scholarly journals Effect of Argon Flow on Oxygen and Carbon Coupled Transport in an Industrial Directional Solidification Furnace for Crystalline Silicon Ingots

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 421
Author(s):  
Xiaofang Qi ◽  
Yiwen Xue ◽  
Wenjia Su ◽  
Wencheng Ma ◽  
Lijun Liu
Keyword(s):  
Directional Solidification ◽  
Flow Rate ◽  
Crystalline Silicon ◽  
Coupled Transport ◽  
Argon Flow Rate ◽  
Argon Gas ◽  
Argon Flow ◽  
Silicon Melt ◽  
Solidification Furnace ◽  
Evaporation Flux

Transient global simulations were carried out to investigate the effect of argon flow on oxygen and carbon coupled transport in an industrial directional solidification furnace for quasi-single crystalline silicon ingots. Global calculation of impurity transport in the argon gas and silicon melt was based on a fully coupled calculation of the thermal and flow fields. Numerical results show that the argon flow rate affects the flow intensity along the melt–gas surface, but has no significant effect on the flow patterns of silicon melt and argon gas above the melt–gas surface. It was found that the evaporation flux of SiO along the melt–gas surface decreases with the increasing argon flow rate during the solidification process. However, the net flux of oxygen atoms (SiO evaporation flux minus CO dissolution flux) away from the melt–gas surface increases with the increasing argon flow rate, leading to a decrease in the oxygen concentration in the grown ingot. The carbon concentration in the grown ingot shows an exponential decrease with the increase of the argon flow rate, owing to the fact that the dissolution flux of CO significantly decreases with the increasing argon flow rate. The numerical results agree well with the experimental measurements.

Temperature Distribution of Multi-Crystalline Silicon Ingots in the Directional Solidification Process

2013 ◽  
Vol 690-693 ◽  
pp. 977-980
Author(s):  
Xiang Rong Ma ◽  
Wu Zan ◽  
Xin Liang Zhang
Keyword(s):  
Temperature Distribution ◽  
Directional Solidification ◽  
Crystalline Silicon ◽  
Solidification Process ◽  
Casting Process ◽  
System Optimization ◽  
Silicon Melt ◽  
Solidification Furnace ◽  
Essential Knowledge ◽  
Melt Solidification

In order to better understand the casting process, we carried out global simulations of heat transfer to investigate the temperature distributions in furnace at 80 mm of insulation cage elevation and 40% of silicon melt solidification for multi-crystalline silicon (mc-Si) ingot using an industrial directional solidification furnace capable of producing 500 kg silicon ingot. The effect of heater position and the crystallization state of silicon melt on temperature distribution and interface shape are discussed as well to provide the essential knowledge for system optimization.

scholarly journals Behavior Characteristics of Argon Bubbles on Inner Surface of Upper Tundish Nozzle during Argon Blowing Process

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 590 ◽  
Author(s):  
Yang Li ◽  
Changgui Cheng ◽  
Minglei Yang ◽  
Zhixuan Dong ◽  
Zhengliang Xue
Keyword(s):  
Flow Rate ◽  
Casting Speed ◽  
Influence Factors ◽  
Gas Bubbles ◽  
Water Model ◽  
Argon Flow Rate ◽  
Argon Gas ◽  
Argon Flow ◽  
Inner Surface ◽  
Behavior Characteristics

During continuous casting of aluminum-killed steel, clogging of tundish nozzle frequently occurs, which seriously disrupts the normal casting sequences and deteriorates strand quality. Generally, argon blowing technology in the form of a stable and continuous argon film on the inner surface of the upper nozzle is employed to prevent the upper nozzle from clogging in the production. To explore the formation mechanism and influence factors of this argon film, a water model of the upper nozzle with blowing argon with a similarity ratio of 1:1 was built. The results show that the number of bubble chains increases gradually with increasing argon flow rate and casting speed, and the argon gas curtain appears at the bottom half of the upper nozzle. For a given argon flow rate, the velocity of argon gas bubbles increased gradually with increasing casting speed, and decreased gradually with increasing distance from the upper nozzle top. For a given casting speed, the average velocity of argon gas bubbles was largest at a distance from the upper nozzle top of 6 mm with argon flow rate of 150 L/h. The results could provide theoretical and technical basis for the optimization of blowing argon parameters in order to prevent the clogging of upper nozzle and improve strand quality.

