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301-55 What are the factors that affect the apparent density and tap density of reduced iron powder?

301-55 What are the factors that affect the apparent density and tap density of reduced iron powder?

1. Apparent density
   Apparent density refers to the mass of free loose powder in unit volume when reducing iron powder is filled naturally in container, expressed in g/cm3. The main reasons that affect the apparent density of iron powder are as follows:1.1 Powder size: the smaller the particle size is, the smaller the apparent density is.1.2 Particle shape: the more complicated the shape is, the smaller the apparent density is.1.3 Surface roughness

   1.4 Particle size distribution: when the proportion of fine powder in iron powder increases, the loose density decreases, and the apparent density increases with the addition of proper amount of fine powder in coarse iron powder.

2. Tap density
Tap density is a kind of powder density measured by vibration and tapping under specified conditions when the iron powder is filled in vibrating container. Vibration makes the iron particles pile and compact, but there are still a lot of pores in the powder. The ratio of apparent volume between the pore volume and powder is called porosity.
2.1 The relation between the tap density and the porosity in the powder: The porosity in the reduced iron powder includes the void between particles and the smaller pore inside the particles.

2.2 If the particle sizes are different, the smaller particles are filled into the gap of the larger particles, and the porosity will be reduced, and the shape of the particle will affect the porosity, and the more complex the shape is, the larger the porosity is.