The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
J P Mccaffrey - One of the best experts on this subject based on the ideXlab platform.
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Surface Damage formation during ion beam thinning of samples for transmission electron microscopy
Ultramicroscopy, 2001Co-Authors: J P Mccaffrey, M W Phaneuf, L D MadsenAbstract:Abstract All techniques employed in the preparation of samples for transmission electron microscopy (TEM) introduce or include artifacts that can degrade the images of the materials being studied. One significant cause of this image degradation is Surface amorphization. The Damaged top and bottom Surface layers of TEM samples can obscure subtle detail, particularly at high magnification. Of the techniques typically used for TEM sample preparation of semiconducting materials, cleaving produces samples with the least Surface amorphization, followed by low-angle ion milling, conventional ion milling, and focused ion beam (FIB) preparation. In this work, we present direct measurements of Surface Damage on silicon produced during TEM sample preparation utilizing these techniques. The thinnest Damaged layer formed on a silicon Surface was measured as 1.5 nm thick, while an optimized FIB sample preparation process results in the formation of a 22 nm thick Damaged layer. Lattice images are obtainable from all samples.
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Surface Damage formation during ion beam thinning of samples for transmission electron microscopy
Ultramicroscopy, 2001Co-Authors: J P Mccaffrey, M W Phaneuf, L D MadsenAbstract:All techniques employed in the preparation of samples for transmission electron microscopy (TEM) introduce or include artifacts that can degrade the images of the materials being studied. One significant cause of this image degradation is Surface amorphization. The Damaged top and bottom Surface layers of TEM samples can obscure subtle detail, particularly at high magnification. Of the techniques typically used for TEM sample preparation of semiconducting materials, cleaving produces samples with the least Surface amorphization, followed by low-angle ion milling, conventional ion milling, and focused ion beam (FIB) preparation. In this work, we present direct measurements of Surface Damage on silicon produced during TEM sample preparation utilizing these techniques. The thinnest Damaged layer formed on a silicon Surface was measured as 1.5 nm thick, while an optimized FIB sample preparation process results in the formation of a 22 nm thick Damaged layer. Lattice images are obtainable from all samples.
L D Madsen - One of the best experts on this subject based on the ideXlab platform.
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Surface Damage formation during ion beam thinning of samples for transmission electron microscopy
Ultramicroscopy, 2001Co-Authors: J P Mccaffrey, M W Phaneuf, L D MadsenAbstract:Abstract All techniques employed in the preparation of samples for transmission electron microscopy (TEM) introduce or include artifacts that can degrade the images of the materials being studied. One significant cause of this image degradation is Surface amorphization. The Damaged top and bottom Surface layers of TEM samples can obscure subtle detail, particularly at high magnification. Of the techniques typically used for TEM sample preparation of semiconducting materials, cleaving produces samples with the least Surface amorphization, followed by low-angle ion milling, conventional ion milling, and focused ion beam (FIB) preparation. In this work, we present direct measurements of Surface Damage on silicon produced during TEM sample preparation utilizing these techniques. The thinnest Damaged layer formed on a silicon Surface was measured as 1.5 nm thick, while an optimized FIB sample preparation process results in the formation of a 22 nm thick Damaged layer. Lattice images are obtainable from all samples.
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Surface Damage formation during ion beam thinning of samples for transmission electron microscopy
Ultramicroscopy, 2001Co-Authors: J P Mccaffrey, M W Phaneuf, L D MadsenAbstract:All techniques employed in the preparation of samples for transmission electron microscopy (TEM) introduce or include artifacts that can degrade the images of the materials being studied. One significant cause of this image degradation is Surface amorphization. The Damaged top and bottom Surface layers of TEM samples can obscure subtle detail, particularly at high magnification. Of the techniques typically used for TEM sample preparation of semiconducting materials, cleaving produces samples with the least Surface amorphization, followed by low-angle ion milling, conventional ion milling, and focused ion beam (FIB) preparation. In this work, we present direct measurements of Surface Damage on silicon produced during TEM sample preparation utilizing these techniques. The thinnest Damaged layer formed on a silicon Surface was measured as 1.5 nm thick, while an optimized FIB sample preparation process results in the formation of a 22 nm thick Damaged layer. Lattice images are obtainable from all samples.
C Y Lim - One of the best experts on this subject based on the ideXlab platform.
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significance of non equilibrium grain boundaries in Surface Damage formation of ultrafine grained copper in high cycle fatigue
Scripta Materialia, 2007Co-Authors: Masahiro Goto, S Z Han, Seunghoe Kim, Norio Kawagoishi, C Y LimAbstract:High-cycle fatigue tests were carried out on specimens of ultrafine-grained copper both after equal channel angular pressing and after subsequent annealing at 160 °C for 3 min. The formation behavior of Surface Damage and the change in Surface hardness during stressing was monitored. A close relationship was observed between the change in hardness and the formation behavior of Surface Damage. The physical background for the formation of Surface fatigue Damage is discussed from the viewpoint of the non-equilibrium states of the microstructure.
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formation process of shear bands and protrusions in ultrafine grained copper under cyclic stresses
Scripta Materialia, 2006Co-Authors: Masahiro Goto, S Z Han, C Y Lim, T Yakushiji, S S KimAbstract:Abstract Ultrafine grained copper processed by equal channel angular pressing was fatigued at two constant stress amplitudes: σ a = 240 and 120 MPa (corresponding fatigue lives were N f ≑ 2 × 10 5 , and 4 × 10 6 cycles, respectively). Significant differences in the morphological features of post-fatigued Surfaces between the high and low cyclic stress amplitudes were observed. To clarify the formation process of the Surface Damage, the morphological changes in the Surface Damage caused by the cyclic stresses were monitored successively by an optical microscope. Putting the optical microscopy and scanning electron microscopy observations of the post-fatigued Surfaces together, the formation process of Surface Damage was discussed.
