High Temperature Compression Testing of an Advanced Carbon-Carbon Composite in an Oxidizing Atmosphere

Compression testing of an advanced, three-dimensional weave, carbon-carbon composite was performed from room temperature to 2192°F (1200°C) in an oxidizing environment. The material tested is primarily used for missile nose cones and rocket nozzles. A test system and test method was developed for performing high temperature compression testing and techniques were developed for machining the material to minimize fiber damage and maintain accurate tolerances. Test specimens were cut from a block of the test material in the three principal fiber orientations, and off-axis tests were cut at 45 orientations to each principal fiber direction. The specimens were tested by direct end loading using custom made, ceramic test fixtures, permitting the determination of the compressive modulus and ultimate compressive strength for each principal fiber direction and an approximation of the ultimate shear strength based on the off-axis tests. To document the materials oxidation rate an oxidation study was also performed at temperatures in excess of 11 12°F (600°C). The results demonstrate that the structural integrity of the material was maintained from room temperature to 1472°F (800°C), while moderate oxidation was observed from room temperature to 1472°F (800°C) and severe oxidation occurred above 1472°F (800°C). Based on the data from the oxidation~results, the compression test data generated for the 1472°F (800°C) tests was corrected to account for material loss during each test due to oxidation. The compression test results also demonstrated material symmetry along two of the principal fiber orientations