An Assessment of Variability in the Average Tensile Properties of a Melt-Infiltrated SiC/SiC Composite

Abstract

Woven, SiC/SiC Ceramic Matrix Composites (CMCs), manufactured by the slurry-cast, melt-infiltration process are under consideration as combustor liner materials in aircraft gas turbine engines. Tensile properties (elastic modulus, proportional limit strength, in-plane tensile strength, and strain to failure) of the CMC, manufactured during two separate time periods (9/99 and 1/01), were determined at 816 and 1204°C by conducting tensile tests on specimens machined from the CMC plates. A total of 24 tensile tests were conducted for each temperature and CMC variant combination. In this study, average tensile properties of the two CMC variants were statistically compared to evaluate significant differences, if any, within the CMC's properties. A random sampling method was also used to assess the variability exhibited by the mean values of the four tensile properties. By varying the group size of the random sample, the minimum number of tensile tests required to characterize the mean value of each tensile property for the CMC was determined.