Abstract
Nano metallic particle-dispersed ceramic hybrids are promising candidates as ceramic-based composites with high mechanical strength and high fracture toughness at room temperature and high temperatures. Some of the metal/ceramic hybrids have a self-healing function against mechanical degradation by surface crack. In the present report, Ni nano-particle dispersed Al_2O_3 hybrids are discussed as high-temperature self-crack healing materials. At elevated temperatures in oxidizing condition such as 1200℃ in air, Ni nano-particles dispersed in Al_2O_3 matrix are oxidized into NiAl_2O_4 with Al_2O_3 matrix and oxide ions diffusing from the surface. On the other hand, outward diffusion of cations takes place simultaneously and causes the formation of NiAl_2O_4 on the surface of the hybrids. Surface cracks introduced to the hybrids are also filled with NiAl_2O_4, as a result, their mechanical recovery is achieved.
