High-Speed Growth of High-Quality 4H-SiC Bulk by Solution Growth Using Si-Cr Based Melt

2010 ◽  
Vol 645-648 ◽  
pp. 13-16 ◽  
Author(s):  
Katsunori Danno ◽  
Hiroaki Saitoh ◽  
Akinori Seki ◽  
H. Daikoku ◽  
Y. Fujiwara ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Speed ◽  
Grown Crystal ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Solution Growth ◽  
X Ray Diffraction ◽  
Large Crystal ◽  
X Ray ◽  
Basal Plane Dislocation

High-speed solution growth using Si-Cr based melt has been performed on on-axis 4H-SiC(0001) at a high temperature of about 2000°C. The maximum growth rate for one-hour growth reaches to 1120 m/h, while the typical growth rate of growth for 2h is about 500 m/h. A large crystal that is about 25 mm in diameter and 1650 m in thickness can be obtained by growth for 5h. The crystal quality is confirmed to be homogeneous by X-ray diffraction and X-ray topography, because FWHM is less than 30 arcsec. Etch pit density of the threading dislocations in the grown crystal is 103-104 cm-2, and that of basal plane dislocation is 2×102-3×103 cm-2. Resistivity of the crystals grown by the solution growth is comparable to those of crystals grown by physical vapor transport technique.

scholarly journals CRECIMIENTO DEL CORAL ACROPORA PALMATA (LAMARCK, 1886) EN EL PARQUE NACIONAL NATURAL CORALES DEL ROSARIO, CARIBE COLOMBIANO.

2016 ◽  
Vol 25 ◽  
Author(s):  
Rocío Del Pilar García U. ◽  
Elvira M. Alvarado Ch. ◽  
Alberto Acosta M.
Keyword(s):  
Growth Rate ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Annual Growth ◽  
Acropora Palmata ◽  
Alizarin Red ◽  
X Ray ◽  
Measuring Techniques ◽  
Growth Bands ◽  
Northern Zone

The growth rate in ten months (September 1992 - july 1993) for 30 colonies of Acropora palmata along the northern zone of the Corales del Rosario national natural park, Colombian Caribbean, was determined. Three measuring techniques were used: by hand, by staining with alizarin red, and from growth bands by X ray photography. The annual growth estimate for the species in the Park was 5.2 ± 1.3 cm and was found inversely correlated to the size of the colony (lenght, width and height). The growth presented a spatial variation. The smallest growth was found at Caleta Island and the largest at Caribaru Island. The maximum growth rate was observed in the dry season (December-February). No significant differences were found between measurement by hand and by alizarin red. The X-ray technique showed that Acropora palmata does not present discernible annual growth bands.

Growth and Study of Thick 3C-SiC Epitaxial Layers Produced by Epitaxy on 6H-SiC Substrates

2007 ◽  
Vol 556-557 ◽  
pp. 175-178 ◽  
Author(s):  
Alexander A. Lebedev ◽  
V.V. Zelenin ◽  
Pavel L. Abramov ◽  
Elena V. Bogdanova ◽  
Sergey P. Lebedev ◽  
...  
Keyword(s):  
Growth Rate ◽  
Detailed Analysis ◽  
Electronic Devices ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Epitaxial Layers ◽  
X Ray ◽  
Donor Acceptor ◽  
Pl Spectrum

3C-SiC epitaxial layers with a thickness of up to 100 μm and area of ~0.3-0.5 cm2 have been grown by sublimation epitaxy on hexagonal (6H-SiC) substrates at a maximum growth rate of about 200 μm per hour. The epilayers obtained are of n-type (Nd-Na ~ 1017 -1018 cm-3). According to X-ray data, the epitaxial layers are composed of the 3C-SiC polytype, without inclusions of other polytypes. The donor-acceptor (Al-N) recombination band with hνmax ~ 2.12 eV predominates in the photoluminescence (PL) spectrum. A detailed analysis of a PL spectrum measured at 6 K is presented. A conclusion is made that the epitaxial layers can be used as substrates for electronic devices based on 3C-SiC.

Crystalline Quality Evaluation of 6H-SiC Bulk Crystals Grown from Si-Ti-C Ternary Solution

2005 ◽  
Vol 483-485 ◽  
pp. 13-16 ◽  
Author(s):  
Kazuhiko Kusunoki ◽  
Kazuhito Kamei ◽  
Y. Ueda ◽  
S. Naga ◽  
Y. Ito ◽  
...  
Keyword(s):  
Grown Crystal ◽  
Seed Crystal ◽  
Solution Growth ◽  
Crystalline Quality ◽  
Ternary Solution ◽  
Bulk Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Koh Etching

The growth of 6H-SiC crystal from Si-Ti-C ternary solution was conducted under the temperature gradient and the crystalline quality evaluations of the grown crystals were carried out. 6H-SiC(0001) on-axis pvt-grown crystal was used as a seed crystal. Micropipes in the seed crystal were terminated during the solution growth and 28mm􀊷28mm self-standing micropipe-free SiC crystals were obtained. The quality of the grown crystals was investigated by SIMS, high-resolution x-ray diffraction and molten KOH etching. The content of residual impurities in the SiC were very low. The X-ray 􀐢-rocking curves of the solution grown SiC showed single peak with high peak intensity ,while that of the seed crystal showed several peaks due to the misoriented domains. Moreover, it was found that the number of etch-pit in the grown crystal is much less than that in the seed crystal and it decreases with the increase of the growth thickness. These results indicate that the crystalline quality of grown crystal was significantly improved during the solution growth.

