Hh. Shin et al., FABRICATION, MICROSTRUCTURE, AND MECHANICAL-PROPERTIES OF TAC PARTICULATE AND SIC FIBER-REINFORCED LITHIA-ALUMINA-SILICA COMPOSITES, Journal of materials research, 10(3), 1995, pp. 602-608
Additions of 0 to 9 mol% Ta2O5 to a lithia-alumina-silica glass-cerami
c matrix Nicalon SiC-reinforced composite increased the elastic modulu
s and ultimate strength of the composite. The additive fostered sphere
ulitic growth of beta-eucriptite solid solution crystals which concent
rated Ta2O5 at sphereulite boundaries and adjacent to the fiber-matrix
carbon-rich interphases. These regions reacted with the interphases a
s well as soluble carbon monoxide gas to convert them to TaC. The form
er reaction was shown to be thermodynamically favorable above 983 degr
ees C, while the latter was favorable above 1249 degrees C. The improv
ement in mechanical properties was attributed to TaC particulate reinf
orcement, and suggests a simple glass-ceramic route to the fabrication
of particulate-reinforced ceramic matrix composites.