Ceramics have a high melting point, making it difficult to use conventional laser printing to produce these materials. Existing 3D-printed ceramic precursors are also difficult to deform, preventing fabrication of ceramics with complex shapes.

Researchers at City University of Hong Kong overcame these barriers with a new 4D printing process for ceramics based on a novel ceramic ink. The 3D-printed ceramic precursors printed with this ink, a mixture of Printed ceramic origami mimicking the Sydney Opera House. Source: City University of Hong KongPrinted ceramic origami mimicking the Sydney Opera House. Source: City University of Hong Kongpolymers and ceramic nanoparticles, are soft and can be stretched three times beyond their initial length, allowing for the realization of complex shapes, such as origami folding.

The 4D printing process 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 over time with external stimuli. To achieve this, the researchers exploited 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.

The resultant elastomer-derived ceramics are mechanically robust with a high compressive strength-to-density ratio (547 MPa on 1.6 g cm-3 microlattice).

In one shaping method, a 3D-printed ceramic precursor and substrate were first printed with the new 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, and with computer-programmed control of time and the release of the stretched substrate, the materials morphed into the designed shape.

In another technique, the designed pattern was directly printed on the stretched ceramic precursor and then released under computer-programming control to undergo the self-morphing process.

The research is published in Science Advances.

To contact the author of this article, email shimmelstein@globalspec.com