Sintering behaviour of NiO-Fe2O3 composites

NiO-Fe2O3 composites are promising electrodes for fused-salt electrolysis. Pure NiO and Fe2O3 green composites were sintered at temperatures up to 1623 K and the physical, electrical, morphological and crystallographical changes were studied. Density and hardness increased with sintering, mechanical strength was improved and porosity decreased. There was a rapid reduction in electrical resistivity with a lowest value of 0.3 ohm.cm at 1623 K. The high-temperature operation aided the conversion of insulating powders into a homogeneous hard, semiconducting spinel NiFe2O4. The crystalline nature of the sintered composites was observed by XRD, the grain size of the NiFe2O4 corresponding to a d-value of 0.2513 nm. 5 refs.