Researchers from the City University of Hong Kong (CityU) have successfully developed the world's first-ever 4D printing for ceramics that can be used to create complex, shape-changing objects.
4D printing is conventional 3D printing combined with the additional element of time as the fourth dimension, where the printed objects can re-shape or self-assemble themselves over time with external stimuli, such as mechanical force, temperature, or a magnetic field.
• The researchers made use of the elastic energy stored in the stretched precursors for shape morphing. When the stretched ceramic precursors are released, they undergo self-reshaping.
• After heat treatment, the precursors turn into ceramics. Ceramic has a high melting point, so it is difficult to use conventional laser printing to make ceramics.
• The resultant elastomer-derived ceramics are mechanically robust. They can have a high compressive strength-to-density ratio, and they can come in large sizes with high strength compared to other printed ceramics.
• The existing 3D-printed ceramic precursors, which are usually difficult to deform, also hinder the production of ceramics with complex shapes.
• To overcome these challenges, researchers developed a novel 'ceramic ink', which is a mixture of polymers and ceramic nanoparticles.
• Following are the features of the new ceramic ink:
- The 3D-printed ceramic precursors printed with this novel ink will be soft and can be stretched three times beyond their initial length.
-These flexible and stretchable ceramic precursors will allow complex shapes, such as origami folding.
- Hence, with proper heat treatment, ceramics with complex shapes can be made.
About the Research Team
The research team was led by Professor Jian Lu, Vice-President (Research and Technology) and Chair Professor of Mechanical Engineering, who is a distinguished materials scientist with research interests ranging from fabricating nanomaterials and advanced structural materials to the computational simulation of surface engineering.
It took the team more than two and a half years to overcome the limitations of the existing materials and to develop the whole 4D ceramic printing system.
With the development of the elastic ceramic precursors, the research team has achieved one more breakthrough by developing two methods of 4D printing of ceramics.
1. In the first shaping method, a 3D-printed ceramic precursor and substrate were first printed with the novel ink. The substrate was stretched using a biaxial stretching device and joints for connecting the precursor were printed on it. The precursor was then placed on the stretched substrate. With the computer-programmed control of time and the release of the stretched substrate, the materials morphed into the designed shape.
2. In the second method, the designed pattern was directly printed on the stretched ceramic precursor. It was then released under computer-programming control and underwent the self-morphing process.
The findings of the research were published in the latest issue of top academic journal Science Advances under the title "Origami and 4D printing of elastomer-derived ceramic structures."
The printed ceramic precursors can be used in the manufacture of electronic devices. Ceramic materials have much better performance in transmitting electromagnetic signals than metallic materials.
Further, with the arrival of 5G networks, ceramic products will play an even more important role in the manufacture of electronic products. The artistic nature of ceramics and their capability to form complex shapes also provide the potential for consumers to tailor-make uniquely designed ceramic mobile phone back plates.
The innovation can also be used in the aero industry and for space exploration, as ceramic is a mechanically robust material that can tolerate high temperatures.