Fabrication of dense SiSiC ceramics by a hybrid additive manufacturing process

Abstract

In this work, we report the fabrication of Silicon infiltrated Silicon Carbide (SiSiC) components by a hybrid additive manufacturing process. Selective laser sintering of polyamide powders was used to 3D print a polymeric preform with controlled relative density, which allows manufacturing geometrically complex parts with small features. Preceramic polymer infiltration with a silicon carbide precursor followed by pyrolysis (PIP) was used to convert the preform into an amorphous SiC ceramic, and five PIP cycles were performed to increase the relative density of the part. The final densification was achieved via liquid silicon infiltration (LSI) at 1500 • C, obtaining a SiSiC ceramic component without change of size and shape distortion. The crystallization of the previously generated SiC phase, with associated volume change, allowed to fully infiltrate the part leading to an almost fully dense material consisting of β-SiC and Si in the volume fraction of 45% and 55% respectively. The advantage of this approach is the possibility of manufacturing SiSiC ceramics directly from the preceramic precursor, without the need of adding ceramic powder to the infiltrating solution. This can be seen as an alternative AM approach to Binder jetting and direct ink writing for the production of templates to be further processed by silicon infiltration.

Electrified methane steam reforming on a washcoated SiSiC foam for low‐carbon hydrogen production

“…A surface to volume ratio ( Sv ) of 740 m −1 was calculated using the model developed by Ambrosetti et al 32 Figure 2 presents the XRD pattern of the foam. The result shows the presence of both SiC (PDF#49–1428) and Si phase (PDF#75–0589) 33 …”

“…The result shows the presence of both SiC (PDF#49-1428) and Si phase (PDF#75-0589). 33 The results of catalyst loading per deposition step during the washcoating process are shown in Figure 3. The final catalyst loading on the foam was 2.2 g after seven repeated coating steps.…”

High‐strength Si–SiC lattices prepared by powder bed fusion, infiltration‐pyrolysis, and reactive silicon infiltration

“…The newly developed hybrid technique 21,22,40 leverages a combination of 3D printing of polymer powders, precur-sor infiltration, pyrolysis, and LSI to produce complex ceramic 3D architectures. The process begins with the PBF technology to create a polyamide preform with high microporosity.…”

Straightforward Design Strategy toward 3D Near‐Net‐Shape Stoichiometric SiC Parts

“…[25] However, a major drawback is the incredible difficulty to overcome the problems (in terms of process parameters and phase compositions) linked to conventional debinding and densification stages: [13,22] very high temperatures (can be more than 2000 °C) and high pressures, dimensional restrictions, significant presence of residual silicon (Si) and/or carbon (C), use of sintering additives leading to impurities, and/or identification of amorphous phases. Reaction bonding by molten silicon infiltration [26][27][28] -achieved by a capillary force between silicon and a carbon-based porous preform-remains the most effective densification process according to the short processing time and the relatively low temperature (above the melting point of silicon, 1410 °C) [29] compared with traditional sintering methods. However, major issues such as the high parametric sensitivity, the exothermicity of the reaction between molten silicon and carbon, and the permeability reduction implied by SiC formation complicate the infiltration and conversion process.…”