PHOTO-CATALYTIC ACTIVITY AND PHOTO-ABSORPTION OF PLASMA-SPRAYED NANO-STRUCTURED TiO2 COATINGS

2010 ◽  
Vol 24 (31) ◽  
pp. 6115-6127 ◽  
Author(s):  
MARYAMOSSADAT BOZORGTABAR ◽  
MEHDI SALEHI ◽  
MOHAMMADREZA RAHIMIPOUR ◽  
MOHAMMADREZA JAFARPOUR
Keyword(s):  
Catalytic Activity ◽  
Flow Rate ◽  
Test Chamber ◽  
Catalytic Efficiency ◽  
Surface Characteristics ◽  
Catalytic Performance ◽  
Atmospheric Plasma ◽  
Argon Flow Rate ◽  
Photo Catalytic Activity ◽  
Argon Flow

Titanium dioxide coatings were deposited by utilizing atmospheric plasma-spraying system. The agglomerated P25/20 nano-powder and different spraying parameters (e.g., Argon flow rate and spray distance) were used to determine their influences on the microstructure, crystalline structure, photo-absorption, and photo-catalytic performance of the coatings. The microstructure and phases of as-sprayed TiO 2 coatings were characterized by scanning electron microscope SEM and X-ray diffraction, respectively. Surface characteristics were investigated by Fourier Transform Infrared. Photo-catalytic efficiency of the elaborated samples was also determined in an environmental test chamber set-up and evaluated from the conversion rate of ethanol. The photo-absorption was determined by UV–Vis spectrophotometer. The as-sprayed TiO2 coating was photo-catalytically reactive for the degradation of ethanol. The photo-catalytic activity was influenced by spray conditions. It is found that the photo-catalytic activity is significantly influenced by anatase content, surface area, and surface state. The results showed that the argon flow rate has an influence on the microstructure, anatase content, and photo-catalytic activity of the TiO 2 coatings.

scholarly journals Physical Simulation of Molten Steel Homogenization and Slag Entrapment in Argon Blown Ladle

Processes ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 479 ◽  
Author(s):  
Yang ◽  
Jin ◽  
Zhu ◽  
Dong ◽  
Lin ◽  
...  
Keyword(s):  
Flow Rate ◽  
Molten Steel ◽  
Physical Simulation ◽  
Mixing Time ◽  
Water Model ◽  
Steel Ladle ◽  
Argon Flow Rate ◽  
Argon Flow ◽  
Slag Thickness ◽  
Slag Entrapment

Argon stirring is one of the most widely used metallurgical methods in the secondary refining process as it is economical and easy, and also an important refining method in clean steel production. Aiming at the issue of poor homogeneity of composition and temperature of a bottom argon blowing ladle molten steel in a Chinese steel mill, a 1:5 water model for 110 t ladle was established, and the mixing time and interface slag entrainment under the different conditions of injection modes, flow rates and top slag thicknesses were investigated. The flow dynamics of argon plume in steel ladle was also discussed. The results show that, as the bottom blowing argon flow rate increases, the mixing time of ladle decreases; the depth of slag entrapment increases with the argon flow rate and slag thickness; the area of slag eyes decreases with the decrease of the argon flow rate and increase of slag thickness. The optimum argon flow rate is between 36–42 m3/h, and the double porous plugs injection mode should be adopted at this time.

Process Engineering of Dimensional Fused Silica Etching

2016 ◽  
Vol 870 ◽  
pp. 20-25 ◽  
Author(s):  
N.A. Shaburova ◽  
T.D. Ratmanov ◽  
D.D. Larionov
Keyword(s):  
Flow Rate ◽  
Fused Silica ◽  
Internal Stresses ◽  
X Ray Diffraction ◽  
Argon Flow Rate ◽  
Argon Flow ◽  
Barrier Coating ◽  
Zero Stresses ◽  
Internal Strains

The process of dimensional fused silica etching was offered. The production process of molycoat by magnetron sputtering of molybdenum target in inert gas (Argon) on vacuum distillation unit (NIKA-2012 TN) was examined. The coat quality (delamination, discontinuity) was analyzed; the influence of the first kind internal strains on the type of the observed defects was determined. The research was conducted by means of microscopic and X-ray diffraction analysis. It has been established that the internal strain value in the coat depends on the sputtering gas (Argon) flow rate, and, consequently, its pressure in the magnetron system for molybdenum sputtering. Zero stresses are registered under Argon's flow rate, which is 7.5 L/h. Influence of internal stresses level in the barrier coating on the quality of etching dimple.

