Properties and sintering behaviour of fine spherical iron powders produced by a new hydrogen reduction process

For many applications like for diamond tools, magnetorheological fluids, materials absorbing microwaves but mostly for metal injection molding (MIM) fine spherical iron powders are used. The high costs of powder based on the carbonyl or atomizing production route are for many applications a limiting fact. An alternative two-step hydrogen reduction process using a granulated hematite powder, which is a recycling product from steel makers, was developed to produce spherical powder < 25 mm. The experimental results have shown that the morphology or properties of the powder respectively depend strongly on the second temperature step of the reduction process. A further important step is the enclosed powder processing by milling and sieving to remove agglomerates. In this paper the powder properties as well as the sintering behavior as a result of different heat treatment and processing parameters will be discussed.