Effect of a Boron Nitride Interphase That Debonds between the Interphase and the Matrix in SiC/SiC Composites

Typically, the debonding and sliding interface enabling fiber pullout for SiC‐fiber‐reinforced SiC‐matrix composites with BN‐based interphases occurs between the fiber and the interphase. Recently, composites have been fabricated where interface debonding and sliding occur between the BN interphase...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 2004-01, Vol.87 (1), p.104-112
Main Authors: Morscher, Gregory N., Yun, Hee Mann, DiCarlo, James A., Thomas-Ogbuji, Linus
Format: Article
Language:English
Subjects:
Adhesives
Applied sciences
Building materials. Ceramics. Glasses
Ceramic industries
Ceramics
Cermets, ceramic and refractory composites
Chemical industry and chemicals
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Materials science
Matrix
Other materials
Physics
Sintering
Specific materials
Structural ceramics
Technical ceramics
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Summary:Typically, the debonding and sliding interface enabling fiber pullout for SiC‐fiber‐reinforced SiC‐matrix composites with BN‐based interphases occurs between the fiber and the interphase. Recently, composites have been fabricated where interface debonding and sliding occur between the BN interphase and the matrix. This results in two major improvements in mechanical properties. First, significantly higher failure strains were attained due to the lower interfacial shear strength with no loss in ultimate strength properties of the composites. Second, significantly longer stress‐rupture times at higher stresses were observed in air at 815°3C. In addition, no loss in mechanical properties was observed for composites that did not possess a thin carbon layer between the fiber and the interphase when subjected to burner‐rig exposure. Two primary factors were hypothesized for the occurrence of debonding and sliding between the BN interphase and the SiC matrix: a weaker interface at the BN/matrix interface than the fiber/BN interface and a residual tensile/shear stress‐state at the BN/matrix interface of melt‐infiltrated composites. Also, the occurrence of outside debonding was believed to occur during composite fabrication, i.e., on cooldown after molten silicon infiltration.
ISSN:0002-7820
1551-2916
DOI:10.1111/j.1551-2916.2004.00104.x