Occurrence forms of major impurity elements in silicon carbide

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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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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LASER INDUCED ORDERING AND DEFECTS IN ION-IMPLANTED HEXAGONAL SILICON CARBIDE

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1980420 ◽

1980 ◽

Vol 41 (C4) ◽

pp. C4-111-C4-112 ◽

Cited By ~ 1

Author(s):

V. V. Makarov ◽

T. Tuomi ◽

K. Naukkarinen ◽

M. Luomajärvi ◽

M. Riihonen

Keyword(s):

Silicon Carbide ◽

Ion Implanted

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Mineral composition and gemological characteristics of the fossil marine reptiles of the Ulyanovsk region

Proceedings of higher educational establishments Geology and Exploration ◽

10.32454/0016-7762-2018-5-12-16 ◽

2018 ◽

pp. 12-16 ◽

Cited By ~ 4

Author(s):

D. A. Petrochenkov

Keyword(s):

Chemical Composition ◽

Bone Tissue ◽

Mineral Composition ◽

Bone Structure ◽

Upper Jurassic ◽

Marine Reptiles ◽

Ulyanovsk Region ◽

Impurity Elements ◽

Wide Assortment

Fossils of marine reptiles are a new jewelry and ornamental material and collected in the Ulyanovsk region from the Upper Jurassic deposits. They consist of (wt. %): calcite — 52, apatite — 24 and pyrite — 23, and also gypsum presents. The contents of radioactive and carcinogenic elements are close to background. The original bone structure of reptiles is preserved. Apatite replaces the bone tissue of marine reptiles, forming a cellular framework. According to the chemical composition, apatite refers to fluorohydroxyapatite with an increased Sr content. The size of the crystals is finely-dispersed. Calcite and pyrite fill the central parts of the cells. Calcite crystals of isometric and elongated shape, 0,01—0,05 mm in size, form blocks up to 0,3 mm during intergrowth. Calcite fills thin, discontinuous veins along the contour of cells with a width of up to 0,03 mm. In calcite, among the impurity elements, there are (wt. %, on the average): Mg — 0,30, Mn — 0,39 and Fe — 0,96. Pyrite forms a dispersed impregnation in calcite and apatite, content of impurities is, wt. %: Ni — up to 0,96 and Cu — up to 0,24. On technological and decorative characteristics of fossils of sea reptiles of Ulyanovsk region are qualitative jewelry and ornamental materials of biomineral group, allowing to make a wide assortment of jewelry and souvenir products.

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