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Title: Modified silicon carbide whiskers

Abstract

Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

Inventors:
 [1];  [2]
  1. (Lenoir City, TN)
  2. (Oak Ridge, TN)
Publication Date:
Research Org.:
LOCKHEED MARTIN ENRGY SYST INC
OSTI Identifier:
867828
Patent Number(s):
US 5017528
Assignee:
Martin Marietta Energy Systems, Inc. (Oak Ridge, TN) ORNL
DOE Contract Number:  
AC05-84OR21400
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
modified; silicon; carbide; whiskers; whisker-reinforced; ceramic; composites; fabricated; highly; reproducible; manner; beneficating; surfaces; prior; usage; contain; considerable; concentrations; surface; oxides; impurities; interact; composite; material; form; chemical; bond; significantly; reduced; relatively; weak; formed; whisker; crack; propagating; diverted; deflected; whisker-matrix; interface; due; bonding; deter; propagation; depletion; oxygen-containing; compounds; near; region; effected; heat; treating; suitable; oxygen; sparaging; atmosphere; elevated; temperatures; additionally; sedimentation; technique; utilized; remove; suffer; structural; physical; anomalies; render; undesirable; layer; carbon; provided; inhibit; weak chemical; significantly reduce; chemical bond; containing compound; crack propagation; surface region; near surface; ceramic material; ceramic composites; ceramic composite; elevated temperatures; elevated temperature; silicon carbide; composite material; carbide whiskers; significantly reduced; heat treating; chemical bonding; relatively weak; containing compounds; remove whiskers; modified silicon; sedimentation technique; whiskers interact; whiskers prior; suffer structural; suitable oxygen; whisker surfaces; whisker-matrix interface; sparaging atmosphere; physical anomalies; oxygen sparaging; oxygen-containing compounds; reproducible manner; reinforced ceramic; highly reproducible; contain considerable; whisker-reinforced ceramic; surface oxides; considerable concentrations; interface due; carbide whisker; carbide whisker-reinforced; composite mat; crack propagating; inhibit chemical; ceramic mater; surface oxide; /501/428/

Citation Formats

Tiegs, Terry N., and Lindemer, Terrence B. Modified silicon carbide whiskers. United States: N. p., 1991. Web.
Tiegs, Terry N., & Lindemer, Terrence B. Modified silicon carbide whiskers. United States.
Tiegs, Terry N., and Lindemer, Terrence B. Tue . "Modified silicon carbide whiskers". United States. https://www.osti.gov/servlets/purl/867828.
@article{osti_867828,
title = {Modified silicon carbide whiskers},
author = {Tiegs, Terry N. and Lindemer, Terrence B.},
abstractNote = {Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Jan 01 00:00:00 EST 1991},
month = {Tue Jan 01 00:00:00 EST 1991}
}

Patent:

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