Interaction of a Sliding Wedge and a Metallic Specimen With a Near-Surface Inhomogeneity

2018 ◽  
Author(s):  
Vandana A. Salilkumar ◽  
Narayan K. Sundaram
Keyword(s):  
Sliding Wear ◽  
Surface Damage ◽  
Metal Substrate ◽  
Surface Plastic ◽  
Deformation Processing ◽  
Near Surface ◽  
Lagrangian Finite Element ◽  
Wedge Sliding ◽  
Metallic Specimen ◽  
Indenter Geometry

The problem of a hard wedge sliding against a metal substrate has been studied extensively for its importance in tribo-plasticity and deformation processing. Here we explore the effect of introducing a single, near-surface plastic inhomogeneity (termed as a pseudograin) in a metal substrate using Lagrangian finite element (FE) analysis. The pseudograin is allowed to be softer or harder than the surrounding material. The effects of sliding parameters like the size and location of the pseudograin, friction and indenter geometry are also studied. Interestingly, the introduction of the pseudograin can lead to production of surface folds / self-contacts, and acutely-inclined, near-surface, crack-like features, which cannot be reproduced by homogeneous specimens. In fact, this tribosystem is phenomenologically very rich, despite differing from classical triboplastic systems of Challen, Oxley and Torrance only by way of the inhomogeneity. Despite its simplicity, the model replicates several experimentally observed features of surface folding, and is a minimal model to obtain folding in sliding. The occurrence of surface folds and concomitant residual surface damage points to the important role played by microstructure-related inhomogeneities in determining surface quality in deformation processing operations (e.g. repeated sliding to generate UFG surfaces) and is also a potentially new mode of sliding wear.

Effect of Mn Modification on the Tribological Properties of In Situ Al-15Mg2Si Composites Containing Fe as an Impurity

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
A. Nadim ◽  
R. Taghiabadi ◽  
A. Razaghian
Keyword(s):  
Tribological Properties ◽  
Sliding Wear ◽  
Negative Impact ◽  
Wear Behavior ◽  
Harmful Effect ◽  
Chinese Script ◽  
Surface Plastic ◽  
Wear Properties ◽  
Near Surface

The effect of Mn modification on the tribological properties of Al-15Mg2Si-(0.5-2)Fe composites was investigated. The sliding wear tests were conducted under the applied pressures of 0.25, 0.5, and 1.0 MPa at the constant sliding speed of 0.13 m/s. According to the results, the behavior of FeMn-rich intermetallics against the strains induced by sliding wear has an important role in the wear behavior of composites. In low-Fe composites (0.5–1 wt % Fe), Mn promotes the formation of Chinese script α-Al15(Fe,Mn)3Si2 phases instead of harmful β-Al5FeSi platelets. The formation of these compounds strengthens the substrate and decreases its microcracking tendency giving rise to a more stable tribolayer and improved wear properties. At the higher Fe contents, Mn modification leads to the formation of primary polyhedral or star-like α-Al15(Fe,Mn)3Si2 compounds in the microstructure and substantially neutralizes the harmful effect of the primary β-Fe crystals on the wear behavior. However, when subjected to the friction-induced surface plastic strains, the near-surface α-FeMn particles fracture and incorporate into the tribolayer making it unstable and less protective. The tribolayer stability in Mn-modified composites decreases the chance of adhesion between contacting surfaces, and, under low applied pressures, lowers the average friction coefficient (AFC) and its fluctuation. At higher applied pressures, however, the nonmodified composites exhibit lower AFC, which is probably due to the negative impact of β-Fe fragments on the tribolayer shear strength.

Defects Introduced by Plasma Processing of Silicon

1992 ◽  
Vol 262 ◽  
Author(s):  
J. L. Benton
Keyword(s):  
Bulk Material ◽  
Surface Region ◽  
Surface Damage ◽  
Near Surface ◽  
Enhanced Diffusion ◽  
Interstitial Defect ◽  
Comprehensive Picture ◽  
Reaction Region ◽  
Defect Reactions ◽  
P Type

