X-RAY MICROTOMOGRAPHY OF CERAMIC AND METAL-MATRIX COMPOSITES

Capabilities and limitations of X-ray computed microtomography (CT) in characterizing relevant composite material issues as identified durin g manufacturing processes were investigated. Damage in engine subcompo nents was evaluated and compared with damage detected in pedigreed cou pon type specimens. The system used is a newly developed state-of-the- art X-ray computed tomography system capable of providing digital radi ography, computed tomography and computed laminography. CT was found v iable for characterizing processing defects and coating effect in ther mally shocked carbon fiber reinforced silicon carbide matrix (C/SiC) s amples. CT results from mechanically tested silicon carbide fiber rein forced reaction bonded silicon nitride (SiC/RBSN) matrix sample were e valuated and compared to engine tested SiC/RBSN turbine vanes. Thermom echanically cycled SiC (SCS-6) fiber reinforced Timetal 21S samples sh owed viability of CT in detecting composite constituents and limitatio ns of CT in detecting matrix and fiber cracking. Also an engineering a nalysis approach was proposed to continuously integrate nondestructive evaluation modalities in the design-manufacturing-prototyping cycle o f engine components.