Numerical Simulation of the Effects of Different Coatings on Graphite Susceptor for the Induction Process of Polycrystalline Silicon

2011 ◽  
Vol 704-705 ◽  
pp. 948-953
Author(s):  
K.L. Lian ◽  
S.S. Lian ◽  
S. Tsao
Keyword(s):  
Thermal Conductivity ◽  
Polycrystalline Silicon ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Heating Efficiency ◽  
Induction Process ◽  
Silicon Melt ◽  
The One ◽  
And Control ◽  
Graphite Susceptor

The vacuum induction melting and control solidification is a new developed process for the manufacture of polycrystalline silicon with the advantage of quick heating rate compared to the traditional resistance heating method. The graphite susceptor of the induction furnace plays a key role in controlling the temperature of the melt of polycrystal silicon for solar cells. This paper investigates how different coatings painted on the susceptor would influence the heating efficiency and the temperature distribution of the silicon melt. A graphite susceptor is usually coated with a thin film of insulating material to reduce heat losses and to prevent vapors such as SiO to contaminate the susceptor. Numerical simulations show that the coating material at the outer surface of the susceptor should be the one with low thermal conductivity to prevent heat loss. On the other hand, the coating on the inner surface should be the material with high thermal conductivity to allow easy heat transfer.

Modelling the Effects of Material Property and Dimension on the Heating of Silicon with Induction Directional Casting Furnace

2011 ◽  
Vol 479 ◽  
pp. 132-142
Author(s):  
K.L. Lian ◽  
Shuang Shii Lian ◽  
Y.H. Chen ◽  
S.C. Chu ◽  
Sheng Tsao
Keyword(s):  
Solar Cells ◽  
Temperature Distribution ◽  
Induction Heating ◽  
Material Properties ◽  
Polycrystalline Silicon ◽  
Great Influence ◽  
Base Plate ◽  
Processing Parameters ◽  
Silicon Melt ◽  
Graphite Susceptor

Directional Casting of silicon is a cost effective process to grow multi-crystalline Si ingots for wafers of solar cells. An appropriate melting process of polycrystalline silicon is closely related to the material properties and the size of graphite susceptors. These parameters have great influence not only on the melting temperature of silicon melt but also on the efficiency of induction heating, impurity distribution, dendrite and the direction of crystalline grains, which ultimately affect the properties of the solar cells. Therefore, in order to obtain good quality and energy efficiency of growth of polycrystalline silicon, one needs to know how the temperature fields relate to the processing parameters such as different sizes and properties of graphite susceptors in the furnace. In this paper, the influences of different properties such as density, electrical conductivity, thickness of graphite susceptor and cooling base-plate on the temperature of silicon with induction heating have been studied. To have an optimized control of processing parameters, a finite element-based software was used to simulate the temperature distribution of silicon melt in a polycrystalline vacuum induction refining furnace. The simulation takes into account the interaction of the induced eddy current and the heat transfer coupling in the vacuum induction furnace. Some of the modelling results are summarized as follows: 1. The material properties of the graphite susceptor have great influence on the temperature distribution. 2. The higher the operating frequency of the current, the sooner it reaches the melting temperature. 3. Base-plate made of stainless steel 304 performs better than the copper base-plate for the control of temperature distribution. 4. There exists an optimal thickness of the graphite susceptor, and the rise of temperature is not linearly proportional to the thickness of the graphite susceptor.

Excimer Laser Recrystallization of a-Si Employing Aluminum Masking Window

2000 ◽  
Vol 609 ◽  
Author(s):  
Jae-Hong Jeon ◽  
Min-Cheol Lee ◽  
Sang-Hoon Jung ◽  
Min-Koo Han
Keyword(s):  
Thermal Conductivity ◽  
Amorphous Silicon ◽  
Excimer Laser ◽  
Polycrystalline Silicon ◽  
Laser Recrystallization ◽  
Polycrystalline Silicon Films ◽  
And Control ◽  
Xecl Excimer Laser ◽  
High Reflectance ◽  
Lateral Heat

ABSTRACTA new excimer laser recrystallization method of amorphous silicon is proposed to increase the grain size and control the grain boundary locations in polycrystalline silicon films. The proposed method is based on the lateral grain growth which occurs at the interface between molten and unmolten regions. To obtain selectively molten regions, the proposed method employs aluminum patterns on amorphous silicon. The aluminum patterns act as the beam shield during the laser irradiation as well as the lateral heat sink during the solidification period. The high reflectance of aluminum at the wavelength of XeCl excimer laser offers stable beam shielding property, and the high thermal conductivity enhances the lateral heat flow by the quick draining of laterally propagated heat. TEM observation has revealed that the well arranged large grains were successfully obtained.

Microstructure in soft magnetic E3 (S1, Al) (Sendust) alloys

1988 ◽  
Vol 46 ◽  
pp. 770-771
Author(s):  
June D. Kim
Keyword(s):  
Electron Microscopy ◽  
Magnetic Properties ◽  
Ternary Phase Diagram ◽  
Vertical Tube ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Soft Magnetic ◽  
Quenching Temperature ◽  
Thin Foils ◽  
Vertical Tube Furnace

Iron-base alloys containing 8-11 wt.% Si, 4-8 wt.% Al, known as “Sendust” alloys, show excellent soft magnetic properties. These magnetic properties are strongly dependent on heat treatment conditions, especially on the quenching temperature following annealing. But little has been known about the microstructure and the Fe-Si-Al ternary phase diagram has not been established. In the present investigation, transmission electron microscopy (TEM) has been used to study the microstructure in a Sendust alloy as a function of temperature.An Fe-9.34 wt.% Si-5.34 wt.% Al (approximately Fe3Si0.6Al0.4) alloy was prepared by vacuum induction melting, and homogenized at 1,200°C for 5 hrs. Specimens were heat-treated in a vertical tube furnace in air, and the temperature was controlled to an accuracy of ±2°C. Thin foils for TEM observation were prepared by jet polishing using a mixture of perchloric acid 15% and acetic acid 85% at 10V and ∼13°C. Electron microscopy was performed using a Philips EM 301 microscope.

