Synthesis and characterization of alumina-nickel nanocomposite through sol-gel route by in situ reduction

Brittle matrix is usually toughened by metallic phases to enhance the fracture toughness. In the present study of alumina nickel, composite with 15 wt% of nickel was prepared by sol-gel route by using Al(C3H7O)3, NiCl2.6H2O, and dextrose as precursor. The precursor gel composite was reduced by the novel in situ reduction to obtain metallic nickel dispersed in the alumina matrix. Prior to this reduction of NiCl2.6H2O, a novel technique of repeated evacuation and purging of the gel was carried out with N2 in order to replace the air present in the pores of gel, and secondly the in situ reduction was carried out in a charcoal boat in a N2 atmosphere to generate sufficient reducing atmosphere to prevent reoxidation of metallic Ni. The alumina-nickel nanocomposites were thoroughly investigated by different characterization techniques like X-ray diffraction, Dynamic light scattering, etc. Interestingly, the synthesis of a finer grained alumina-Ni composite was obtained when it was reduced at higher temperature, unlike expected and this phenomenon was explained in the text.