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Influence of interfacial shear strength on the mechanical properties of SiC fiber reinforced reaction-bonded silicon nitride matrix compositesThe influence of fiber/matrix interface microstructure and interfacial shear strength on the mechanical properties of a fiber-reinforced ceramic composite was evaluated. The composite consisted of approximately 30 vol percent uniaxially aligned 142 microns diameter SiC fibers (Textron SCS-6) in a reaction-bonded Si3N4 matrix (SiC/RBSN). The interface microstructure was varied by controlling the composite fabrication conditions and by heat treating the composite in an oxidizing environment. Interfacial shear strength was determined by the matrix crack spacing method. The results of microstructural examination indicate that the carbon-rich coating provided with the as-produced SiC fibers was stable in composites fabricated at 1200 C in a nitrogen or in a nitrogen plus 4 percent hydrogen mixture for 40 hr. However this coating degraded in composites fabricated at 1350 C in N2 + 4 percent H2 for 40 and 72 hr and also in composites heat treated in an oxidizing environment at 600 C for 100 hr after fabrication at 1200 C in a nitrogen. It was determined that degradation occurred by carbon removal which in turn had a strong influence on interfacial shear strength and other mechanical properties. Specifically, as the carbon coating was removed, the composite interfacial shear strength, primary elastic modulus, first matrix cracking stress, and ultimate tensile strength decreased, but the first matrix cracking strain remained nearly the same.
Document ID
19900015066
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Bhatt, Ramakrishna T. (Army Aviation Systems Command Cleveland, OH., United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1990
Subject Category
Composite Materials
Report/Patent Number
NAS 1.15:102462
NASA-TM-102462
AVSCOM-TR-90-C-003
E-5250
AD-A224968
Meeting Information
Meeting: Advanced Metal and Ceramic Material Composites Symposium
Location: Anaheim, CA
Country: United States
Start Date: February 23, 1990
End Date: February 27, 1990
Sponsors: Metallurgical Society
Accession Number
90N24382
Funding Number(s)
PROJECT: RTOP 510-01-0A
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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