Crack Healing of Nano-Ni/Al2O3 Hybrid Materials via High-Temperature Oxidation
Crack-healing effectiveness was investigated on 5 vol% nano-Ni dispersed Al2O3 hybrid materials. Influence of the Y or Si doping or SiC co-dispersion was also studied on the crack healing behavior. Cracks were introduced by a Vickers indentation to be a crack length of approximately 60 μm. Cracks of nano-Ni/Al2O3 were completely disappeared, for example, by oxidation at 1200°C for 6 h in air, Y/Si doped one and SiC co-dispersed one have similar performance of crack disappearance. Bending strength of crack-disappeared samples showed about 550 MPa and was comparable or improved with that of as-sintered one. Mechanism of crack healing was considered as filling up of cracks by NiAl2O4 oxidation product which is developed by outward diffusion of cations at grain boundary of Al2O3 matrix. Nano-Ni/Al2O3 with Y or Si doping or SiC co-dispersion are realized to have crack-healing effectiveness with improved high-temperature oxidation resistance.
Toshio Maruyama, Masayuki Yoshiba, Kazuya Kurokawa, Yuuzou Kawahara and Nobuo Otsuka
D. Maruoka and M. Nanko, "Crack Healing of Nano-Ni/Al2O3 Hybrid Materials via High-Temperature Oxidation", Materials Science Forum, Vol. 696, pp. 378-383, 2011