
Irrigated Perimeter

ABSTRACT Correction of saline and sodic soils aims to reduce salts dissolved in the solution and exchangeable sodium, respectively, to allow the growth and production of crops. In this context, an experiment was carried out between August/2011 and September/2012, in saline-sodic soil of the Irrigated Perimeter of São Gonçalo, in the municipality of Sousa, PB, Brazil. Agricultural gypsum, organic sources and continuous leaching for reducing salinity, sodicity and alkalinity in the saline-sodic soil and their effects on the production of the sunflower cultivar Embrapa 122/V-2000 and the rice variety Diamante were evaluated. The treatments were distributed in four randomized blocks and the soil was subjected to continuous leaching for 50 days and evaluated for salinity, sodicity and alkalinity before and after leaching, as well after sunflower and rice cultivation, in the 0-0.20 and 0.20-0.40 m layers. Leaching and the application of gypsum and organic sources reduced the initial salinity in both soil layers, to a greater extent in the surface layer. Exchangeable sodium decreased in 0-0.20 m and increased in 0.20-0.40 m. After rice cultivation, the soil in the 0-0.20 m layer changed from saline-sodic to non-saline in the treatments gypsum + bovine manure and gypsum + rice husk. The reduction of salinity, sodicity and alkalinity in the soil was higher during rice cultivation than during sunflower cultivation.

Evaluation of the Bioactivity Behavior of a 48 Wt %SiO2 Bioglass through Experiments in Simulated Body Fluid

2012 ◽  
Vol 727-728 ◽  
pp. 1238-1242 ◽  
Author(s):  
Roger Borges ◽  
Antônio Carlos da Silva ◽  
Juliana Marchi
Keyword(s):  
Corrosion Resistance ◽  
Surface Layer ◽  
Simulated Body Fluid ◽  
Body Fluid ◽  
Glass Network ◽  
In Vitro Experiments ◽  
High Corrosion Resistance ◽  
Before And After ◽  
O 19

Among bioceramics materials, bioglasses which exhibits either a bioactive or resorbable behavior has been studied for many applications, such as bone substitutive and regeneration. When in contact with body fluid, the bioglasses can induce the formation of a hydroxyapatite surface layer. In this paper, we studied the bioactivity of a bioglass containing 48 wt %SiO2, 27 wt% Na2O, 19 wt % CaO and 6 wt %P2O5. After fusion and annealing, the samples were immersed in SBF for different periods, up to 14 days. The samples were characterized through XRD, DRIFT and SEM before and after bioactivity experiments. The overall results suggest the formation of a surface layer of consisting of hydroxyapatite, which was crystallized within seven days after in vitro experiments, leading to a suitable bioactivity. Moreover, the samples showed a glass network with high cohesion due to calcium addition, leading to materials with high corrosion resistance.

Reprint of “Modification of the GaAs native oxide surface layer into the layer of the Ga2O3 dielectric by an Ar+ ion beam”

2018 ◽  
Vol 355 ◽  
pp. 297-300
Author(s):  
V.M. Mikoushkin ◽  
V.V. Bryzgalov ◽  
E.A. Makarevskaya ◽  
A.P. Solonitsyna ◽  
D.E. Marchenko
Keyword(s):  
Surface Layer ◽  
Ion Beam ◽  
Native Oxide ◽  
Oxide Surface

scholarly journals Effect of Ultrasonic Surface Rolling Treatment on Corrosion Behavior of Alloy 690

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 917 ◽  
Author(s):  
Jiang Liu ◽  
Junbiao Liu ◽  
Xuehui Zhang ◽  
Tahir Ahmad ◽  
Tongxiang Liang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Layer ◽  
Corrosion Behavior ◽  
Electrochemical Corrosion ◽  
Coarse Grained ◽  
Alloy 690 ◽  
Average Grain Size ◽  
Before And After ◽  
Immersion Experiment ◽  
Secondary Side

The nanograins (NG) on the top surface layer of alloy 690 were successfully prepared by ultrasonic surface rolling treatment (USRT). The average grain size of NG alloy 690 was 55 nm, and the thickness of the NG surface layer was about 1 μm. Meanwhile, the surface roughness was significantly reduced after surface nanocrystalliztion. The corrosion behavior of alloy 690 before and after USRT was studied in a secondary side environment containing chloride. Electrochemical corrosion experiments demonstrated that the passive film generated by USRT was denser than that formed on coarse-grained (CG) alloy 690. Pitting corrosion was prone to occur in grain boundaries of CG alloy 690, and the pits on the surface of NG alloy 690 were smaller than those generated on CG alloy 690 after 1000 h of an immersion experiment.

scholarly journals Production of Surface Layer with Gradient Microstructure and Microhardess on Copper by High Pressure Surface Rolling

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 73
Author(s):  
Juying Li ◽  
Qingsong Mei ◽  
Yana Li ◽  
Beihai Wang
Keyword(s):  
High Pressure ◽  
Surface Layer ◽  
Pure Copper ◽  
X Ray Diffraction ◽  
Electronic Microscopy ◽  
X Ray ◽  
Pressure Surface ◽  
Surface Gradient ◽  
Pressure Time ◽  
Gradient Microstructure

