Figure 4

Slope surface roughness. (a,b) Representative x-ray images showing slope surface fluctuation of powders with an average diameter of 67 µm (a) and 23 µm (b). (c,d) Representative slope surface profile of powders with average diameters of 67 µm (c) and 23 µm (d). Height and X-position are measured with respect to the y-x coordinate shown in (a,b). (e,f) Arithmetic average slope surface roughness (Ra) versus time of powders with average diameters of 67 µm (e) and 23 µm (f). A total of 35 “Ra” measurements were obtained for each powder. A time lapse of 1.5 ms was used between each measurement. The powder with an average diameter of 67 µm showed an average “Ra” of 38 µm with a standard deviation of 11 µm. The powder with an average diameter of 23 µm showed an average “Ra” of 20 µm with a standard deviation of 6 µm.