PHYSICAL-CHEMICAL ASSESSMENT OF SILICON CARBIDE – PRODUCT OF TECHNOGENIC SILICA RECOVERY BY FUME LIGNITE SEMI-COKE

Experimental data of formation laser-induced filaments in various media (potassium chloride, water, air and silicon carbide) are represented. These phenomena are analyzed as processes of Nonlinear and Relaxed Optics. Problems of modeling the creation the volume laser-induced filaments are investigated. Comparative analysis of plasma, nonlinear optical, diffractive and interference phenomena (including diffractive stratification), shocking processes (including Cherenkov radiation) and physical-chemical processes (including cascade model of excitation the proper chemical bonds in the regime of saturation the excitation), methods and models are represented and discussed. The optical breakdown for various matters has various natures: from shock ionization of gas to disruption of all chemical bonds for solid in the region of interaction light and matter or from nonequilibrium radiated processes in gas and liquid to irreversible phase transformations in solid. For diffraction stratification the modified models of Rayleygh rings was used. We show that this model allow to explain the experimental data for silicon carbide more effectively as Lugovoy-Prokhorov theory of moving foci. Modified Niels and Aage Bohrs models (microscopic) and Golub model (macroscopic) of Cherenkov radiation were used for the explanation of generation continuous radiation. Diffraction stratification shows the surface conic nature of Cherenkov radiation. It was show that physical-chemical method of estimations of corresponding processes is more general as electromagnetic (Kerr media) and one allow explain basic terms of resulting chain process with united point of view. Modified I. Frank model of interference the Cherenkov radiation was used for the explanation laser-induced optical breakdown in silicon carbide. Modified Rayleygh model and methods of continuum mechanics was created and used for the estimation sizes and form of observing nanovoids of silicon carbide. In whole the represented models allow to explain the corresponding chain more fuller and really as other models because one take into account of nonlinear optical transformation of primary laser radiation.

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Dependence of Silicon Carbide Product Morphology on the Degree of Mechanical Activation

Journal of the American Ceramic Society ◽

10.1111/j.1151-2916.2002.tb00157.x ◽

2004 ◽

Vol 85 (3) ◽

pp. 709-711 ◽

Cited By ~ 8

Author(s):

Leon L. Shaw ◽

Zhenguo Yang ◽

Ruiming Ren

Keyword(s):

Silicon Carbide ◽

Mechanical Activation ◽

Product Morphology ◽

Carbide Product

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Irradiation behavior of pyrolytic silicon carbide

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074288 ◽

1983 ◽

Vol 41 ◽

pp. 72-73

Author(s):

R. J. Lauf

Keyword(s):

Silicon Carbide ◽

Fission Products ◽

Thermodynamics And Kinetics ◽

Neutron Fluences ◽

Fuel Particles ◽

Sic Coatings ◽

Irradiation Behavior ◽

Kinetics Of ◽

Htgr Fuel

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain a layer of pyrolytic silicon carbide to act as a miniature pressure vessel and primary fission product barrier. Optimization of the SiC with respect to fuel performance involves four areas of study: (a) characterization of as-deposited SiC coatings; (b) thermodynamics and kinetics of chemical reactions between SiC and fission products; (c) irradiation behavior of SiC in the absence of fission products; and (d) combined effects of irradiation and fission products. This paper reports the behavior of SiC deposited on inert microspheres and irradiated to fast neutron fluences typical of HTGR fuel at end-of-life.

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Transmission Electron Microscopy of Protein Macromolecules

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066176 ◽

1971 ◽

Vol 29 ◽

pp. 424-425

Author(s):

Henry S. Slayter

Keyword(s):

Biological Systems ◽

Metal Vapor ◽

Resolving Power ◽

Electron Microscopic ◽

Chemical Methods ◽

Molecular Weights ◽

The Past ◽

Physical Chemical ◽

Transmission Electron

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

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Microstructural Evaluation of Silicon Carbide Whisker Reinforced Alumina Fabricated with Carbon-Coated Whiskers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100088919 ◽

1991 ◽

Vol 49 ◽

pp. 920-921

Author(s):

