Fabrication of Ni-coated Al 2O 3 powders by the heterogeneous precipitation method

Abstract

Ni-coated Al 2O 3 powders were prepared by the heterogeneous precipitation method using Al 2O 3, Ni(NO 3) 2·6H 2O and NH 4HCO 3 as the starting materials. The amorphous NiCO 3·2Ni(OH) 2·2H 2O was uniformly coated on the surface of Al 2O 3 particles with the thickness of 20 nm. The amorphous coating layer was crystallized to NiO with the size of about 15 nm at 500°C for 2 hours in air, meantime, the dispersant was eliminated. NiO was completely reduced to Ni at 700°C for 4 hours in hydrogen atmosphere. Ni with the size of about 20 nm in the coating layer was spherical and weakly agglomerated. The continuous coating layer became discontinuous during heating treatment.