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Materials Science in Additive Manufacturing Ceramic vat photopolymerization

For a ceramic slurry to be compatible and printable Pre-ceramic polymers can be directly processed
with VPP, it should have some common features and through sol-gel methods, offering advantages such as
requirements: simplified handling, no drying issues, shorter processing
(i) Composition. Ceramic slurries consist of ceramic times, elimination of flammable solvents, and superior
powders (40 – 60 vol.%), UV-curable resins solution stability compared to ceramic powders or pastes.
(e.g., acrylates), photoinitiators, and dispersants. A critical aspect of pre-ceramic polymer processing is
For instance, alumina-based slurries with optimized crosslinking, which is essential for ceramic formation.
particle size distributions (coarse, medium, and fine Adjusting the molecular weight of these polymers enables
powders) improve packing density and reduce defects precise control over rheological properties, an area of
(ii) Rheology. Low viscosity (<3 Pa·s) is critical for layer ongoing research. The rheological behavior of pre-ceramic
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uniformity, achieved by balancing solid loading and polymers is particularly crucial when they serve as binders
dispersant content. High solid loading (>50 vol.%) for ceramic powders in composite printing applications.
ensures structural stability but risks increased viscosity. Silicon-based pre-ceramic polymers are widely utilized in
Sedimentation and agglomeration of particles can SL for fabricating intricate structures due to their stability.
compromise print quality, necessitating continuous These photocurable inorganic polymers transform into
agitation high-strength, chemically inert ceramics upon pyrolysis in
(iii) Photoreactivity. Slurries must allow sufficient UV inert atmospheres. The incorporation of active or passive
penetration for curing. Nanoparticle additives fillers allows for the creation of diverse advanced ceramic
2,25
(e.g., SiC and YAG) can enhance properties but may phases. An optimal pre-ceramic polymer should exhibit
scatter light, requiring precise formulation. high molecular weight, suitable rheological properties,
In recent years, the persistent challenges in formulating good solubility for shaping, and functional groups that
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ceramic slurries and optimizing VPP processes have facilitate curing and crosslinking. Table 2 presents a
prompted the exploration of alternative ceramic feedstock summary of the commonly used organosilicon pre-
materials. Among these, pre-ceramic polymer-derived ceramic polymers, along with their backbone structures,
ceramics have gained significant research interest due to synthesis methods, and resulting ceramics.
their superior processability during shaping operations In the VPP process, photopolymerizable monomers
and outstanding material properties. Compared to along with a small amount of photoinitiator and other
conventional powder-based ceramic processing, these additives are used to make a slurry/blend of appropriate
polymer-derived materials demonstrate remarkable rheological properties. Ceramic particles of sizes down to
thermal stability along with enhanced mechanical micro/nanometers can also be incorporated into it for the
characteristics, including higher strength and improved fabrication of composite ceramics before printing. The
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fracture toughness. processing and printing steps of pre-ceramic polymers

Table 2. List of commonly used pre‑ceramic polymers for vat photopolymerization and ceramization along with their synthesis
methods and respective derived ceramics
Pre‑ceramic polymer Derived ceramics Applications Ref.
Polysilanes SiC Photoresists, semiconductors, 26-28
(–R R Si–) precursors to polycarbosilane synthesis
1 2
Polycarbosilane SiC Electric or photo-conductors, 29-33
(–R R Si–C–) photoresists, nonlinear optical materials
1 2
Polysilazane Si N and SiCN Barrier for heat exchanger, 34-36
4
3
(–R R Si–N=) oxidation-resistant
1 2
Polysiloxane SiOC Biomedical, electronics, textile 37,38
(–R R Si–O–) chemistry
1
2
Poly (organosilylcarbodiimides) SiCN High-temperature ceramics, chemically 39,40
(–R R Si–N=C = N–) resistant
1
2
Polyborosilazane Borosilicate ceramics High-temperature ceramics, chemically 41-43
(–R R Si–N (R R B)–) such as SiCBN, SiBC, etc. resistant
4
3
2
1
Polyborosilane,
(–R R Si–B (R )–)
1
3
2
Polyborosiloxane
(–R R Si–O (R R B)–)
1 2 3 4
Volume 4 Issue 3 (2025) 8 doi: 10.36922/MSAM025200031