Research on Reaction Mechanism of SiC and AlF3 in CO Atmosphere

2011 ◽  
Vol 233-235 ◽  
pp. 2610-2614
Author(s):  
Jia Ping Wang ◽  
Yong Li ◽  
Xiao Yan Zhu ◽  
Jun Bo ◽  
Jian Fang Zhang ◽  
...  
Keyword(s):  
High Temperature ◽  
Reaction Mechanism ◽  
Room Temperature ◽  
Aluminum Electrolysis ◽  
Experimental Results ◽  
Reaction Products ◽  
Operation Temperature ◽  
Electrolysis Cells ◽  
Major Reaction ◽  
Reaction Intensity

The reaction between SiC and AlF3 has been investigated in CO atmosphere at high temperature. Experimental results are shown that the reaction intensity between SiC and AlF3 is accelerated with the rise of temperature. At the temperature of 950 (aluminum electrolytic operation temperature is 935±15), the reaction intensity of SiC and AlF3 is not high and the major reaction products are SiF4 gas and Al4C3; Al4C3 occur severe hydration at room temperature which leads to the pulverization of specimens. The unexpected cells stop should try to be avoided or reduced during the usage of Si3N4-bonded SiC sidewall brick in aluminum electrolysis cells because of Al4C3 existents possibly.

Research on Reaction Mechanism of Si3N4 and AlF3 in CO Atmosphere

2011 ◽  
Vol 233-235 ◽  
pp. 2243-2251
Author(s):  
Jia Ping Wang ◽  
Yong Li ◽  
Xiao Yan Zhu ◽  
Ya Wei Zhai ◽  
Jun Bo ◽  
...  
Keyword(s):  
High Temperature ◽  
Reaction Mechanism ◽  
Aluminum Electrolysis ◽  
Experimental Results ◽  
Reaction Products ◽  
Operation Temperature ◽  
Electrolysis Cells ◽  
Aluminum Electrolyte

The reaction between Si3N4 and AlF3 had been investigated in CO atmosphere at high temperature. Experimental results are shown that the reaction between Si3N4 and AlF3 is accelerated with the rise of temperature. At the temperature of 950 (aluminum electrolytic operation temperature is 935±15), there is obvious reaction between Si3N4 and AlF3; under this experiment condition, Si3N4 converted into Si2N2O partly, Si2N2O can also react with AlF3. The reaction products of Si3N4 with AlF3 are SiF4 (g) and AlN, while the reaction products of Si2N2O with AlF3 are SiF4 (g) and Al8O3N6. So, during the usage of Si3N4-bonded SiC sidewall brick in aluminum electrolysis cells, the content of Si3N4 in Si3N4-SiC block are reduced which can bring down the corrosion of aluminum electrolyte to the sidewall materials.

The Ion Structure of NiFe2O4-10NiO-Based Cermet Anode in the Electrolyte

2018 ◽  
Vol 921 ◽  
pp. 119-127 ◽  
Author(s):  
Yuan Wang ◽  
Han Bing He
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Molten Salts ◽  
Large Scale ◽  
Room Temperature ◽  
Aluminum Electrolysis ◽  
Melting Process ◽  
Ion Structure ◽  
Inert Anodes ◽  
Complex Ion

The problem in the large-scale industrialization for aluminum electrolysis is the corrosion resistance of cermet inert anodes in high temperature molten salts. In this paper, the ion structure of NiFe2O4-10NiO-based cermet anode composition in the electrolyte was investigated. The experiment results show that Al-F and Al-O-F complex ion structures are produced at room temperature and perhaps Me-F (Me=Ni, Cu, Fe), Me-O-F or Me-Al-O-F are also formed. Moreover, Al-F and Al-O-F ion structures exist from room temperature to 700 °C and from 1050 °C to 1200 °C; In the rearrangement and melting process of molten salt at 800 °C -1000 °C, the ionic structures are mainly Al-O-F ions; Me-F and Me-O-F ion structures were not found at high temperature, this indicates that Al in Al-O-F complex ion structures is partially replaced by Fe, Ni or Cu to form MexAlaOyFz(z+2y-2x-3a)-.

