Volume 25, Issue 4 (July 1997)
A Comparison of Calculated Geometric Surface Area and Measured BET Surface Area for a Metal Powder
The specific surface areas of gas atomized (spherical) metal powder fractionated into 6 size fractions below 125 μm were determined by BET measurements and by geometric derivation from particle size distributions. The areas obtained were compared and a linear correlation was found. Even though the total areas measured were relatively low, in the range of 0.3 m2, the BET measurements followed the areas derived from particle size with a proportionality factor around 1.8. It was concluded that BET surface area measurements represent true area closely, when true area is understood as the envelope best fitting the powder particles. The deviation of the BET measurements from the true area is concluded to be less than 20%, with increasing accuracy for increasing specific surface area.