Photopolymerization-based additive manufacturing of ceramics: A systematic review

Journal of Advanced Ceramics 2021, 10(3): 0–0 https://doi.org/10.1007/s40145-021-0468-z ISSN 2226-4108 CN 10-1154/TQ Review Photopolymerization-based additive manufacturing of ceramics: A systematic review Sefiu Abolaji RASAKIa,b, Dingyu XIONGa, Shufeng XIONGa, Fang SUa, Muhammad IDREESa, Zhangwei CHENa,c,* a Additive Manufacturing Institute, Shenzhen University, Shenzhen 518060, China Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China c Guangdong Key Laboratory of Electromagnetic Control and Intelligent Robotics, College of Mechatronics and Control Engineering, Shenzhen University, Shenzhen 518060, China b Received: December 30, 2020; Revised: February 2, 2021; Accepted: February 28, 2021 © The Author(s) 2021. Abstract: Conversion of inorganic–organic frameworks (ceramic precursors and ceramic–polymer mixtures) into solid mass ceramic structures based on photopolymerization process is currently receiving plentiful attention in the field of additive manufacturing (3D printing). Various techniques (e.g., stereolithography, digital light processing, and two-photon polymerization) that are compatible with this strategy have so far been widely investigated. This is due to their cost-viability, flexibility, and ability to design and manufacture complex geometric structures. Different platforms related to these techniques have been developed too, in order to meet up with modern technology demand. Most relevant to this review are the challenges faced by the researchers in using these 3D printing techniques for the fabrication of ceramic structures. These challenges often range from shape shrinkage, mass loss, poor densification, cracking, weak mechanical performance to undesirable surface roughness of the final ceramic structures. This is due to the brittle nature of ceramic materials. Based on the summary and discussion on the current progress of material–technique correlation available, here we show the significance of material composition and printing processes in addressing these challenges. The use of appropriate solid loading, solvent, and preceramic polymers in forming slurries is suggested as steps in the right direction. Techniques are indicated as another factor playing vital roles and their selection and development are suggested as plausible ways to remove these barriers. Keywords: ceramics; photopolymerization; stereolithography; additive manufacturing; 3D printing; polymer-derived ceramics 1 Introduction Ceramics are the materials with appreciable refractory properties [1]. This has made them relevant for a wide * Corresponding author. E-mail: range of applications which include mechatronics, aerospace, energy industries, bioengineering, construction, and nanotechnology [2]. However, ceramics are materials with high brittleness and hardening [3]. This has limited their applications in the field of advanced technologies where complex geometric structures are needed to be manufactured. Various conventional methods for shaping and tuning solid structures of ceramics have been www.springer.com/journal/40145 2 J Adv Ceram 2021, 10(3): 0–0 developed to date. Examples are tape casting, dry pressing, casting, and injection molding [4,5]. Despite the effectiveness of those approaches, the use of molds generally inflates the cost of production. More importantly, when it comes to the production of highly complex structures, limitation arises with the use of conventional methods. Based on the above, research attention has been widely shifted to the use of additive manufacturing (AM) techniques for the fabrication of ceramics. This is due to fact that AM offers (a) highly flexible design of complex structures, (b) integral manufacturing of complex components, (c) material waste minimization, (d) cost-effective production, and (e) short product lead time [6]. It is worth noting that there are different types of AM techniques depending on their energy sources and material requirements [6]. However, from the operation principle and material requirement perspectives, AM techniques can be generally classified as extrusion and jetting-based, photopolymerization-based, and powder sintering/melting-based techniques. They offer different advantages and benefits as discussed elsewhere [6]. For example, selective laser sintering (SLS) has been recently demonstrated for printing Al2O3 ceramics with poly-hollow microspheres [7,8]. It was claimed that the technique offers structures with porosity of about 72.41%, making them suitable for catalytic and bio-engineering applications. Nonetheless, photopolymerization-based additive manufacturing (photopolymerization-based AM) techniques are highly versatile in equipment setup and material requirements, and are able to produce parts with the highest resolution [9]. They are extensively studied and also considered the most promising AM technology in ceramic fabrication and hence become the focus of this review. In this review, a number of major photopolymerization-based AM techniques used for ceramic production are discussed and the relevant working principles, material, and technical requirements are compared in detail. Key challenges and problems associated are also summarized with possible solutions raised. Photopolymerization-based AM is a series of techniques in which application of light (mostly in ultraviolet range) is used to trigger photochemical reaction and shaping [10]. Among the various types of AM techniques, photopolymerization-based AM is the first AM technique invented dated back to the 1980s, which was originally used for rapid prototyping of 3D polymeric components [11]. Only since the 1990s, the techniques then were applied in the photopolymerization of ceramic– polymer suspension mixtures into ceramic structures [6]. Examples of the photopolymerization-based AM techniques are stereolithography (SL), digital light processing (DLP), two-photon polymerization (TPP), liquid crystal display (LCD) printing, continuous liquid interface production (CLIP), multi-jet printing (MJP), holographic 3D printing technology, and their derivatives [6,12–14]. These approaches normally offer structure with high feature resolution and surface quality. The photopolymerization-based AM-derived components are often found superior to that of other kinds of AM techniques (e.g., fused deposition modeling (FDM), direct ink writing (DIW), inkjet printing (IJP), selective laser sintering/melting (SLS/SLM), laser engineered net shaping (LENS) in term of structure engineering [15–21]. This is due to the ability of the photopolymerization-based AM techniques to produce materials with high resolution and complex structures. From the material processing perspective, photopolymerization-based AM techniques are mainly used to process slurries containing photoinitiator and ceramic– polymer matrix as feedstock [6]. The efficiency of most of these approaches (i.e., SL, TPP, DLP, LCD, CLIP, MJP) primarily relie (...truncated)