Pure copper was subjected to high-pressure surface rolling (HPSR) to obtain a surface gradient layer. Effects of HPSR parameters on the surface microstructure and microhardness of Cu were investigated by using optical microscopy, transmission electronic microscopy, X-ray diffraction, and the microhardness test. The HPSR surface layer has a gradient microstructure consisting of increasingly refined grains with decreasing depth from the treated surface (DFS). The thicknesses of the refined surface layer can be up to ~1.8 mm, and the grain size of the topmost surface is down to ~88 nm, depending on the HPSR parameters including pressure, time, and temperature. Microhardness of HPSR samples increases with decreasing DFS, with a maximum of ~2.4 times that of the undeformed matrix. The present results indicated that HPSR could be an effective method for the production of a mm-thick surface layer on Cu with gradient microstructure and property.

Finite Element Analysis of Creep Behavior of AZ91D Magnesium Matrix Composites Reinforced with Aluminum Silicate Short Fibers

2012 ◽  
Vol 568 ◽  
pp. 311-314
Author(s):  
Jun Tian ◽  
Shou Yan Zhong ◽  
Zi Qiong Shi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Creep Rate ◽  
Creep Behavior ◽  
Axial Stress ◽  
Short Fiber ◽  
Steady Creep ◽  
Element Analysis ◽  
Interface Module ◽  
The Impact

By Computer finite element analysis, the impact of the interface thickness, the interface module and the short fiber orientation of Al2O3-SiO2(sf)/AZ91D composite on the maximum fiber axial stress and the steady creep rate is studied. Maximum axial stress of the short fiber is in the fiber center, and the axial stress gradually decreases along the direction of the fiber length. When the external stress is constant, the maximum fiber axial stress increases with decreasing of the thickness of the interface, and the steady creep rate increases with the increasing of thickness of the interface. The maximum fiber axial stress increases with the increasing of the interface modulus, the increasing of the interface module improves the load transfer and the creep resistance. Finite element simulation results and experimental results can be well matched to better explain the creep behavior.

Influence of Silica Sand Particles on Disc Brake Squeal Noise

2013 ◽  
Vol 471 ◽  
pp. 81-85 ◽  
Author(s):  
Ahmad Razimi Mat Lazim ◽  
Abd Rahim Abu Bakar ◽  
Mohd Kameil Abdul Hamid ◽  
Izzat Mohd Asri
Keyword(s):  
Surface Condition ◽  
Surface Characteristics ◽  
Silica Sand ◽  
Brake Pad ◽  
Brake Squeal ◽  
The Road ◽  
Film Distribution ◽  
Before And After ◽  
Sand Particles ◽  
On The Road

Researchers in recent years begin to explore on tribological behavior of automotive brake squeal phenomena which covers the morphology, chemical composition, friction and wear, phase composition and third body or friction film distribution. However less effort has been made to study the tribological on the influence of small particles on brake squeal. During braking condition, both rotor and pads are exposed to road environmental particle which may affect pads surface condition. In order to assess the influence of this particle on brake squeal a series of squeal tests were performed. Silica sand grit particles with a size range between 400 to 200 μm which most available on the road surface were used in this experiment. Brake pad and disc surface characteristics were analyzed before and after squealing condition using Scanning Electron Microscope (SEM) and Energy dispersive X-ray analysis (EDX). The result shows that the silica sand particles had influence the squeal and surface behavior of the brake pad.

scholarly journals Influence of pre-existing microstructure on mechanical properties of marine ice during compression experiments

2014 ◽  
Vol 60 (221) ◽  
pp. 576-586 ◽  
Author(s):  
Marie Dierckx ◽  
Mark Peternell ◽  
Christian Schroeder ◽  
Jean-Louis Tison
Keyword(s):  
Rheological Properties ◽  
Rheological Behaviour ◽  
Secondary Creep ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Before And After ◽  
Weak Points ◽  
The Given ◽  
Shelf Flow ◽  
Range Of Values

AbstractMarine ice is an important component of ice shelves in Antarctica. It accretes in substantial amounts at weak points and below ice shelves. It is likely to exhibit peculiar rheological properties, which are crucial to understanding its potential role in stabilizing ice-shelf flow. Due to its location and consolidation processes, marine ice can present a variety of textures which are likely to influence its rheological properties. We present a new dataset of unconfined uniaxial compression experiments on folded marine ice samples that have been cut at various angles to the folds. Texture and fabric analyses are described ‘before’ and ‘after’ the deformation experiment. It is shown that, in the given stress configuration, the geometry of the anisotropy controls the rheological behaviour of the marine ice. During secondary creep, folded marine ice is harder to deform than weakly textured ice when compressed parallel or perpendicular to the folds' hinges, while the reverse is true for ice compressed at 45°. The observed range of values for the n exponent in Glen's flow law is between 2.1 and 4.1. Surprisingly, we see that tertiary creep tends to develop at a higher total strain than for randomly oriented impurity-free meteoric ice.

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