Improvement of flow of an iron-copper-graphite powder mix through additions of nanoparticles

• A method is proposed to eliminate the poor flowability of common PM steel premixes;
• Admixed graphite if first doped with carbon black and silica fume nanoparticles;
• Doped graphite is added to the premix 5 minutes before the blending ends.
• The method has minimal effect on apparent density of such premixes.

Nanoparticles of carbon black, silica and ferrous oxide were added to FC-0208 powder metallurgy blends prepared using ethylene bis stearamide as lubricant to investigate their influence on improving flowability of this formulation that tends to be cohesive. This study consisted in preparing multiple premixes having different quantities of nanoparticles of different types and evaluating their impact on flowability and apparent density according to MPIF standards. The important variables for the distribution of nanoparticles on the surface of the host particles were the sequence of addition of all of the constituents, the quantity of nanoparticles and the mixing time. It was possible to identify a condition presenting good flowability with a flow time of 34.9 s/50 g and an apparent density of 2.78 g/cm3.

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