High-Temperature Oxidation Behavior of Ni/Al₂O₃ Composites with Various Ni Content

Abstract

Al₂O₃ composites dispersed with 1, 5, 10, and 15 vol% nickel particles were prepared using a pulsed electric current sintering technique. High-temperature oxidation was conducted at temperatures ranging from 1200°C to 1350°C for 6–24 h in air. After oxidation, the sample surface mainly consisted of NiAl₂O₄ oxide. The growth of the oxidized zone in all sample groups followed a parabolic pattern. The influence of the Ni content on the high-temperature oxidation behavior of Ni/Al₂O₃ is discussed. A kinetic model was proposed to explain the growth of the oxidized zone. The diffusion coefficient of oxygen ions through the grain boundaries of the Al₂O₃ matrix can be obtained using the proposed model, which is in agreement with those in the literature.

Fig. 7 Fracture surface of Ni/Al₂O₃ after oxidation at 1300°C for 12 h with their microstructure at IOZ and non-oxidized zone respectively, (a)–(c) for 1 vol% Ni/Al₂O₃, (d)–(f) for 5 vol% Ni/Al₂O₃, (g)–(i) for 10 vol% Ni/Al₂O₃, and (j)–(l) for 15 vol% Ni/Al₂O₃.