While still young, 4D printing is making waves in the industry with its programmatic structures and reactions to stimuli. This opens up a lot of applications for many products, such as foldable and un-foldable structures or heat-sensitive materials. Sadly, one of the current problems facing 4D printing is that of a lack of materials. To remedy this, researchers City University of Hong Kong are presenting their 4D printed ceramics consisting of a mixture of polymers and ceramic nanoparticles for a ceramic print that can stretch and reform.
The team initially started out with a stretched 3D printable version of the objects they wanted to develop. These original precursors served as good initial points that could stretch up to 3 times their original size. Like many elastic objects, they could return to their original shape once released. Next, the team placed these thoroughly tested prints for heat treatment, turning them into ceramics.
“The whole process sounds simple, but it’s not,” said Professor Lu Jian, the mechanical engineer who led the research. “From making the ink to developing the printing system, we tried many times and different methods. Like squeezing icing on a cake, there are a lot of factors that can affect the outcome, ranging from the type of cream and the size of the nozzle, to the speed and force of squeezing, and the temperature.”
4D Printed Ceramic Nanoparticles
One of the main problems with 4D printing ceramics is that of the high melting points, which make them difficult to deform. While the plastics are easier to mold and contort on a micro level, ceramics can prove tricky. It took more than two-and-a-half years for the team to overcome the limitations of the existing materials and develop their 4D ceramic printing system.
The researchers went through two different shaping processes in their study. In the first, they 3D printed the ceramic precursors along with the substrate using novel ink. They stretched the substrate using a biaxial stretching device. Then, they printed the joints for connecting the precursors and placed the result on the stretched substrate. With the digital control of time and release for the stretched substrate, the materials morphed into the shape they intended it to.
In the second process, they printed the design pattern directly onto the stretched ceramic precursor. It was then released under computer-programming control and underwent the self-morphing process like the previous version.
The researchers believe it can have massive implications for how we design electro-magnetic components. Certain parts don’t fare well with metal structures, causing magnetic interference, so designers often use ceramics instead. Similarly, it could be great for producing shape-shifting, high-temperature components in aerospace applications.
Featured image courtesy of City University of Hong Kong.