Effects of in situ fiber strength characteristics on mechanical properties of SiC(f)/SiC composites

摘要

Nicalon-fiber-reinforced silicon carbide (SiC) matrix composites were tested in flexure at room and elevated temperatures. The measured strength of composites decreased slightly from a room temperature value of 400 MPa to 380 MPa at 1200 C. However, at 1300 C strength decreased significantly to 290 Mpa. The rapid decrease in strength over 1300 C is believed to be due to degradation in strength of the reinforcing fibers. In situ fiber strength and fiber pullout distribution in fractured composites were estimated by fractographic techniques. Correlations were made between the measured strengths of composites to the in situ fiber strength characteristics to explain the mechanical properties of composites at room and elevated temperatures.