Influence of fiber coatings on the oxidation of fiber-reinforced SiC composites

Conference · Fri Jan 01 04:00:00 EST 1993

OSTI ID:6771913

Tortorelli, P F; Riester, L; Lowden, R A ^[1]; Nijhawan, S ^[2]

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1. Oak Ridge National Lab., TN (United States)
2. Coe Coll., Cedar Rapids, IA (United States)

Thermogravimetric analysis was used to study the reaction kinetics associated with high-temperature air oxidation of graphite- or BN-coated Nicalon-reinforced SiC composites. For those with graphite interlayers, the shapes of the thermogravimetric curves, and the dependencies of weight changes on interfacial layer thickness and exposure temperature, could be explained on the basis of concurrent reactions associated with oxidation of the graphite and the formation of SiO[sub 2] on the matrix and fibers. The oxidation resistance of SiC with BN-coated Nicalon fibers was significantly better than when graphite coatings were used. Flexure tests of Nicalon/graphite/SiC previously oxidized in air at 950[degree]C revealed that degradation of fracture resistance can be detected after very short exposure times (less than 1 h). Accordingly, a knowledge of reaction kinetics is important in characterizing environmental effects on fracture and damage and in predicting the rate of properties degradation. 12 refs, 4 figs, 2 tabs.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6771913
• Report Number(s): CONF-930164-4; ON: DE93006742
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360205 -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
360604* -- Materials-- Corrosion
Erosion
& Degradation
BORON COMPOUNDS
BORON NITRIDES
CARBIDES
CARBON
CARBON COMPOUNDS
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
COATINGS
COMPOSITE MATERIALS
ELEMENTAL MINERALS
ELEMENTS
FIBERS
FLEXURAL STRENGTH
GRAPHITE
GRAVIMETRIC ANALYSIS
MATERIALS
MECHANICAL PROPERTIES
MINERALS
NITRIDES
NITROGEN COMPOUNDS
NONMETALS
OXIDATION
PNICTIDES
PROTECTIVE COATINGS
QUANTITATIVE CHEMICAL ANALYSIS
REINFORCED MATERIALS
SILICON CARBIDES
SILICON COMPOUNDS
TEMPERATURE RANGE
TEMPERATURE RANGE 1000-4000 K
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS