Page 131 - MSAM-2-3

Materials Science in Additive Manufacturing Powder alteration caused by L-PBF process

this axis are comparable to the recoater effect identified in coefficients of variation on the measurements of the three
the first experiment. samples taken in each zone are <0.4%, <0.3%, and <0.6%
on Dv90, Dv50, and Dv10, respectively.
3.2.2. Results of double contamination
As can be observed in this experiment, reducing the
Figure 15 illustrates the four concentric cylinders printed distance between melted parts increases the proportion of
for Experiment 2B to study what happens when parts are coarse particles and significantly reduces the percentage of
printed in close proximity. As shown in Figure 16, the fine particles in the area. Powder located at a distance from
cumulative PSD shifts gradually rightward toward bigger the melt pool remains unaffected, with a PSD quite similar
particles, followed by a significant drop in the proportion to that measured in the dispenser.
of fine particles with the gradual movement from zone 4
to zone 1. This implies that zone 1 includes more coarse This change could be attributed to the fact that
particles and less fine particles than zones 2, 3, or 4. laser melting creates spatters and larger particles. This
condensation occurs due to the vaporization of melted
Figure 17 shows that the PSD moved rightward and particles [5,23] . Furthermore, they may agglomerate into
became narrower from zone 4 to zone 1. Likewise, the bigger particles to create satellites. Soundarapandiyan
percentage of smaller particles was significantly reduced. et al. reported that powder particles located near the melt
[11]
As shown in Figure 18, the particles average diameters zone are not only coarser with a wider PSD than particles
D90, D50, and D10 increase gradually by 8%, 16%, and away from the melt pool, but they also demonstrate
24%, respectively, as we move from zone 4 to zone 1. The

Figure 14. Particle-size distribution vertical line.
Figure 12. Particle-size distribution horizontal line.

Figure 15. Part with four concentric cylinders with increasing distance
Figure 13. D-values horizontal line (X-axis). of spacing.

Volume 2 Issue 3 (2023) 8 https://doi.org/10.36922/msam.1781