Dilatrometric sintering study and characterization of alumina-nickel composites

Abstract

Alumina-nickel composite samples (with 0, 10 and 20 vol.% of Ni) are prepared via slip casting method. Nickel and aluminium oxide powders were used as precursors and diammonium hydrocitrate and citric acid were used as dispersants. The obtained materials were analysed by dilatometry, X-ray diffraction and SEM. The densities were measured by Archimedes method and the hardness and fracture toughness were determined by using Vickers hardness tester. Special attention was paid to the linear shrinkage and the effective coefficient of thermal expansion measurements. The shrinkage curves were obtained by dilatometry test in a heating mode. It was shown that the increased amount of Ni particles in Al2O3-Ni composite structure causes reduction of starting densification temperature, increasing temperature of maximum densification and decreasing total shrinkage of the sample during sintering.