Interlayer bonding in vat photopolymerization additive manufactured ceramics with enhanced mechanical properties

Vat photopolymerization (VPP) additive manufacturing, particularly stereolithographic (SLA) and digital light processing (DLP), has garnered significant attention owing to their high manufacturing resolution, excellent surface quality, and relatively fast build speeds. Despite these advantages, transitioning from conventional to AM of high performance ceramic presents substantial scientific and technological challenges. The mechanical properties of VPP fabricated ceramics are lower than those of the conventional method and are critically dependent on the elimination of processing defects, which can originate at multiple processes.

In addition to the ceramic suspension fabrication, the mechanical properties and densification of the ceramic are critically dependent on a multi-stage process chain, in which the stereolithographic parameters and the subsequent sintering schedule play a decisive role. The layer-by-layer approach of AM results in anisotropic characteristics and interlayer bonding weaknesses that are not present in isotropic bodies fabricated through conventional methods. The "interlayer," an inherent feature, serves as a potential flaw zone that can propagate during the sintering processes, ultimately compromising the density and mechanical integrity of the ceramic component. Inadequate or excessive polymerization can lead to the formation of interlayer defects, which become failure origins after the sintering process. However, at present, the stereolithographic process and the high temperature sintering process are treated as sequential, independent modules for parameter optimization. Without systematically addressing the origins and evolution of these interlayer weaknesses, performance enhancements will encounter bottlenecks.

Recently, a team of material scientists led by Rujie He from Beijing Institute of Technology and Keqiang Zhang Form Nanjing Tech University report interlayer bonding in vat photopolymerization additive manufactured ceramics with enhanced mechanical properties.

The team published their work in Journal of Advanced Ceramics on 24 March 2026.

“In this work, we introduce a novel perspective by reconceptualizing the interlayer zone as a dynamic evolutionary system that encompasses the VPP process, from stereolithographic to sintering. The final mechanical properties are dictated by the cross-process evolution of the interlayer, governed by the synergistic interplay between photopolymerization dynamics and sintering kinetics, specifically within this zone. Instead of passively minimizing defects, we propose an active strategy of cross-process synergistic control to facilitate the interlayer evolution. Specifically, an orthogonal experimental design is employed to optimize the key stereolithographic parameters, including irradiance, exposure time, and slicing thickness, to enhance the flexural strength and density by ensuring strong interlayer bonding. A particular emphasis is that layer thickness is the most pivotal factor. Subsequently, the sintering process is explored by constructing a sintering kinetic window and studying the effects of temperature and time on density, flexural strength and microstructure evolution. This work introduces a novel cross-process synergistic control strategy aimed at guiding interlayer evolution and establishes preliminary but crucial correlations between process parameters, interlayer structural evolution and mechanical property.” said Keqiang Zhang, associate professor at Nanjing Tech University. His main research focus is ceramic additive manufacturing.

“The principal contributions of this work are twofold. Firstly, it presents a concrete and effective processing way for the fabrication of high performance ZrO2 ceramics via VPP. Secondly, it proposes a novel framework that establishes relations between process parameters, interlayer structural evolution and mechanical properties. This work enhances our understanding of property development in VPP additive manufactured ceramic and paves the way for the integrated design of processes applicable to other material systems where an interlayer is essential.” said Rujie He, professor at Institute of Advanced Structure Technology, Beijing Institute of Technology (China), a senior expert whose research interests focus on the field of ceramic additive manufacturing.

Other contributors include Qiaoyu Meng, and Zhaoliang Qu from the Institute of Advanced Structure Technology, Beijing Institute of Technology (China).

About Author

Keqiang Zhang is an associate professor at Nanjing Tech University. His main research focus is additive manufacturing of ceramics. In recent years, as the first or corresponding author, he has published 20 SCI papers in journals such as Journal of Advanced Ceramics, Journal of Materials Science & Technology, and Additive Manufacturing. His single paper has received up to 340 citations, with a total of more than 3,700 Google Scholar citations in the past five years, and his h-index is 31. He has delivered 6 invited/keynote speeches at national and international academic conferences and chaired 3 conference sessions, and serves as a Youth Editorial Board Member for journals including Rare Metals, Journal of Inorganic Materials, and Additive Manufacturing Frontiers. He has been listed among the World's Top 2% Scientists by Elsevier for three consecutive years (2023~2025).

Funding

This work was supported by the National Natural Science Foundation of China(No. 52402084, 52275310) and the China Postdoctoral Science Foundation

(No. 2024M751646).

About Journal of Advanced Ceramics

Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen. JAC’s 2024 IF is 16.6, ranking in Top 1 (1/34, Q1) among all journals in “Materials Science, Ceramics” category, and its 2024 CiteScore is 25.9 (5/130) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508