Quantitative characterization of defects in stereolithographic additive manufactured ceramic using X-ray computed tomography

Study of alumina ceramic parts fabricated via DLP stereolithography using powders with different sizes and morphologies

“…However, low relative densities were observed for the sintered alumina parts fabricated using the 55 vol% AA07 or AA1.5 UV‐curable alumina suspensions. This may be attributed to the more difficult densification process for the alumina powders with larger particle sizes, and the pores between the sintered particles cannot be healed after sintering due to the poorer sintering activity of these alumina powders with larger particle sizes 40,43 . Additionally, the sintered alumina parts fabricated using the suspensions prepared from the AA04 alumina powders with near‐spherical morphology exhibited a higher relative density compared to the suspensions prepared using the AKP20 alumina powders with irregular morphology.…”

“…In terms of dimensional contraction, all sintered alumina specimens exhibit the greatest shrinkage in the height direction as a result of their layer-by-layer forming characteristics, and the numerous interlayer gaps in the height direction have been eliminated after sintering process. 31,43 As evident, the lowest relative density and contraction behavior was observed for the sintered alumina objects fabricated from the AA1.5 suspensions containing the alumina powders with the largest particle size. Conversely, the sintered alumina parts fabricated using the AA04 UV-curable alumina suspensions exhibited the highest relative density and shrinkage.…”

“…This may be attributed to the AA04 alumina powders' superior sintering activity and increased curing depth. 43 After enhancing the solid loading of suspensions from 55 to 60 vol%, the relative density of alumina ceramic parts fabricated using the AA07 or AA1.5 alumina powders was observed to significantly increase, which was due to the improved green-body density of printed parts. However, the relative density was not observed to increase when the solid loading increased from 55 to 57.5 vol% for the suspensions prepared using the AA04 or AKP20 alumina powders.…”

“…This may be attributed to the more difficult densification process for the alumina powders with larger particle sizes, and the pores between the sintered particles cannot be healed after sintering due to the poorer sintering activity of these alumina powders with larger particle sizes. 40,43 Additionally, the sintered alumina parts fabricated using the suspensions prepared from the AA04 alumina powders with near-spherical morphology exhibited a higher relative density compared to…”

“…Furthermore, the sintering activity of the AKP20 alumina powders was relatively weaker, when compared to the AA04 alumina powders. 43 All of these characteristics contribute to the sintered AKP20 alumina parts' lower mechanical properties. The mechanical properties of the DAR alumina powders with their nearspherical morphology and smallest particle size of .2 m are slightly inferior to those of the sintered AA04 alumina parts, which may be due to the suspensions having a higher viscosity and resulting green-body with more inhomogeneous particle distribution.…”