Influence of a Scarfed Portal on the Compression Wave Generated by a High-Speed Train Entering a Tunnel

2005 ◽  
Vol 24 (4) ◽  
pp. 203-217 ◽  
Author(s):  
A. Winslow ◽  
M. S. Howe ◽  
M. Iida
Keyword(s):  
Growth Rate ◽  
Compression Wave ◽  
High Speed ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
High Speed Train ◽  
Wave Characteristics ◽  
Additional Improvement ◽  
Side Walls ◽  
Tunnel Entrance

An optimally designed entrance portal must be capable of minimizing the maximum growth rate of the compression wave generated when a high-speed train enters a tunnel. A theoretical and experimental investigation has been made to determine the changes in compression wave characteristics produced when the portal is ‘scarfed’ with tapering side walls. It is concluded that portal modifications of this type are unlikely to produce a significant reduction in the maximum compression wave growth rate. Small decreases in growth rate are possible (up to about 15%) for scarf walls extending a distance beyond the tunnel entrance of the order of the tunnel height, but little or no additional improvement is achieved with longer walls.

Solution Growth of Single Crystalline 6H-SiC from Si-Ti-C Ternary Solution

2007 ◽  
Vol 352 ◽  
pp. 89-94 ◽  
Author(s):  
Kenji Suzuki ◽  
Kazuhiko Kusunoki ◽  
Nobuyoshi Yashiro ◽  
Nobuhiro Okada ◽  
Kazuhito Kamei ◽  
...  
Keyword(s):  
Growth Rate ◽  
Single Crystal ◽  
High Growth ◽  
Graphite Crucible ◽  
High Growth Rate ◽  
Solution Growth ◽  
Ternary Solution ◽  
X Ray Diffraction ◽  
Growth Interface ◽  
X Ray

Solution growth of 6H-SiC single crystal from Si-Ti-C ternary solution using the accelerated crucible rotation technique (ACRT) was performed. The SiC growth rate exceeding 200 μm/hr was achieved in several ACRT conditions. Such a high growth rate can be ascribed to the enhancement of the carbon transport from the graphite crucible to the growth interface due to the use of the ACRT. The incorporation of inclusions of Si-Ti solvent in the grown SiC crystal was also significantly suppressed by using the ACRT. The intensive convection near the growth interface induced by the ACRT resulted in not only the marked increase of SiC growth rate but also the superior homogeneity in the surface morphology. It was concluded that faster stable growth could be accomplished in the SiC solution growth using the ACRT. The obtained SiC self-standing crystal exhibited homogeneous green colour without cracks and inclusions. We investigated the crystalline quality of the grown SiC crystal by means of X-ray diffraction. The, ω-scan rocking curves of (0006) reflection measured by X-ray diffraction provided the FWHM of 15-20 arc-second showing the excellent crystallinity of the solution grown 6H-SiC single crystal.

scholarly journals X-ray Determination of Compressive Residual Stresses in Spring Steel Generated by High-Speed Water Quenching

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1154
Author(s):  
Diego E. Lozano ◽  
George E. Totten ◽  
Yaneth Bedolla-Gil ◽  
Martha Guerrero-Mata ◽  
Marcel Carpio ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
High Speed ◽  
Spring Steel ◽  
X Ray Diffraction ◽  
Laboratory Equipment ◽  
X Ray ◽  
Water Chamber ◽  
Hardened Case ◽  
Compressive Residual Stresses

Automotive components manufacturers use the 5160 steel in leaf and coil springs. The industrial heat treatment process consists in austenitizing followed by the oil quenching and tempering process. Typically, compressive residual stresses are induced by shot peening on the surface of automotive springs to bestow compressive residual stresses that improve the fatigue resistance and increase the service life of the parts after heat treatment. In this work, a high-speed quenching was used to achieve compressive residual stresses on the surface of AISI/SAE 5160 steel samples by producing high thermal gradients and interrupting the cooling in order to generate a case-core microstructure. A special laboratory equipment was designed and built, which uses water as the quenching media in a high-speed water chamber. The severity of the cooling was characterized with embedded thermocouples to obtain the cooling curves at different depths from the surface. Samples were cooled for various times to produce different hardened case depths. The microstructure of specimens was observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) was used to estimate the magnitude of residual stresses on the surface of the specimens. Compressive residual stresses at the surface and sub-surface of about −700 MPa were obtained.

