In this work nickel coated iron oxide (Fe2O3) pellets of different particle sizes ranging between 500~900 μm were prepared using chemical reduction method. Hypophosphite bath in alkaline tartarate was used as a chemical coating bath for Fe2O3 particles with Ni, then sintered at 1000°C in a reducing atmosphere for 60 min to produce metallic filters having a composition of Fe70 wt.%-Ni 30 wt.% in the shape of cylindrical candles.
Extensive metallographic studies using optical and scanning electron microscopy were carried out. It was found that the coating layer of the nickel on the iron oxide powder is about 250 mm thick. Sintering of the coated powder takes place by neck growth formation between the coated pellets. The magnetic properties of the iron oxide pellets, the Ni coated ones and the related sintered Fe-Ni filters were measured by a vibrating sample magnetometer (VSM).The results indicate that the reduced Fe2O3 to Fe has a saturation induction (Bs) value of 1.47 (electromagnetic unit/gram) emu/g which form a solid solution Fe-Ni with the Ni layer having a Bs value 129.6 emu/g and coercive force (Hc) value of 16.5 (Orested) Oe. The porosity values, as determined by the Poresizer apparatus, were between 27.5% and 41.5% corresponding to 5.5 g/cm3 and 3.1 g/cm3 density respectively.
Keywords: porous materials, filters,