Ultrasonic evaluation of thermally shocked Cr/sub 3/C/sub 2//Al/sub 2/O/sub 3/

Chromium carbide (Cr/sub 3/C/sub 2/) has been proved to be a potential material for toughening alumina in biomedical and industrial applications because of its high Young's modulus and erosion resistance. On the other hand, TiC/Al/sub 2/O/sub 3/ composite has been used a magnetic head slider due to its good wear resistance and mechanical strength. In this study we prepare samples of Cr/sub 3/C/sub 2//Al/sub 2/O/sub 3/ composite by injection moulding method. To use this ceramic material as structural components when the temperature varies rapidly, it is necessary to be able to estimate damage or thermal shock cracking. Ultrasonic attenuation measurements are made for assessment of thermal shock damage. Results show that the attenuation increases as the shock temperature raises. Corresponding SEM pictures show although the size of micro-crack doesn't change the depth of the micro-cracks increases. It is demonstrated that ultrasonic attenuation proves to be a reliable tool for evaluating micro-fractures in solids.