scholarly journals Fingerprinting shock-induced deformations via diffraction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Avanish Mishra ◽  
Cody Kunka ◽  
Marco J. Echeverria ◽  
Rémi Dingreville ◽  
Avinash M. Dongare
Keyword(s):  
High Speed ◽  
Shock Loading ◽  
Dislocation Slip ◽  
Line Profiles ◽  
X Ray Diffraction ◽  
Final State ◽  
X Ray ◽  
Shock Testing ◽  
Local Pressures ◽  
Deformation Modes

AbstractDuring the various stages of shock loading, many transient modes of deformation can activate and deactivate to affect the final state of a material. In order to fundamentally understand and optimize a shock response, researchers seek the ability to probe these modes in real-time and measure the microstructural evolutions with nanoscale resolution. Neither post-mortem analysis on recovered samples nor continuum-based methods during shock testing meet both requirements. High-speed diffraction offers a solution, but the interpretation of diffractograms suffers numerous debates and uncertainties. By atomistically simulating the shock, X-ray diffraction, and electron diffraction of three representative BCC and FCC metallic systems, we systematically isolated the characteristic fingerprints of salient deformation modes, such as dislocation slip (stacking faults), deformation twinning, and phase transformation as observed in experimental diffractograms. This study demonstrates how to use simulated diffractograms to connect the contributions from concurrent deformation modes to the evolutions of both 1D line profiles and 2D patterns for diffractograms from single crystals. Harnessing these fingerprints alongside information on local pressures and plasticity contributions facilitate the interpretation of shock experiments with cutting-edge resolution in both space and time.

Simulation and Experiment on the Residual Stress in Super-High Speed Grinding

2010 ◽  
Vol 135 ◽  
pp. 238-242
Author(s):  
Yue Ming Liu ◽  
Ya Dong Gong ◽  
Wei Ding ◽  
Ting Chao Han
Keyword(s):  
Residual Stress ◽  
High Speed ◽  
Element Model ◽  
Residual Stress Distribution ◽  
X Ray Diffraction ◽  
Machined Surface ◽  
X Ray ◽  
High Speed Grinding ◽  
Simulation And Experiment ◽  
Cylindrical Workpiece

In this paper, effective finite element model have been developed to simulation the plastic deformation cutting in the process for a single particle via the software of ABAQUS, observing the residual stress distribution in the machined surface, the experiment of grinding cylindrical workpiece has been brought in the test of super-high speed grinding, researching the residual stress under the machined surface by the method of X-ray diffraction, which can explore the different stresses from different super-high speed in actual, and help to analyze the means of reducing the residual stresses in theory.

AIN/GaN and AIGaN/GaN Heterostructures Grown by HVPE on SiC Substrates

1997 ◽  
Vol 482 ◽  
Author(s):  
Yu. V. Melnik ◽  
A. E. Nikolaev ◽  
S. I. Stepanov ◽  
A. S. Zubrilov ◽  
I. P. Nikitina ◽  
...  
Keyword(s):  
Growth Rate ◽  
Electron Beam ◽  
Vapor Phase ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Hydride Vapor Phase Epitaxy ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
X Ray ◽  
Micro Analysis

AbstractGaN, AIN and AIGaN layers were grown by hydride vapor phase epitaxy. 6H-SiC wafers were used as substrates. Properties of AIN/GaN and AIGaN/GaN structures were investigated. AIGaN growth rate was about 1 μm/min. The thickness of the AIGaN layers ranged from 0.5 to 5 μm. The AIN concentration in AIGaN layers was varied from 9 to 67 mol. %. Samples were characterised by electron beam micro analysis, Auger electron spectroscopy, X-ray diffraction and cathodoluminescence.Electrical measurements performed on AIGaN/GaN/SiC samples indicated that undoped AIGaN layers are conducting at least up to 50 mol. % of AIN.

A note on growth curves of rabbit lines selected on growth rate or litter size

1993 ◽  
Vol 57 (2) ◽  
pp. 332-334 ◽  
Author(s):  
A. Blasco ◽  
E. Gómez
Keyword(s):  
Growth Rate ◽  
Litter Size ◽  
Growth Curves ◽  
Live Weight ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Standard Errors ◽  
Adult Weight ◽  
Weight Growth ◽  
Using Data

Two synthetic lines of rabbits were used in the experiment. Line V, selected on litter size, and line R, selected on growth rate. Ninety-six animals were randomly collected from 48 litters, taking a male and a female each time. Richards and Gompertz growth curves were fitted. Sexual dimorphism appeared in the line V but not in the R. Values for b and k were similar in all curves. Maximum growth rate took place in weeks 7 to 8. A break due to weaning could be observed in weeks 4 to 5. Although there is a remarkable similarity of the values of all the parameters using data from the first 20 weeks only, the higher standard errors on adult weight would make 30 weeks the preferable time to take data for live-weight growth curves.

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