Detailed Study of the Tensile Behavior of a Two-Dimensionally Woven Nicalon™/Sylramic™ Ceramic Matrix Composite

A round-robin study was conducted on the tensile behavior of a Nicalon™ fiber reinforced Sylramic™ ceramic matrix composite (CMC). The goals of the US federal government-funded study were: 1) to determine the precision and bias of ASTM Test Method for Monotonic Tensile Strength Testing of Continuous Fiber-Reinforced Ceramic Composites with Solid Rectangular Cross-Sections at Ambient Temperatures (C 1275), 2) to establish an expansive data base for a single CMC, and 3) to evaluate a statistically-significant sample size of a single CMC for processing and design purposes. The CMC was comprised of eight plies of ceramic grade Nicalon™ fabric in a symmetric 0/90 lay-up, a proprietary boron nitride-containing interphase, and a silicon nitrocarbide matrix derived from polysilazane. Tabbed in-plane, reduced gage-section tensile test specimens (3 × 12 × 150-mm overall, 3 × 8 × 35-mm gage section) were monotonically tested in displacement control (0.02 mm/s) at room temperature in face-loaded grips. Five industrial, two governmental, and two academic laboratories participated, each testing ten tensile test specimens for a total of ninety tests. Results were analyzed for variations in test procedures between laboratories, material density/porosity/panel of origin, elastic constants, and nondestructive evaluation characteristics. Repeatability and reproducibility were assessed from coefficients of variation that ranged from 4 to 10%.