Increase in the Growth Rate by Rotating the Seed Crystal at High Speed during the Solution Growth of SiC

2014 ◽  
Vol 778-780 ◽  
pp. 63-66 ◽  
Author(s):  
Tomonori Umezaki ◽  
Daiki Koike ◽  
Atsushi Horio ◽  
S. Harada ◽  
Toru Ujihara
Keyword(s):  
Numerical Simulation ◽  
Growth Rate ◽  
Carbon Concentration ◽  
Concentration Gradient ◽  
High Speed ◽  
Rotation Speed ◽  
Seed Crystal ◽  
Solution Growth ◽  
Growth Interface ◽  
Wide Range

We studied the effect of rotation speed of seed crystal on the growth rate during the solution growth of SiC. The growth rate increased with increasing rotation speed of the seed crystal. The increase in the growth rate was observed in relatively wide range of carbon concentration. According to the numerical simulation, the carbon concentration gradient near the growth interface under 150 rpm condition is larger than 20 rpm (ACRT) condition. This indicates that increase in the growth rate is caused by the increase in the carbon concentration gradient of the diffusion layer.

The Effect of Stepped Wall of the Graphite Crucible in Top Seeded Solution Growth of SiC Crystal

2018 ◽  
Vol 924 ◽  
pp. 27-30
Author(s):  
Su Hun Choi ◽  
Young Gon Kim ◽  
Yun Ji Shin ◽  
Seong Min Jeong ◽  
Myung Hyun Lee ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Growth Rate ◽  
Temperature Distribution ◽  
Optical Microscopy ◽  
Single Crystals ◽  
Carbon Concentration ◽  
Graphite Crucible ◽  
Solution Growth ◽  
Metal Addition ◽  
Top Seeded Solution Growth

The crucible design having a stepped wall was introduced for increasing the growth rate of SiC crystal without metal addition in top-seeded solution growth (TSSG) method. The numerical simulation confirmed that new crucible design to increase the solvent-crucible interface could definitely change the temperature distribution and increase the carbon concentration. The simulation result, SiC single crystals were grown with Si solvent at 1900°C using a normal crucible and a stepped crucible to investigate the effect of crucible design having a stepped wall. Grown SiC layers were analyzed using Optical microscopy and Raman spectra. The growth rate in the stepped crucible was finally 66um/h observed.

scholarly journals Vibration of Rotating and Revolving Planet Rings with Discrete and Partially Distributed Stiffnesses

2020 ◽  
Vol 11 (1) ◽  
pp. 127
Author(s):  
Fuchun Yang ◽  
Dianrui Wang
Keyword(s):  
High Speed ◽  
Differential Operators ◽  
Natural Frequencies ◽  
Rotation Speed ◽  
Distribution Area ◽  
Vibration Modes ◽  
Governing Equations ◽  
Vibration Properties ◽  
Wide Range ◽  
Forced Responses

Vibration properties of high-speed rotating and revolving planet rings with discrete and partially distributed stiffnesses were studied. The governing equations were obtained by Hamilton’s principle based on a rotating frame on the ring. The governing equations were cast in matrix differential operators and discretized, using Galerkin’s method. The eigenvalue problem was dealt with state space matrix, and the natural frequencies and vibration modes were computed in a wide range of rotation speed. The properties of natural frequencies and vibration modes with rotation speed were studied for free planet rings and planet rings with discrete and partially distributed stiffnesses. The influences of several parameters on the vibration properties of planet rings were also investigated. Finally, the forced responses of planet rings resulted from the excitation of rotating and revolving movement were studied. The results show that the revolving movement not only affects the free vibration of planet rings but results in excitation to the rings. Partially distributed stiffness changes the vibration modes heavily compared to the free planet ring. Each vibration mode comprises several nodal diameter components instead of a single component for a free planet ring. The distribution area and the number of partially distributed stiffnesses mainly affect the high-order frequencies. The forced responses caused by revolving movement are nonlinear and vary with a quasi-period of rotating speed, and the responses in the regions supported by partially distributed stiffnesses are suppressed.

Vibration of High-Speed Compliant Gear Pairs

2016 ◽  
Author(s):  
Christopher G. Cooley ◽  
Robert G. Parker
Keyword(s):  
High Speed ◽  
Rotation Speed ◽  
Equations Of Motion ◽  
System Structure ◽  
Vibration Modes ◽  
Mesh Stiffness ◽  
Nodal Diameter ◽  
Gear Teeth ◽  
Wide Range ◽  
System Coupling

This study analytically investigates the vibration of high-speed, compliant gear pairs using a model consisting of coupled, spinning, elastic rings. The gears are elastically coupled by a space-fixed, discrete stiffness element that represents the contacting gear teeth. Hamilton’s principle is used to derive the nonlinear governing equations of motion and boundary conditions. These equations are linearized for small vibrations about the steady equilibrium due to rotation. The equations are cast in operator form, which exemplifies their gyroscopic system structure. The eigenvalue problem is discretized using Galerkin’s method. The natural frequencies and vibration modes for an example aerospace gear pair are numerically calculated for a wide-range of rotation speeds. The system coupling leads to multiple eigenvalue veering regions as the gear rotation speed varies. Highly coupled vibration modes that have meaningful deflection in the discrete mesh stiffness occur within a set frequency band. The vibration modes within this band have distinct nodal diameter components that evolve with rotation speed.

