On January 13, 2023, Shenzhen QIYU Technology*** and researchers from the Shenzhen Graduate School of Tsinghua University published a paper entitled "Additivemanufacturing".4dprinting of ceramicstructuresThe 4D printing strategy of complex ceramic structures has been proposed and successfully realized, and the controllable shape deformation of ceramic structures has been realized by accurately adjusting the solid content and printing path of ceramic materials.
Original link: QIYU Technology official website:
About the study
4D printing enables controllable shape deformation with 3D printing and enables multiple possibilities for complex shape design. However, 4D printing is often applied to soft materials that are easily deformed. And ceramics are hard and brittle in nature, which hinders their development in 4D printing. In this study, the stress mismatch of printed ceramics during the sintering process was used to realize the 4D printing of ceramic structures. In general, the shrinkage of 3D printed ceramics after sintering is inversely proportional to the solid content of the ceramic material used. The QIYU team printed double-layer zirconia (ZRO2) ceramics with high solid content on the bottom layer and low solids content on the top layer, so that the direction of the internal stress of the sintering shrinkage rate was consistent with the axial direction of the low-shrinkage material, and the shape of the ceramic was changed from a plane to a curved structure. In this process, the researchers selected different printing processes to customize the shape deformation behavior of the ceramic structure. Finally, by programming the solid content and printing path of the ceramic material, 4D printed ceramic flowers with various characteristics were realized.
Figure 1: 4D printing of ceramic structures using the direct-writing and sintering method (A, B) mixing ZRo2 nanoparticles with UV resin in different proportions (C) UV material ink containing uniformly dispersed ZRO2 nanoparticles (D) 3D printing of ceramic chips equipped with DIW technology and UV curing treatment using dual nozzles (E) 3D printing of ceramic chips sintered into 4D printed ceramic structures.
Fig. 2: Self-deformation of the ceramic bilayer during sintering (a) printing of the double-layer ceramic square with different paths (b) change in the shape of the double-layer ceramic square after sintering (c) comparison of the ceramic square before and after sintering (d) geometry of the double-layer ceramic rectangle after sintering (e) geometry of the double-layer ceramic ellipse after sintering.
Fig. 3: 4D printing of ceramic flowers by programming printing paths: (a) the top layer of double-layer ceramics is printed in different paths, (b) the shape changes of various double-layer ceramic polygons after sintering, (c) the top view of the stacked ceramics before and after sintering, and (d) the side view of the stacked ceramics before and after sintering.
Fig. 4: 4D printing of ceramic flowers by adjusting the solid content of UV ink: (A) the shape changes of various double-layer ceramic polygonal and laminated ceramic structures after sintering (B) the microscopic morphology of double-layer ceramics after sintering, and (c) the flower geometry imitated by the 4D printed ceramic structures.
Conclusions of the study
In this paper, the 4D printing technology of ceramic structures is proposed and studied. Firstly, the shrinkage of ink sintered ceramics with different solid content was estimated. Then, the double-layer ZRO ceramics were prepared using DIW technology. We found that during the sintering process, the shrinkage mismatch between the top and bottom layers led to a change in the shape of the double-layer ceramic. Therefore, the 4D printing of ceramics is achieved by sintering-derived double-layer self-deformation. Both the solid phase content and the printing path of ceramic inks affect the self-deformation process of ceramics. By cropping the above two parameters, a 4D printed ceramic structure that mimics the geometry of a flower can be obtained. In this way, 4D printing provides a feasible strategy for designing complex ceramic structures in the DIW sintering process. The 4D printed ceramic structures presented in this paper also show a programmable self-deformation strategy, which is a promising bottom-up method for advanced ceramic fabrication.