Influence of Si-Doping of Nano-Ni Dispersed Al2O3 Composites on High-Temperature Oxidation

The oxidation kinetics of 5 vol% nano-Ni dispersed Al2O3 with Si-doping (nano-Ni/Al2O3-Si) was studied in the present paper. The starting powder mixture was prepared by drying aqueous slurry consisting of alumina with nickel nitrate and Si (OCH3)4. The powder mixture was reduced at 600 C for 12 h in a stream of Ar-1%H2 gas mixture. Nano-Ni/Al2O3-Si was densified by pulsed electric current sintering. The oxidation test was conducted at 1200–1350 C for 1–14 d in air. Oxidized zone consisted of Al2O3 matrix and NiAl2O4 as the oxidation product. Growth of the oxidized zone followed a parabolic manner. A thin NiAl2O4 layer was also observed on the sample surface. Si-doping decreases growth rate of oxidized zone effectively at lower temperatures such 1200 C. [doi:10.2320/matertrans.MAW201027]