High-performance and high-precision Al2O3 architectures enabled by high-solid-loading, graphene-containing slurries for top-down DLP 3D printing

Delamination mitigation in additively manufactured Al2O3 via enhanced thermal postprocessing

“…6 While DLP offers a relatively high resolution amongst the AM techniques, it is limited by the depth of cure which is governed by UV light penetration through the slurry. 6,9,17,18 When ceramic particles are used as filler, the difference in refractive index (RI) between the ceramic powder and UV-curable resin, and light absorption affect the cure depth with higher RI differences and light absorption resulting in reduced cure depth. 19 Additionally, as the ceramic powder volume loading is increased, the refractive index difference of the slurry consequently increases.…”

“…Increasing the ceramic powder loading also acts to increase UV light scattering, reducing the depth of cure and print resolution. 17,18 Due to this, ceramics with a low RI and light absorption (e.g., oxides) are the most viable options and are the only compositions currently commercially available (e.g. Admatec, Lithoz, Tethon).…”

“…DLP slurries contain between 35 and 65 vol% photosensitive resins, which bind the ceramic powders upon UV curing. 17,[20][21][22] In order to densify the printed part, the resin is thermally or chemically removed first, often leading to gas/bubble formation, interlayer delamination, and cracking during sintering. 7,23,24 Consequently, DLP is limited by part thickness and offers limited solutions for parts with geometric features greater than ∼10 mm in any direction.…”

“…One of the primary advantages of DLP is the ability to print with high accuracy and have features on the order of tens of micrometers 6,14,16 with some resolutions as high as 1.1 μm 6 . While DLP offers a relatively high resolution amongst the AM techniques, it is limited by the depth of cure which is governed by UV light penetration through the slurry 6,9,17,18 . When ceramic particles are used as filler, the difference in refractive index (RI) between the ceramic powder and UV‐curable resin, and light absorption affect the cure depth with higher RI differences and light absorption resulting in reduced cure depth 19 .…”

“…Additionally, as the ceramic powder volume loading is increased, the refractive index difference of the slurry consequently increases. Increasing the ceramic powder loading also acts to increase UV light scattering, reducing the depth of cure and print resolution 17,18 . Due to this, ceramics with a low RI and light absorption (e.g., oxides) are the most viable options and are the only compositions currently commercially available (e.g.…”