ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
C-B-Si coatings were formed on a Si3N4 fiber using chemical vapor deposition and embedded in a Si-N-C matrix using polymer impregnation and pyrolysis. The boron-containing layer was anticipated to form borosilicate glass and seal oxygen-diffusion passes. Two types of C-B-Si coatings were tested on the fiber–matrix interface, and they improved the oxidation resistance of the composite. The first coating was multilayered: a crystalline sublayer composed of B-Si-C was sandwiched between two graphitelike carbon sublayers. The second coating was a graphitelike carbon layer containing a small amount of boron and silicon. The carbon (sub)layer of both coatings weakened the fiber–matrix bonding, giving the composites a high flexural strength (1.1 GPa). The composites retained 60%–70% of their initial strength, even after oxidation at 1523 K for 100 h. The mechanism for improved oxidation resistance was discussed through the microstructure of the interface, morphology of the fracture surface, and oxygen distribution on a cross section of the oxidized composite.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1151-2916.2002.tb00358.x
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