Fracture Behaviour of Pressureless Sintered Nickel-Reinforced Alumina Composites

Nickel-reinforced alumina composites have been manufactured by aqueous slip casting and pressureless sintered under flowing atmosphere of argon with 0,36 and 1% of oxygen in order to force interfacial reactions leading to the formation of a nickel-aluminum spinel. Colloidal stability of concentrated suspensions of alumina with 5, 10 and 15 vol% of nickel has been studied in terms of zeta potential, rheometry and packing density. The processed composites show a high dispersion of the nickel into the alumina matrix and green densities of 60-70 %th. The effect of sintering temperature and atmosphere on the mechanical behaviour of the composites has been investigated through Vickers indentation and fractographic SEM observations.