Synthesis of nickel aluminate nanoceramic compound from aluminum and nickel carbonate by mechanical alloying with subsequent annealing

The aim of present work was to produce pure nickel aluminate (NiAl2O4) nanoceramic compound by high energy milling of nickel carbonate (NiCO3) and aluminum (Al) powders followed by annealing. Phase composition, thermal behavior, morphology and microstructure of powder samples were characterized by means of X-ray diffraction, differential scanning calorimeter, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The results showed that formation of NiAl2O4 spinel compound from NiCO3 and Al powders took place in three steps: oxidation of Al to Al2O3, decomposition of NiCO3 to NiO and CO2, and finally the solid state reaction between Al2O3 and NiO. It was also demonstrated that single phase NiAl2O4 spinel compound can be produced by 5 h of mechanical milling with subsequent annealing of NiCO3/Al mixture at 900 °C for 2 h, which is ∼500 °C lower than the temperatures used in the traditional solid state methods. The particle diameter of the produced NiAl2O4 spinel compound was found to be less than 100 nm as measured by transmission electron microscopy.