Improving fracture toughness in slip-cast alumina [abstract]

Abstract

Engineering ceramics, such as alumina, exhibit a number of desirable qualities including high strength and stiffness, resistance to chemical attack, high hardness or wear-resistance, good thermal conductivity and utility in high temperature situations. These properties make alumina a very desirable material choice for utilization in engines, turbines and a multitude of other high temperature applications or environments. However; engineering ceramics are also brittle, cracking easily. This tendency of alumina to crack can lead to catastrophic equipment failure, greatly limiting its application. This research project is focusing on improving the fracture toughness of slip-cast alumina by reinforcing the ceramic with multi-walled nanotubes (MWNT) and silicon carbide (SiC) nanofibers. Alumina samples reinforced with varying volume percentages of MWNT's and SiC nanofibers are compared against control sets of non-reinforced alumina parts. All alumina slips are deagglomerated via an ultrasonic horn and are then cast in plaster molds. The alumina samples are dried, fired, and machined into ASTM B modulus of rupture bars. The fracture toughness is measured using the single edge v-notched beam method. It is the hope of the group that this new and explorative research will result in a formulation of nanoscale reinforcement that significantly improves fracture toughness in alumina.