Interfacial Studies of Refractory Glass-Ceramic Matrix/Advanced SiC FiberReinforced Composites

摘要

The main objective of this program is to characterize the chemistry and structureand microstructure of new advanced small diameter SiC type fibers and how these factors influence the nature of the fiber/matrix interface in refractory glass-ceramic matrix composites. It is the nature of this interface that then determines to a great degree the composite thermal, environmental, and mechanical properties. The fibers under investigation included new experimental polymer derived crystalline SiC fibers as well as the new commercially available low oxygen 'Lox M' Tyranno SiC type fibers. It was found that the mechanical properties of Lox M Tyranno fiber/LAS (lithium aluminosilicate) and BMAS (barium-magnesium aluminosilicate) metal matrix composites were much improved over similar composite materials fabricated with older higher oxygen content Tyranno fibers. An approximately 500 A thick carbon rich fiber/matrix interfacial layer was found to form during the composite fabrication, similar to that found to comparable NICALON fiber composites except for the additional formation of titanium rich crystalline particles within or near the carbon rich layer. The thermal properties and mechanical properties of both LAS and BMAS matrix composites were very similar for either Lox M Tyranno or NICALON fiber reinforcement.