Study on Amplitude of the Surface of Liquid Steel in Bottom-Blowing Ladle with Immersed Tube

2013 ◽  
Vol 734-737 ◽  
pp. 1511-1515
Author(s):  
De Hui Zhang ◽  
Ming Gang Shen ◽  
Qing Hua Qi ◽  
Jin Wei Kuang
Keyword(s):  
Flow Rate ◽  
Molten Steel ◽  
Liquid Steel ◽  
Similarity Theory ◽  
Steel Slag ◽  
Water Model ◽  
Argon Flow Rate ◽  
Steel Making ◽  
Argon Flow ◽  
Bottom Blowing

In the process of bottom argon blowing large argon flow rate can cause vigorous fluctuations on the surface of the molten steel and splash and reoxidize the molten steel, making the slag rolled into the steel slag, also causing the erosion of the ladle lining refractories. A 1:7 ratio ladle water model system of 150 ton ladle was established from the similarity theory in the lab. Study and analyze the effects of the inserting depth and diameter of immersed tube and bottom blowing flow rate on the fluctuation of the surface of liquid steel. Results show that the fluctuations on the surface of steel can be limited effectively by changing the diameter and inserted depth of immersed tube when selecting a larger flow rate of bottom blowing, which improve the mixing effect of liquid steel.

scholarly journals Changes in the Coating Composition Due to APS Process Conditions for Al2O3-Cr2O3-TiO2 Ternary Powder Blends

2020 ◽  
Author(s):  
Maximilian Grimm ◽  
Susan Conze ◽  
Lutz-Michael Berger ◽  
Gerd Paczkowski ◽  
Rico Drehmann ◽  
...  
Keyword(s):  
Flow Rate ◽  
Particle Temperature ◽  
Atmospheric Plasma ◽  
Ternary Blend ◽  
Process Conditions ◽  
Average Particle ◽  
Argon Flow Rate ◽  
Argon Flow ◽  
Coating Composition ◽  
Powder Blends

AbstractThermally sprayed coatings from the single oxides and binary compositions of the Al2O3-Cr2O3-TiO2 system show multifunctional properties. Ternary compositions are promising for further improvement in their performance. The stability of the composition during coating formation is an important issue for blended feedstock powders in order to obtain the desired properties. This work focuses on the compositional changes of a ternary blend of Al2O3, Cr2O3 and TiOx powders of equal content by mass in a conventional atmospheric plasma spraying (APS) process using an Ar/H2 plasma gas mixture. By increasing the argon flow rate at constant hydrogen flow rate, the total plasma gas flow rate and the Ar/H2 ratio were varied. For the highest argon flow rate, this resulted in an average particle velocity of 140% and an average particle temperature of 90% of the initial values, respectively. Coating composition and microstructure were studied by optical microscopy, SEM, including EDS analyses, and XRD. In addition, the coating hardness and electrical impedance were also measured. Differences in the “difficulty of melting factor” (DMF) and the thermal diffusivity of the three oxides appear to be responsible for the dramatic change of the coating composition with an increasing argon flow rate. For the highest argon flow rate applied, besides TiO2, the coating contains only 8 wt.% Al2O3, while the Cr2O3 content remained almost constant. At the same time, the change of the Ar/H2 ratio resulted in the formation of stoichiometric TiO2 in the coating by oxidation of TiOx in the feedstock powder. Moreover, a small content of titanium was found in the Cr2O3 splats, showing that there are only limited interactions between the large oxide powder particles. Thus, the study has shown that stability of the chemical composition during spraying of ternary powder blends is strongly influenced by the process conditions.

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