The effect of inhibitors on material and mechanical properties of oxidized carbon-carbon composites

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references.Issued also on microfiche from Lange Micrographics.The carbon-carbon laminates examined in this research program are two-dimensional, eight harness satin weaves with boron carbide (B4C) inhibitor particles and a multi-layer silicon carbide (SiC) coating. These inhibitor particles included in the oxidation protection system (OPS) react with oxygen that penetrates through the cracks of the external barrier coatings to form a glass phase, and act as an internal sealant to provide extended oxidation protection. Oxidation testing of the carbon-carbon specimens is performed as a function of time and temperature in order to isolate the contribution of the inhibitor. Oxidation at constant temperature examines the importance of temperature on the length of exposure. The "temperature cycling" oxidation approach examines the importance of fatigue crack formation due to expansion and contraction. Mass loss and material property degradation is assessed with subsequent exploratory nondestructive testing of rheometry and piezoelectric ultrasonic composite oscillator techniques (PUCOT). An analytical diffusion model is developed to predict composite degradation for given exposure conditions, and these results are compared with the experimental data generated. Oxidation specimens are trimmed from a single C-C panel resulting in coupons having dimensions of approximately 4 mm thick, 11.5 mm wide, and 37 mm long, with coating on the front and back sides only