Some properties of sintered materials

The mechanical properties of die-compacted sintered nickel compacts prepared from closely sized sieve fraction of annealed Sherritt–Gordon wore determined The properties, especially fatigue properties, were found to be dominated by the presence of film like porosity in the grain boundaries. The occurrence of this porosity was at the original particle boundaries and its form was attributed to botryoidal shape of the original powder particles. A mechanism for the propagation of the fatigue crack is suggested. Several iron powders were carefully characterised. Thin steel strip was prepared from these samples using a slurry technique. Binder was used in the slurry to give coherent strip before rolling. The properties of the green strip were found to be affected by the particle size and particle size distribution of the original powder. The presence of binder in the strip contributed towards the green strength especially at high roll loads. strength was observed to develop quickly during sintering, for sintering times of the order of sixty seconds duration although little or no densification occurred. Specimens of near-theoretical density were prepared by re-rolling and re-sintering. Despite the high density of these specimens the mechanical properties were poor.