Ceramic-ceramic composites with reaction bonded matrices

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 1989, Vol.107, p.117-125
• Main Author: Haggerty, John S.
• Format: Article
• Language: English
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/0921-5093(89)90380-8

Reaction bonded ceramic matrix composites offer the potential of improved, reliable high temperature properties with near net-shape processing. Reaction bonded CMCs consolidate by filling the void space within the green part with reaction product, rather than shrinking as occurs during conventional sintering, so sintering aids are not required to relieve stresses through particle/reinforcement rearrangements. The absence of sintering aids in the grain boundaries gives superior high temperature and corrosion properties. Even though processing temperatures are lower than those used in conventional sintering processes, times are long and the internal atmosphere is active with respect to the reinforcement phase. It is particularly critical to avoid degrading the loadbearing reinforcements or their protective coatings in the porous, low modulus matrices. Recently developed high strength, oxidation resistant, reaction bonded Si 3N 4 that reacts to completion in unusually short, low temperature nitriding cycles, makes these composites feasible for the first time.