Degradation of Reinforced Concrete Structures of Aluminum Electrolysis Plants Subjected to Elevated Temperature and Cyclic Load

2016 ◽  
Vol 711 ◽  
pp. 533-540
Author(s):  
Hideo Kasami ◽  
Takafumi Tayama
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Cyclic Load ◽  
Concrete Structures ◽  
Aluminum Electrolysis ◽  
Shear Cracks ◽  
Heavy Vehicles ◽  
Stray Current ◽  
Electrolysis Cells

Technical papers describing the temperature related degradation of concrete are abundant, and serious damages often occurred in concrete structures subjected to high temperature such as metallurgy factories, although such occurrences were seldom made public. Concrete structures in aluminum electrolysis plants are generally subjected to high temperature emitted from electrolysis cells and cyclic load of heavy vehicles. Besides, hydrogen fluoride emitted from cells and stray current through reinforcement may cause deteriorating effects. In the case of an electrolysis plant built in Niigata in late 1960's, a part of passageway slab collapsed within a year of operation. A few years later, mesh shaped cracks on operation floor and shear cracks on floor beams and columns were observed. And an overall investigation on floor beams of 4 smelter buildings was carried out to determine the extent of deterioration, in 1972. The residual strength decreased linearly with operation term. The extent of strength reduction in "t" years' operation that we named "Deterioration Factor" and limit of lifetime were estimated. Countermeasures to reduce cyclic load and to reinforce floor beams were then taken, as well as the application of the Deterioration Factor to the next electrolysis plant in Shikoku Island. Details of renewed design of S-Electrolysis Plant and degradation of concrete are discussed. These aluminum electrolysis plants in Niigata and Shikoku have stopped operation in 1985 due to the withdrawal of the refining company, and existing smelter buildings have been diverted to another use. Although this paper presents rather retrospective cases, the authors wish this would be still helpful as a case study on degradation in concrete structure due to elevated temperature.

scholarly journals Degradation of naturally produced hydroxylated polybrominated diphenyl ethers in Baltic Sea sediment via reductive debromination

2021 ◽  
Author(s):  
Dennis Lindqvist ◽  
Johan Gustafsson
Keyword(s):  
Baltic Sea ◽  
Polybrominated Diphenyl Ethers ◽  
Half Life ◽  
Room Temperature ◽  
Filamentous Algae ◽  
Reaction Products ◽  
Diphenyl Ethers ◽  
Major Reaction ◽  
Filamentous Macroalgae ◽  
High Concentrations

AbstractOver the last two decades, the occurrence of hydroxylated polybrominated diphenyl ethers (OH-PBDEs) has been observed to be nearly ubiquitous among Baltic Sea filamentous macroalgae. High concentrations are continuously recorded among red, green, and brown filamentous algae. Several of these algae species are ephemeral, and when large parts of the colonies decay at the end of their lifecycles, the OH-PBDEs are expected to largely partition to the sediment. In this study, the fate of OH-PBDEs in Baltic Sea sediment was investigated, with focus on the effect of reductive debromination. During chemical debromination, it was observed that the half-life could differ with as much as two orders of magnitude between a pentabrominated and a tetrabrominated congener. Using collected Baltic Sea sediment, it was further observed that the half-life of spiked pentabrominated OH-PBDEs spanned from a few days up to a few weeks in room temperature. At 4 °C, it took 6 months to achieve a 50% decrease in concentration of the fasted degrading congener. Clear differences in selectivity between chemical debromination and debromination in sediment were also observed when studying the major reaction products. Baltic Sea sediment seems to have a good capacity for reducing naturally produced OH-PBDEs.

scholarly journals Experimental Investigation of Electro-thermal Stress Impact on SiC-BJTs Electrical Characteristics

