Ceramic composites reinforced with modified silicon carbide whiskers and method for modifying the whiskers

Patent · Tue Jan 01 00:00:00 EST 1991

OSTI ID:867711

Tiegs, Terry N ^[1]; Lindemer, Terrence B ^[2]

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1. Lenoir City, TN
2. Oak Ridge, TN

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.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• DOE Contract Number: AC05-84OR21400
• Assignee: Martin Marietta Energy Systems, Inc. (Oak Ridge, TN)
• Patent Number(s): US 4994416
• OSTI ID: 867711
• Country of Publication: United States
• Language: English

Related Subjects

ceramic
composites
reinforced
modified
silicon
carbide
whiskers
method
modifying
whisker-reinforced
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
composites reinforced
composite mat
crack propagating
inhibit chemical
ceramic mater
surface oxide
/501/264/427/