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Effects of Interface Coating and Nitride Enhancing Additive on Properties of Hi-Nicalon SiC Fiber Reinforced Reaction-Bonded Silicon Nitride CompositesStrong and tough Hi-Nicalon SiC fiber reinforced reaction-bonded silicon nitride matrix composites (SiC/ RBSN) have been fabricated by the fiber lay-up approach. Commercially available uncoated and PBN, PBN/Si-rich PBN, and BN/SiC coated SiC Hi-Nicalon fiber tows were used as reinforcement. The composites contained approximately 24 vol % of aligned 14 micron diameter SiC fibers in a porous RBSN matrix. Both one- and two-dimensional composites were characterized. The effects of interface coating composition, and the nitridation enhancing additive, NiO, on the room temperature physical, tensile, and interfacial shear strength properties of SiC/RBSN matrix composites were evaluated. Results indicate that for all three coated fibers, the thickness of the coatings decreased from the outer periphery to the interior of the tows, and that from 10 to 30 percent of the fibers were not covered with the interface coating. In the uncoated regions, chemical reaction between the NiO additive and the SiC fiber occurs causing degradation of tensile properties of the composites. Among the three interface coating combinations investigated, the BN/SiC coated Hi-Nicalon SiC fiber reinforced RBSN matrix composite showed the least amount of uncoated regions and reasonably uniform interface coating thickness. The matrix cracking stress in SiC/RBSN composites was predicted using a fracture mechanics based crack bridging model.
Document ID
Document Type
Technical Memorandum (TM)
Bhatt, Ramakrishana T.
(Army Research Lab. Cleveland, OH United States)
Hull, David R.
(NASA Glenn Research Center Cleveland, OH United States)
Eldridge, Jeffrey I.
(NASA Glenn Research Center Cleveland, OH United States)
Babuder, Raymond
(Case Western Reserve Univ. Cleveland, OH United States)
Date Acquired
September 7, 2013
Publication Date
September 1, 2000
Subject Category
Composite Materials
Report/Patent Number
NAS 1.15:210211
Funding Number(s)
PROJECT: RTOP 523-31-13
Distribution Limits
Work of the US Gov. Public Use Permitted.
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