3D printing of ceramic matrix composites: Strengthening and toughening strategies

Three dimensional (3D) printing, or additive manufacturing (AM) of ceramics has obtained broad attentions in recent years among industry and academia. However, ceramic materials inevitably suffer from their inherent brittleness and unexpected fracture. Thus, many researchers have developed various ceramic composites for diverse applications to overcome this drawback. In this review, versatile 3D printed ceramic composites are investigated, including carbonaceous materials reinforced ceramic matrix composites (CMrCMCs), metal reinforced ceramic matrix composites (MrCMCs), polymer reinforced ceramic matrix composites (PrCMCs), and ceramic reinforced ceramic matrix composites (CrCMCs), a particular focus is placed on scrutinizing how the added reinforcements strengthen and toughen the 3D printed ceramic composite structures. Based on the categories of four reinforcement phases and seven main 3D printing technologies, various ceramic strengthening and toughening mechanisms are discussed, and it was found that CrCMCs encompass the most sophisticated toughening strategies, such as phase transformation toughening, microcrack toughening, crack deflection and bridging, whiskers/fiber toughening, and in-situ toughening etc. Some specific 3D printing technologies such as coaxial extrusion, and material extrusion of ceramic ink and continuous fibers are introduced. Finally, summary and a perspective for future research work in 3D printing of strengthened and toughened ceramic composites are discussed.