Abstract
Ceramics will be widely used for enhancing the efficiency of power generating systems, particularly gas turbines. However, ceramics used in these systems suffer damage owing to impact by foreign objects. In this study, various ceramic plates are impacted by a spherical projectile with an impact velocity of 320 m/s. The volume of the cone cracks formed on the plates decreases with an increase in the fracture toughness of the ceramic material. No cone cracks are formed on the zirconia (3Y-TZP) plate because crack formation is prevented by stress-induced phase transformation outside the impacted region. The volume of the cone crack is higher and the energy consumed by surface formation is smaller in transgranular-fractured ceramics than in intergranular-fractured ones. The fracture process can be controlled by controlling the characteristics of the grain boundaries, as well as by stress-induced phase transformation.