K. B. Alexander ◽

P. F. Becher

Keyword(s):

Silicon Carbide ◽

High Resolution Electron Microscopy ◽

Ceramic Composites ◽

Interface Debonding ◽

Resolution Electron ◽

Microstructural Evaluation ◽

Carbon Coated ◽

Electron Energy Loss ◽

Interfacial Films ◽

Debonding Process

The presence of interfacial films at the whisker-matrix interface can significantly influence the fracture toughness of ceramic composites. The film may alter the interface debonding process though changes in either the interfacial fracture energy or the residual stress at the interface. In addition, the films may affect the whisker pullout process through the frictional sliding coefficients or the extent of mechanical interlocking of the interface due to the whisker surface topography.Composites containing ACMC silicon carbide whiskers (SiCw) which had been coated with 5-10 nm of carbon and Tokai whiskers coated with 2 nm of carbon have been examined. High resolution electron microscopy (HREM) images of the interface were obtained with a JEOL 4000EX electron microscope. The whisker geometry used for HREM imaging is described in Reference 2. High spatial resolution (< 2-nm-diameter probe) parallel-collection electron energy loss spectroscopy (PEELS) measurements were obtained with a Philips EM400T/FEG microscope equipped with a Gatan Model 666 spectrometer.

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TEM of grain growth and phase transformations during creep of SCS-6 silicon carbide fibers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100138129 ◽

1995 ◽

Vol 53 ◽

pp. 350-351

Author(s):

L. A. Giannuzzi ◽

C. A. Lewinsohn ◽

C. E. Bakis ◽

R. E. Tressler

Keyword(s):

Silicon Carbide ◽

Creep Rate ◽

Vapor Deposition ◽

Chemical Vapor ◽

Primary Creep ◽

Excess Carbon ◽

Silicon Carbide Fibers ◽

Sic Fiber ◽

Carbon Core ◽

Grain Width

The SCS-6 SiC fiber is a 142 μm diameter fiber consisting of four distinct regions of βSiC. These SiC regions vary in excess carbon content ranging from 10 a/o down to 5 a/o in the SiC1 through SiC3 region. The SiC4 region is stoichiometric. The SiC sub-grains in all regions grow radially outward from the carbon core of the fiber during the chemical vapor deposition processing of these fibers. In general, the sub-grain width changes from 50nm to 250nm while maintaining an aspect ratio of ~10:1 from the SiC1 through the SiC4 regions. In addition, the SiC shows a <110> texture, i.e., the {111} planes lie ±15° along the fiber axes. Previous has shown that the SCS-6 fiber (as well as the SCS-9 and the developmental SCS-50 μm fiber) undergoes primary creep (i.e., the creep rate constantly decreases as a function of time) throughout the lifetime of the creep test.

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Seeking to uncover biology's chemical roots

Emerging Topics in Life Sciences ◽

10.1042/etls20190012 ◽

2019 ◽

Vol 3 (5) ◽

pp. 435-443 ◽

Cited By ~ 3

Author(s):

Addy Pross

Keyword(s):

Environmental Changes ◽

Biological Systems ◽

Significant Development ◽

The Road ◽

Physical Chemical ◽

Systems Chemistry ◽

Biological World ◽

Inanimate Matter ◽

The Origin Of Life ◽

Opening Up

Despite the considerable advances in molecular biology over the past several decades, the nature of the physical–chemical process by which inanimate matter become transformed into simplest life remains elusive. In this review, we describe recent advances in a relatively new area of chemistry, systems chemistry, which attempts to uncover the physical–chemical principles underlying that remarkable transformation. A significant development has been the discovery that within the space of chemical potentiality there exists a largely unexplored kinetic domain which could be termed dynamic kinetic chemistry. Our analysis suggests that all biological systems and associated sub-systems belong to this distinct domain, thereby facilitating the placement of biological systems within a coherent physical/chemical framework. That discovery offers new insights into the origin of life process, as well as opening the door toward the preparation of active materials able to self-heal, adapt to environmental changes, even communicate, mimicking what transpires routinely in the biological world. The road to simplest proto-life appears to be opening up.

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