Controlling light absorption in digital light processing (DLP) via pigment incorporation offers a versatile approach to tuning curing dynamics, shrinkage behaviour, and mechanical performance in ceramic additive manufacturing. In this study, black pigment (BP) was systematically introduced into a silica-based photopolymer suspension to modulate optical attenuation and enhance the geometric fidelity, surface quality, and dimensional accuracy of printed parts. An optimal 2 wt% BP formulation reduced peeling forces by ≈40% and eliminated recoating resistance, enabling smoother layer separation and improved print stability. Cure uniformity was enhanced, suppressing overcuring artefacts and sharpening lateral features. The degree of polymer conversion increased from ≈50% (no pigment) to ≈76%, correlating with reduced early-stage mass loss during thermogravimetric analysis, indicating a more complete crosslinked network and reduced low-temperature volatilization. These effects led to significantly improved mechanical performance, with green strength reaching ≈36 MPa and sintered strength ≈12 MPa, alongside minimized shrinkage anisotropy (ΔZ–XY ≈ 0.12%). Microstructural and profilometric analyses confirmed improved microstructural integrity and surface quality, with lateral surface roughness reduced to ≈4 μm and cure-induced overgrowth eliminated. Cure depth tuning effectively confined light penetration, improving interlayer bonding and dimensional precision. A full-scale silica-based ceramic core printed with the optimized formulation preserved intricate features and achieved dimensional accuracy within ±0.5 mm after sintering. These findings demonstrate that, within the studied silica-based system, pigment-modified photopolymer formulations enable high-resolution, low-defect DLP ceramic printing, offering a scalable and reliable route for precision components in aerospace, investment casting, and high-temperature tooling. • Black pigment tuned light absorption in DLP ceramic printing, improving cure uniformity and resolution. • At 2 wt.% BP, peeling force dropped ~40%, recoating became resistance-free, and conversion rose to ~76%. • Green and sintered flexural strengths reached ~36 and ~12 MPa, respectively. • Porosity decreased, surface roughness reached ~4 µm Sa, and shrinkage anisotropy was reduced to ~0.12%. • A full-scale silica-based core achieved ±0.5 mm post-sintering accuracy in complex geometries.
Ozkan et al. (Wed,) studied this question.
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