Effect of abrasive grain position patterns on the deformation of 6H-silicon carbide subjected to nano-grinding

Fracture onset coefficients and edge shape transition probabilities made it possible to evaluate the edge fracture characteristics of abrasive grain rationally. By grinding tests of single grain, these probabilities were determined for five materials: regular aluminum oxide, white aluminum oxide, single crystal aluminum oxide, green silicon carbide and black silicon carbide. Using these probabilities, transitions of edge shape distributions were calculated by applying the theory of Markov process to clarify the difference of abrasive materials in edge fracture. As a result, these probabilities proved to be an appropriate index for edge fracture characteristics of grinding grain materials.

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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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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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