Postprocessing Study for the Controllable Structures of Ceramic Green Parts Realized by a Flexible Binder Jetting Printing (BJP) Solution

Abstract

For indirect ceramic additive manufacturing (AM), green parts’ initial densities are low, limiting the postprocessing strengthening under atmospheric pressure. This study employed binder jetting printing (BJP) based on the polycondensation curing of urea-formaldehyde resin to produce series of Al2O3 green specimens with controllable structures. Further, an integrated postprocessing procedure, including the sequential stages of presintering, ceramic slurry infiltration, and final sintering, was conducted on these green specimens with designed structural characteristics for verifying strengthening mechanism. Using a self-developed BJP machine system and the related material which are flexible in process, this study printed green specimens with strong bonding (flexural strength above 6.84 MPa), additionally can regulate their initial densities within the wide range between 21.7%∼43.9%. Infiltrated with ceramic slurry, low-density green specimens were significantly strengthened via final sintering, realizing final densities, flexural strength, and compressive strength of 73.2%, 43.15 MPa, and 331.17 MPa, respectively. In comparison, high-density specimens performing poor infiltration obtained limited density increment after final sintering, but better mechanical properties and surface strengthening were realized, exhibiting final densities, flexural strength, comprehensive strength, surface roughness Ra, and Vickers hardness of 70.1%, 63.22 MPa, 450.18 MPa, 9.73 μm, and 4.58 GPa, respectively. In summary, this study is helpful to provide the technical reference for custom AM ceramic green parts and the postprocessing optimization.

Effects of process parameters, debinding and sintering on the microstructure of 316L stainless steel produced by binder jetting

“…It allows, in principle, to produce parts from almost any powdered feedstock material, from metals to ceramics, since there are no restrictions regarding high melting points, reflectivity, etc. [8][9][10][11][12][13][14]. Considering that the printing process is performed at room temperature, no effect about thermal conductivity needs to be considered and concerns like presence of residual stresses, part distortions or crack formation are significantly reduced.…”

Microstructure Evolution and Performance Improvement of Silicon Carbide Ceramics via Impregnation Method

“…At the same time, in order to avoid defects during the debinding process, heat preservation was carried out at 450 °C for 30 min. In order to make sure that the green body has sufficient strength in the subsequent process, the pre-sintering was carried out immediately after the debinding, and the temperature of pre-sintering was 1650 °C [ 20 ]. Finally, the C/SiC preform was prepared, named P0.…”

Tailoring α-alumina powder morphology through spray drying for cold consolidation by binder jetting

“…Among these techniques, the most important are Stereolithography (SLA) [5][6][7], Material Extrusion (e.g. Fused Deposition Modeling) [8][9][10], Robocasting/Direct Ink Writing (DIW) [11][12][13]) and Binder Jetting (BJ) [14][15][16][17].…”