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Materials Science in Additive Manufacturing Ceramic vat photopolymerization

starting from the primary precursors are shown in Figure 5. eliminate the need for crosslinking by providing sufficient
The final yield, y , of the ceramic is given as: structural support to maintain dimensional stability during
c
w processing.
y = w 1 0 (XII) 4. Post-processing and heat treatment
c

where y is the ceramic yield, w is the weight of ceramic Post-curing represents a critical secondary processing
1
c
residue, and w is the original weight of the specimen step that enhances the consolidation of incompletely
0
before pyrolysis. polymerized resin components within fabricated
structures. This treatment significantly improves the
The cross-linking of pre-ceramic polymers is a critical
step, typically achieved through radiation or catalytic mechanical performance and structural integrity of
printed components. However, substantial dimensional
methods at low temperatures. Polymers with a high degree changes occurring during post-processing remain a key
of crosslinking exhibit improved ceramic yield, which
is essential for maintaining structural integrity during challenge in ceramic photopolymerization techniques.
subsequent processing. Most pre-ceramic polymers feature Consequently, comprehensive characterization of post-
an inorganic backbone with hydrogen atoms or organic curing behavior is fundamental for minimizing geometric
substituents. These components either integrate into the distortion and improving dimensional accuracy in printed
ceramic residue or are released as volatile byproducts ceramic components.
during high-temperature pyrolysis. This conversion The curing shrinkage is primarily influenced by the
process involves gas evolution, isotropic shrinkage, and curing extent of the green-state material where higher
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pore formation, often leading to structural defects that curing degrees result in reduced shrinkage. The curing
compromise the final ceramic density. To mitigate these degree depends on process parameters such as laser power,
issues, incorporating fillers has become a primary approach layer pitch, scan pitch, and scanning speed. Increased laser
for producing bulk ceramic components with controlled power enhances crosslinking, improving curing depth and
dimensions. A variety of fillers – including polymeric, line width. Conversely, larger layers and scan pitches reduce
metallic, and ceramic materials in nano- or micro-scale curing by leaving more uncured resin, while faster scanning
forms – can be blended into pre-ceramic polymers to speeds decrease energy exposure per unit area. Laser
enhance their properties. Fillers play multiple functional power stability and resin photosensitivity (wavelength
roles and can be categorized as either reactive or passive. compatibility) further affect curing efficiency. Among
Passive fillers remain chemically stable throughout the these factors, laser power, layer pitch, and scan pitch play
entire process, showing no reactivity with the pre-ceramic dominant roles in determining the final curing degree.
polymer, ceramic residue, or processing atmosphere. Their
primary function involves facilitating gas release during The curing efficiency demonstrates an inverse
pyrolysis, which helps minimize dimensional shrinkage correlation with layer thickness, where the reduced spacing
while preventing crack formation and macroporosity between layers promotes greater overlap and minimizes
in the final ceramic product. In contrast, active fillers residual uncured resin. This relationship similarly
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chemically interact with both the gaseous byproducts of governs scan spacing effects, as wider intervals leave more
ceramization and the processing atmosphere, potentially materials uncured and consequently diminish curing
altering the composition of the resultant ceramic material. quality. Scanning velocity plays a crucial role, with faster
These reactive additives enable precise tuning of functional speeds reducing energy deposition per unit area and thus
characteristics, including electrical conductivity, thermal lowering curing effectiveness. Process stability emerges as
expansion behavior, and magnetic properties. Notably, another critical factor, where fluctuations in laser power
when pre-ceramic polymers contain substantial filler lead to inconsistent polymerization. The material’s inherent
content, the reinforcing effect of these additives may properties, particularly its photosensitivity and spectral

Figure 5. Processing steps involved to obtain ceramics from pre-ceramics
Abbreviations: R.T.: room temperature; T: temperature

Volume 4 Issue 3 (2025) 9 doi: 10.36922/MSAM025200031