Masahiro Goto - One of the best experts on this subject based on the ideXlab platform.
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significance of non equilibrium grain boundaries in Surface Damage formation of ultrafine grained copper in high cycle fatigue
Scripta Materialia, 2007Co-Authors: Masahiro Goto, S Z Han, Seunghoe Kim, Norio Kawagoishi, C Y LimAbstract:High-cycle fatigue tests were carried out on specimens of ultrafine-grained copper both after equal channel angular pressing and after subsequent annealing at 160 °C for 3 min. The formation behavior of Surface Damage and the change in Surface hardness during stressing was monitored. A close relationship was observed between the change in hardness and the formation behavior of Surface Damage. The physical background for the formation of Surface fatigue Damage is discussed from the viewpoint of the non-equilibrium states of the microstructure.
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formation process of shear bands and protrusions in ultrafine grained copper under cyclic stresses
Scripta Materialia, 2006Co-Authors: Masahiro Goto, S Z Han, C Y Lim, T Yakushiji, S S KimAbstract:Abstract Ultrafine grained copper processed by equal channel angular pressing was fatigued at two constant stress amplitudes: σ a = 240 and 120 MPa (corresponding fatigue lives were N f ≑ 2 × 10 5 , and 4 × 10 6 cycles, respectively). Significant differences in the morphological features of post-fatigued Surfaces between the high and low cyclic stress amplitudes were observed. To clarify the formation process of the Surface Damage, the morphological changes in the Surface Damage caused by the cyclic stresses were monitored successively by an optical microscope. Putting the optical microscopy and scanning electron microscopy observations of the post-fatigued Surfaces together, the formation process of Surface Damage was discussed.
James L Howard - One of the best experts on this subject based on the ideXlab platform.
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the effects of trochlear design on Surface Damage and wear in retrieved total knee implants using profilometry
Orthopaedic Proceedings, 2018Co-Authors: J Matz, Brent A Lanting, Matthew G Teeter, James L HowardAbstract:IntroductionComplications related to the patellofemoral joint continue to be a substantial source of patient morbidity, causing anterior knee pain, instability, and dysfunction following total knee arthroplasty. One of the principle factors affecting patellofemoral outcomes may be trochlear design. The optimal design is currently unknown. The purpose of the present study was to study patellofemoral joint contact by analysing areas of wear in retrieved femoral components of three modern designs.Materials and MethodsEighteen retrieved femoral components featuring three different designs (constant radius of rotation, multiple radii of rotation, and multiple radii of rotation with built-in external rotation design) were matched on the basis of time-in-vivo, age, BMI and gender. All implants were cobalt chrome, posterior stabilized, cemented components with fixed bearing design with a reSurfaced patella. Trochlear wear and Surface Damage were assessed using visual inspection, low-magnification light microscopy...
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the effects of trochlear design on Surface Damage and wear in retrieved total knee implants using profilometry
Journal of Bone and Joint Surgery-british Volume, 2017Co-Authors: J Matz, Brent A Lanting, Matthew G Teeter, James L HowardAbstract:Introduction Complications related to the patellofemoral joint continue to be a substantial source of patient morbidity, causing anterior knee pain, instability, and dysfunction following total knee arthroplasty. One of the principle factors affecting patellofemoral outcomes may be trochlear design. The optimal design is currently unknown. The purpose of the present study was to study patellofemoral joint contact by analysing areas of wear in retrieved femoral components of three modern designs. Materials and Methods Eighteen retrieved femoral components featuring three different designs (constant radius of rotation, multiple radii of rotation, and multiple radii of rotation with built-in external rotation design) were matched on the basis of time-in-vivo, age, BMI and gender. All implants were cobalt chrome, posterior stabilized, cemented components with fixed bearing design with a reSurfaced patella. Trochlear wear and Surface Damage were assessed using visual inspection, low-magnification light microscopy, and light profilometry. Results Six implants from each group were successfully matched and were used for the topographical analysis. The femoral components were closely matched on the basis of time-in-vivo (TIV) (2.4 years±1.2), age (71.6 years±11.3), and BMI (33.0 kg/m2±7.0). There were 9 males and 9 females in the sample. Infection was the most common reason for revision (n=14) followed by instability (n=3) and loosening (n=1). There were no significant differences in TIV, age, and BMI between the groups (p=0.366, p=0.829, and p=0.586, respectively). When compared with unused, reference components, both the retrieved constant radius implants (p 0.05). Visual inspection of the femoral components showed evidence of Damage in all implant types. Modes of Damage included scratches, striation, pitting, and delamination. No significant differences between the groups were found with respect to overall Damage and wear on visual inspection (p=0.480). However, light profilometry analysis showed significantly increased roughness of multiple radii components compared to constant radius or multiple radii components with built-in external rotation (p<0.05). This was particularly significant in the proximal middle (p=0.045) and medial zones of the trochlea (p=0.017). Conclusions All retrieved femoral components show evidence of Damage in the trochlear area. While retrieved constant radius and multiple radii components showed increased wear compared to new components, retrieved components with multiple radii and built-in external rotation did not differ significantly from their new state. Retrieved multiple radii components appeared to have increased roughness compared with constant radius or multiple radii with built-in external rotation, particularly in the proximal zones of the trochlea. The long term effects of increased trochlear roughness requires further investigation and correlation with clinical outcomes. As the volume and patient demands for total knee arthroplasty increase, a greater understanding of the effect of trochlear design on clinical outcomes is warranted.