High-Speed Solution Growth of Single Crystal AlN from Cr-Co-Al Solvent

2016 ◽  
Vol 858 ◽  
pp. 1210-1213 ◽  
Author(s):  
Shota Watanabe ◽  
Masashi Nagaya ◽  
Yukihisa Takeuchi ◽  
Kenta Aoyagi ◽  
S. Harada ◽  
...  
Keyword(s):  
Growth Rate ◽  
Temperature Distribution ◽  
Numerical Analysis ◽  
Single Crystal ◽  
High Speed ◽  
Nitrogen Concentration ◽  
High Growth ◽  
High Growth Rate ◽  
Solution Growth ◽  
High Affinity

We achieved a high growth rate in solution growth of AlN single crystal by suppressing unintentional precipitations near the surface of solvent and by increasing the equilibrium nitrogen concentration in the solvent. In order to suppress unintentional precipitations, we made the solvent supersaturated just above the surface of the substrate by optimizing the composition of the solvent and the temperature distribution based on thermodynamic numerical analysis. In particular, we focused on interactions between nitrogen or aluminum and solvent elements, leading to the increase of the equilibrium nitrogen concentration. We selected chromium and cobalt due to their high affinity with nitrogen or aluminum. Consequently, we successfuly achieved growth rate as high as 200 μm/h in maximum.

Top-Seeded Solution Growth of 4H-SiC Bulk Crystal Using Si-Cr Based Melt

2012 ◽  
Vol 717-720 ◽  
pp. 61-64 ◽  
Author(s):  
Hironori Daikoku ◽  
M. Kado ◽  
H. Sakamoto ◽  
Hiroshi Suzuki ◽  
T. Bessho ◽  
...  
Keyword(s):  
Growth Rate ◽  
Seed Crystal ◽  
Solution Growth ◽  
Bulk Crystals ◽  
High Quality ◽  
Cross Sectional ◽  
Formation Technique ◽  
Top Seeded Solution Growth ◽  
Microscopy Images

We have grown high-quality long cylindrical (12 mm thick) 4H-SiC bulk crystals by the meniscus formation technique, which was first applied for the solution growth of bulk SiC. It enabled long-term growth by suppressing parasitic reactions such as polycrystal precipitation around the seed crystal. In addition, we could control the growth angle from −22° to 61° by adjusting the meniscus height. The thickness of the grown cylindrical crystals was 12 mm, which is the largest reported until now, and corresponded to a growth rate of 0.6 mm/h. Smooth morphology growth was maintained on the (000-1) C-face. In cross-sectional transmission optical microscopy images, few solvent inclusions and voids were observed. XRD measurements revealed that the FWHM values of the grown crystals were almost the same as those of the seed crystal.

Solution Growth of SiC Crystal with High Growth Rate Using Accelerated Crucible Rotation Technique

2006 ◽  
Vol 527-529 ◽  
pp. 119-122 ◽  
Author(s):  
Kazuhiko Kusunoki ◽  
Kazuhito Kamei ◽  
Nobuhiro Okada ◽  
Nobuyoshi Yashiro ◽  
Akihiro Yauchi ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Growth ◽  
Graphite Crucible ◽  
High Growth Rate ◽  
Solution Growth ◽  
Growth Interface ◽  
Rotation Technique ◽  
Stable Growth ◽  
Crucible Rotation ◽  
Carbon Transport

We performed solution growth of SiC single crystals from Si-Ti-C ternary solution using the accelerated crucible rotation technique (ACRT). It was confirmed that the growth rate exceeding 200 μm/hr was achievable by several ACRT conditions. This high growth rate might be due to the enhancement of the carbon transport from the graphite crucible to the growth interface using the ACRT. Moreover, the incorporation of inclusions of the Si-Ti solvent in the grown crystal was significantly suppressed by using the ACRT. It was thought that the intensive convection near the growth interface 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 can be accomplished in the SiC solution growth using the ACRT.

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 Experiments and Numerical Simulation of Performances and Internal Flow for High-Speed Rescue Pump with Variable Speeds

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Yuxing Bai ◽  
Fanyu Kong ◽  
Fei Zhao ◽  
Jiaqiong Wang ◽  
Bin Xia ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
High Power ◽  
High Speed ◽  
Rotation Speed ◽  
Low Frequency ◽  
Pressure Rise ◽  
Internal Flow ◽  
Simulation Method ◽  
Commercial Code ◽  
Frequency Components

The model pump is a high-speed, high-power pump designed to achieve rapid mine flooding rescue. This study conducted experiments to investigate pump performance curves, including head, efficiency, and power for the following six different rotation speeds: 3000, 3600, 4200, 4800, 5400, and 6000 rpm. Then, the numerical simulation method based on computational fluid dynamics commercial code Ansys was used to present the internal flow of the pump for the six different rotation speeds through steady and unsteady analyses. Results show that the numerical results agree well with experimental data. The designs of outlet and inlet angles of the impeller match each other well at high rotation speeds. The pressure pulsation coefficient Cp in the impeller and the diffuser channel remain constant at the same monitor point under different rotation speed conditions. The varying trend of the pressure-augmented coefficient ΔP indicates that, with the increase in rotation speed, the effect on pressure rise induced by the back part of the impeller channel is more evident than that by the front part. Also, the main frequency components of ΔP are concentrated on the region with low frequency. Moreover, the rotation speed has no significant effect on ΔP in the diffuser region. This study provides effective guidance and valuable reference for the design of high-speed, high-power pumps.

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.

Sign in / Sign up

Export Citation Format

Share Document