2013 ◽  
Vol 2013 (HITEN) ◽  
pp. 000290-000297
Author(s):  
Thibaut Chailloux ◽  
Cyril Calvez ◽  
Pascal Bevilacqua ◽  
Dominique Planson ◽  
Dominique Tournier
Keyword(s):  
Thermal Stress ◽  
High Temperature ◽  
Room Temperature ◽  
Thermal Stresses ◽  
Temperature Cycling ◽  
Bipolar Junction Transistors ◽  
Electrical Characteristics ◽  
Switching Operation ◽  
Operation Temperature ◽  
The Stability

The aim of this study consists in investigating the effects of electrical and thermal stresses on SiC n-p-n bipolar junction transistors (BJTs). The stability of the electrical characteristics of BJTs is inspected under switching operation, DC operation, temperature cycling and continuous thermal stress up to 225°C. While switching operation and temperature cycling for several hours lead to significant changes at 25°C, the electrical characteristics were little degraded at high temperature. Besides, DC operation and continuous thermal stress did not result in significant degradation at all, both at room temperature and at high temperature.

Analysis of a ceramic/metal laminate under thermal shock

2001 ◽  
Vol 16 (3) ◽  
pp. 753-764 ◽  
Author(s):  
D. Sherman ◽  
D. Schlumm
Keyword(s):  
High Temperature ◽  
Mechanical Strength ◽  
Thermal Shock ◽  
Room Temperature ◽  
Shock Loading ◽  
Structural Integrity ◽  
Experimental Results ◽  
High Mechanical Strength ◽  
Thermal Residual Stresses ◽  
Multilayered Systems

A ceramic/metal laminated system has lately been proposed by the authors. It is capable of maintaining high mechanical strength and structural integrity after high-temperature thermal shock. In this investigation, a multilayered, multimaterial system with strong interface, subjected to thermal shock loading, was analyzed. The analysis was based on a 1-D finite difference scheme and considers the thermal residual stresses. Using a failure criterion based on crack initiation, the number of broken layers due to thermal shock and the residual mechanical strength at room temperature was determined. A comparison with experimental results of three different lay-ups was made, demonstrating the ability of the program to predict the experimental results. The program was thus shown to be a significant tool for designing multimaterial multilayered systems for thermal shock applications.

scholarly journals Recent Advances in High Temperature Electrolysis Cells using LaGaO3-based Electrolyte

Ceramist ◽  
2021 ◽  
Vol 24 (4) ◽  
pp. 424-437
Author(s):  
Seokhee Lee ◽  
Sang Won Lee ◽  
Suji Kim ◽  
Tae Ho Shin
Keyword(s):  
High Temperature ◽  
High Performance ◽  
High Energy ◽  
Solid Oxide ◽  
Ion Conductor ◽  
Operation Temperature ◽  
High Efficient ◽  
Electrolysis Cells ◽  
Free Hydrogen ◽  
High Temperature Electrolysis

High temperature electrolysis is a promising option for carbon-free hydrogen production and huge energy storage with high energy conversion efficiencies from renewable and nuclear resources. Over the past few decades, yttria-stabilized zirconia (YSZ) based ion conductor has been widely used as a solid electrolyte in solid oxide electrolysis cells (SOECs). However, its high operation temperature and lower conductivity in the appropriate temperature range for solid electrochemical devices were major drawbacks. Regarding improving ionic-conducting electrolytes, several groups have contributed significantly to developing and applying LaGaO3 based perovskite as a superior ionic conductor. La(Sr)Ga(Mg)O3 (LSGM) electrolyte was successfully validated for intermediate-temperature solid oxide fuel cells (SOFCs) but was rarely conducted on SOECs for its high efficient electrolysis performance. Their lower mechanical strengths or higher reactivity with electrode compared with the YSZ electrolysis cells, which make it difficult to choose compatible materials, remain major challenges. In this field, SOECs have attracted a great attention in the last few years, as they offer significant power and higher efficiencies compared to conventional YSZ based electrolysers. Herein, SOECs using LSGM based electrolyte, their applications, high performance, and their issues will be reviewed.

