Robocasting of silicon nitride with controllable shape and architecture for biomedical applications

Abstract

Silicon nitride (Si 3 N 4 ) implants are used in spinal fusion surgery and are under development for use in other biomedical applications. The ability to create Si 3 N 4 implants with anatomically relevant shapes and controllable architecture can be beneficial in these applications. In the present study, an aqueous paste composed of Si 3 N 4 powder and sintering additives was prepared with the requisite rheology and formed into structures with different geometry and architecture using a robocasting technique.Sintering and hot isostatic pressing produced an almost fully dense Si 3 N 4 phase (density=3.23AE0.01 g/cm 3 ) with a fibrous microstructure. Four-point bending tests of as-fabricated dense beams showed a flexural strength of 552AE68 MPa. Together, these results indicate that robocasting combined with sintering and hot isostatic pressing can provide a viable manufacturing approach to create Si 3 N 4 implants with controllable shape and architecture for applications in orthopedic and dental surgery. K E Y W O R D Sadditive manufacturing, flexural strength, rheology, robocasting, silicon nitride

Additive manufacturing and characterization of complex Al2O3 parts based on a novel stereolithography method

“…The distribution of particles was homogeneous in which no apparent clustering or big voids were observed on the fracture surface of the green body before thermal debinding (Figure A). After the bodies were successfully thermal debound, the Al 2 O 3 particles were randomly packed with fine pores (Figure B), which was beneficial to achieve the sintered part with higher density . Furthermore, although the combination between each layer was relatively weak after debinding, no cracks and delaminations existed on the surface and fractured cross‐section (Figure C).…”

“…After the bodies were successfully thermal debound, the Al 2 O 3 particles were randomly packed with fine pores ( Figure 4B), which was beneficial to achieve the sintered part with higher density. 21 Furthermore, although the combination between each layer was relatively weak after debinding, no cracks and delaminations existed on the surface and fractured cross-section ( Figure 4C). These features indicate that the Al 2 O 3 green parts were prepared by SLA technique with good forming quality and the heating schedule for the green body was suitable.…”

Ceramic Robocasting: Recent Achievements, Potential, and Future Developments

“…Up to date, a wide range of single‐ceramic structures with feature size down to 60–100 µm and density above 90% T.D. are commonly reported . Recent trends on ceramic robocasting research activities include single and multi‐material printing, combinatorial processes such as UV‐curing and gel‐casting‐assisted ceramic robocasting, as well as the shapeable ceramic structures by robocasting .…”

“…Copyright 2012, The American Ceramic Society. d) Reproduced with permission . Copyright 2017, The American Ceramic Society.…”

“…In general, advanced ceramic materials are categorized into (i) technical and (ii) functional ceramics. Several examples of technical ceramic materials include oxide‐based materials such as silica (SiO 2 ), alumina (Al 2 O 3 ), stabilized zirconia (ZrO 2 ), toughened Al 2 O 3 or ZrO 2 , hydroxyapatite (HA), tricalcium phosphate (TCP), and nonoxide‐based materials such as silicon carbide (SiC), silicon nitride (Si 3 N 4 ), aluminum nitride (AlN) and boron carbide (B 4 C) . Functional ceramics, on the other hand, cover a broader range of materials that include ferroelectric titanate‐based materials (e.g., BaTiO 3 and PbTiO 3 ), magnetic ferrite‐based materials (e.g., NiFe 2 O 4 and BaFe 12 O 19 ), superconductor materials (YBa 2 Cu 3 O 7 ), and other electroceramic materials .…”