ABSTRACTThe electrical and optical properties of defects introduced by Reactive Ion Etching (RIE) in the near surface region of Si after dry etching with various gases and plasma conditions is studied with spreading Resistance (SR), photoluminescence (PL), and capacitance-voltage profiling (C-V). Plasma etching in chlorine and fluorine based gases produce donors at the surface in both n-type and p-type, Czochralski and float-zone silicon. Isochronal annealing reveals the presence of two distinct regions of dopant compensation. The surface damage region is confined to 1000 Å and survives heat treatment at 400°C, while the defect reaction region extends ≥ 1 μm in depth and recovers by 250°C. A comprehensive picture of the interstitial defect reactions in RIE silicon is completed. The interstitial defects, Ci and Bi, created in the ion damaged near surface region, undergo recombination enhanced diffusion caused by the presence of ultraviolet light in the plasma, resulting in the long range diffusion into the Si bulk. Subsequently, the interstitial atoms are trapped by the background impurities forming the defect pairs, CiOi, CSCi, or BiOi, which are observed experimentally. The depth of the diffusion-limited trapping and the probability of forming specific pairs depends on the relative concentrations of the reactants, oxygen, carbon or boron, present in the bulk material.

Automated Measurement of Near-Surface Plastic Shear Strain

2014 ◽  
Vol 3 (3) ◽  
pp. 1-16 ◽  
Author(s):  
G. Trummer ◽  
K. Six ◽  
C. Marte ◽  
A. Meierhofer ◽  
C. Sommitsch
Keyword(s):  
Shear Strain ◽  
Surface Plastic ◽  
Automated Measurement ◽  
Plastic Shear ◽  
Near Surface ◽  
Plastic Shear Strain

Low-energy Ion Scattering Measurement of Near-surface Damage Induced by the SiO2Dry-Etching Process

1998 ◽  
Vol 37 (Part 1, No. 4A) ◽  
pp. 2043-2050 ◽  
Author(s):  
Miyako Matsui ◽  
Fumihiko Uchida ◽  
Kiyomi Katsuyama ◽  
Takafumi Tokunaga ◽  
Masayuki Kojima
Keyword(s):  
Surface Damage ◽  
Low Energy ◽  
Etching Process ◽  
Ion Scattering ◽  
Near Surface ◽  
Low Energy Ion Scattering ◽  
Scattering Measurement

Ion Implantation Damage and Annealing in GaSb

1993 ◽  
Vol 316 ◽  
Author(s):  
S. Iyer ◽  
R. Parakkat ◽  
B. Patnaik ◽  
N. Parikh ◽  
S. Hegde
Keyword(s):  
Ion Implantation ◽  
Surface Damage ◽  
Liquid Nitrogen Temperature ◽  
Amorphous Layer ◽  
Implantation Technique ◽  
Near Surface ◽  
Projected Range ◽  
Implantation Damage ◽  
Pb Ions ◽  
Better Than

ABSTRACTIon implantation technique is being investigated as an alternate technique for doping GaSb. Hence an understanding of the production and removal of the damage is essential. In this paper, we report on the damages produced by implantation of Te, Er, Hg and Pb ions into undoped (100) GaSb single crystals and their recovery by Rutherford backscattering (RBS)/channeling. The implantations of 1013 to 1013 ions/cm2 in GaSb were done at liquid nitrogen temperature at energies corresponding to the same projected range of 447Å. A comparison of the damage produced by the different ions and their recovery was made by RBS/channeling along <100> axis of GaSb. Near surface damage equivalent to that of an amorphous layer was observed even at lower doses. Upon annealing at 600°C for 30 sec., the Te implanted samples showed best recovery compared to others (Xmin = 11%), the value of Xmin being better than those normally observed in unimplanted Te-doped substrates.

Time-Resolved and Post-Irradiation Studies of the Interaction of High-Power Pulsed Microwave Radiation with Silicon

1986 ◽  
Vol 74 ◽  
Author(s):  
R. B. James ◽  
P. R. Bolton ◽  
R. A. Alvarez ◽  
R. E. Valiga ◽  
W. H. Christie
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Surface Region ◽  
Surface Damage ◽  
Threshold Value ◽  
Optical Measurements ◽  
Time Resolved ◽  
Near Surface ◽  
Reflected Power ◽  
Secondary Ion

AbstractWe have measured the microwave-induced damage to the near-surface region of silicon for 1.9-μs pulses at a frequency of 2.856 GHz and a pulse power of up to 7.2 MW. Rectangular samples were irradiated in a test section of WR-284 waveguide that was filled with freon to a pressure of 30 psig. Incident, transmitted and reflected powers were monitored with directional couplers and fast diodes. The results of the time-resolved optical measurements show that the onset of surface damage is accompanied by a large increase in the reflected power. Examination of the irradiated surfaces shows that the degree of damage is greatest near the edges of the samples. Using secondary ion mass spectrometry to profile the implanted As, we find that the microwave pulses can melt the near-surface region of the material for pulse powers exceeding a threshold value.

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