CRACK-HEALING EFFECT OF AL
2O
3HYBRID MATERIALS
DISPERSED WITH NI NANOPARTICLES VIA THERMAL OXIDATION
D. Maruoka1 and M. Nanko2
1
Graduate School of Engineering, Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka, Niigata, 940-2188, Japan - e-mail: daisuke@stn.nagaokaut.ac.jp
2
Department of Mechanical Engineering, Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka, Niigata, 940-2188, Japan - e-mail: nanko@mech.nagaokaut.ac.jp
Keywords: nanocomposite, Al2O3, High-temperature oxidation, bending strength,
Diffusion
ABSTRACT
Al2O3 hybrid materials dispersed with Ni nano-particles (Ni/Al2O3) have received
great attentions for their excellent mechanical strength and fracture toughness. However, these hybrid materials still have poor fracture toughness in comparison with metallic materials. In the ceramic-based materials, even a small surface crack causes catastrophic failure by a low impact load.
Ni/Al2O3 have crack-healing function via thermal oxidation as well as SiC-dispersed
oxide composites. Recovery of mechanical strength in Ni/Al2O3 was caused by filling
cracks with the oxidation product, NiAl2O4.
NiAl2O4 filled in the cracks is developed by the direct oxidation of surface nano-Ni
particles and diffusion of Ni ions reacted with surface Al2O3. In order to understand
the filling of surface cracks on these hybrid materials, the role of outward diffusion of Ni ions should be investigated.
In the present study, recovery mechanism of mechanical strength was investigated on Ni/Al2O3 in the point of view on high-temperature oxidation kinetics, in particular,
on cation diffusion in the polycrystalline Al2O3 matrix.