High-Resolution Core Level Study of the Co/Si(111) Interface

1986 ◽  
Vol 83 ◽  
Author(s):  
F. Boscherini ◽  
J. J. Joyce ◽  
M. W. Ruckman ◽  
J. H. Weaver
Keyword(s):  
High Temperature ◽  
High Resolution ◽  
Schottky Barrier ◽  
Barrier Height ◽  
Room Temperature ◽  
Schottky Barrier Height ◽  
Core Level ◽  
Reaction Products ◽  
Semiconductor Structures ◽  
Epitaxial Interface

There has recently been considerable interest in the reaction between Co and a clean Si surface. This interest stems from the epitaxy of CoSi2 and NiSi2 on Si and its potential for the construction of reliable and stable metal-semiconductor structures. In fact, the fabrication of a Si/CoSi2/Si transistor has been recently reported.[l] On a more fundamental side, it has been possible to address the problem of the relation between Schottky barrier height and structure at the NiSi2/Ni interface, which exhibits both a rotated (B-type) and unrotated (A-type) geometry.[2] For CoSi2/Si only the 180° rotated, B-type disilicide is formed. By studying the room temperature interface, we have attempted to describe the nature and physical extent of reaction products; such knowledge is important to understand the formation of interface silicides which ultimately control the nature of the high temperature epitaxial interface.

High Temperature Superconductivity

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Andrew Jordan
Keyword(s):  
High Temperature ◽  
Liquid Helium ◽  
Room Temperature ◽  
Power Transmission ◽  
High Temperature Superconductivity ◽  
Experimental Results ◽  
Practical Applications ◽  
Magnetically Levitated

Superconductivity in liquid helium, a very cold substance, was discovered in 1908. Ever since, researchers have aimed to fabricate materials that exhibit superconductivity at room temperature, which would offer a host of practical applications, from lossless power transmission to magnetically levitated trains. Andrew Jordan examines recent experimental results published by Sven Badoux et al.

scholarly journals Recent Advances in High Temperature Electrolysis Cells using LaGaO3-based Electrolyte

Ceramist ◽  
2021 ◽  
Vol 24 (4) ◽  
pp. 424-437
Author(s):  
Seokhee Lee ◽  
Sang Won Lee ◽  
Suji Kim ◽  
Tae Ho Shin
Keyword(s):  
High Temperature ◽  
High Performance ◽  
High Energy ◽  
Solid Oxide ◽  
Ion Conductor ◽  
Operation Temperature ◽  
High Efficient ◽  
Electrolysis Cells ◽  
Free Hydrogen ◽  
High Temperature Electrolysis

High temperature electrolysis is a promising option for carbon-free hydrogen production and huge energy storage with high energy conversion efficiencies from renewable and nuclear resources. Over the past few decades, yttria-stabilized zirconia (YSZ) based ion conductor has been widely used as a solid electrolyte in solid oxide electrolysis cells (SOECs). However, its high operation temperature and lower conductivity in the appropriate temperature range for solid electrochemical devices were major drawbacks. Regarding improving ionic-conducting electrolytes, several groups have contributed significantly to developing and applying LaGaO3 based perovskite as a superior ionic conductor. La(Sr)Ga(Mg)O3 (LSGM) electrolyte was successfully validated for intermediate-temperature solid oxide fuel cells (SOFCs) but was rarely conducted on SOECs for its high efficient electrolysis performance. Their lower mechanical strengths or higher reactivity with electrode compared with the YSZ electrolysis cells, which make it difficult to choose compatible materials, remain major challenges. In this field, SOECs have attracted a great attention in the last few years, as they offer significant power and higher efficiencies compared to conventional YSZ based electrolysers. Herein, SOECs using LSGM based electrolyte, their applications, high performance, and their issues will be reviewed.

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