UDIMET 700

Alloy Digest ◽  
1987 ◽  
Vol 36 (1) ◽  
Keyword(s):  
Gas Turbines ◽  
Base Alloy ◽  
Heat Treating ◽  
Vacuum Arc ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Nickel Base Alloy ◽  
Vacuum Arc Remelting ◽  
Temperature Performance ◽  
Nickel Base

Abstract UDIMET 700 is a wrought nickel-base alloy produced by vacuum-induction melting and further refined by vacuum-arc remelting. It has excellent mechanical properties at high temperatures. Among its applications are blades for aircraft, marine and land-based gas turbines and rotor discs. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-51. Producer or source: Special Metals Corporation. Originally published March 1959, revised January 1987.

ALLVAC AC718

Alloy Digest ◽  
1991 ◽  
Vol 40 (7) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Heat Treating ◽  
Vacuum Arc ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Good Ductility

Abstract Allvac 718 is produced by vacuum induction melting followed by vacuum arc or electroslag consumable remelting. Th alloy has excellent strength and good ductility up to 1300 F (704 C). It also has excellent cryogenic properties. It has unique welding characteristics. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ni-394. Producer or source: Allvac Inc..

NICKELVAC N

Alloy Digest ◽  
1990 ◽  
Vol 39 (12) ◽  
Keyword(s):  
Solid Solution ◽  
Corrosion Resistance ◽  
Heat Treating ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Good Oxidation Resistance ◽  
Temperature Performance ◽  
Molten Fluoride ◽  
Fluoride Salts ◽  
Container Material

Abstract NICKEL VAC N was originally developed as a container material for molten fluoride salts. It is a moderate strength, solid solution strengthened alloy with good oxidation resistance to 1800 F. It has excellent resistance to fluoride salts in the range 1300-1600 F. It is produced by vacuum induction melting followed electroslag remelting. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ni-388. Producer or source: Teledyne Allvac.

NICKELVAC X-751

Alloy Digest ◽  
1990 ◽  
Vol 39 (11) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Aluminum Content ◽  
Heat Treating ◽  
Vacuum Arc ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Service Temperature ◽  
Maximum Service Temperature

Abstract NICKEL VAC X-751 is a modification of NICKEL VAC X-750 carrying higher aluminum content (0.90-1.50 vs 0.4-1.0%). This raises the maximum service temperature 100 F(55 C) to 1600 F(871 C). NICKEL VAC X-751 has a simplified and shortened heat treating cycle relative to NICKEL VAC X-750. It is produced by vacuum induction melting followed by vacuum arc or electroslag remelting. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ni-387. Producer or source: Teledyne Allvac.

UDIMET 90

Alloy Digest ◽  
1972 ◽  
Vol 21 (6) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Base Alloy ◽  
Heat Treating ◽  
Vacuum Arc ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Nickel Base Alloy ◽  
Vacuum Arc Remelting ◽  
Temperature Performance ◽  
Nickel Base

Abstract UDIMET 90 is a nickel-base alloy developed for elevated-temperature service. It is produced by vacuum induction melting and vacuum arc remelting techniques to develop optimum properties. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-174. Producer or source: Special Metals Corporation.

VASCOMAX T-300

Alloy Digest ◽  
1990 ◽  
Vol 39 (12) ◽  
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
High Temperature ◽  
Heat Treating ◽  
Vacuum Arc ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Vacuum Arc Remelting ◽  
Temperature Performance

Abstract VASCOMAX T-300 is an 18% nickel maraging steel in which titanium is the primary strengthening agent. It develops a tensile strength of about 300,000 psi with simple heat treatment. The alloy is produced by Vacuum Induction Melting/Vacuum Arc Remelting. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: SA-454. Producer or source: Teledyne Vasco.

An LQ Approach to Active Control of Vibrations in Helicopters

1996 ◽  
Vol 118 (3) ◽  
pp. 482-488 ◽  
Author(s):  
Sergio Bittanti ◽  
Fabrizio Lorito ◽  
Silvia Strada
Keyword(s):  
Optimal Control ◽  
Active Control ◽  
Linear Quadratic ◽  
Control Effort ◽  
Vibration Effect ◽  
Suitable Definition ◽  
Lq Optimal Control ◽  
The One ◽  
Definition Of ◽  
And Control

In this paper, Linear Quadratic (LQ) optimal control concepts are applied for the active control of vibrations in helicopters. The study is based on an identified dynamic model of the rotor. The vibration effect is captured by suitably augmenting the state vector of the rotor model. Then, Kalman filtering concepts can be used to obtain a real-time estimate of the vibration, which is then fed back to form a suitable compensation signal. This design rationale is derived here starting from a rigorous problem position in an optimal control context. Among other things, this calls for a suitable definition of the performance index, of nonstandard type. The application of these ideas to a test helicopter, by means of computer simulations, shows good performances both in terms of disturbance rejection effectiveness and control effort limitation. The performance of the obtained controller is compared with the one achievable by the so called Higher Harmonic Control (HHC) approach, well known within the helicopter community.

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