No matter how rapidly a 3D printer can produce a green ceramic part, there is always the question of sintering the component, which can take several hours. Now, however, a team from the University of Maryland (UMD) Department of Materials Science and Engineering has come up with an innovative approach for speeding up the sintering process, which could decrease production rates for ceramics AM substantially.
The sintering process has existed for thousands of years and is an integral part of ceramics manufacturing, as it transforms green parts into dense and strong final products. Conventional sintering, however, comes with a certain challenge: it can take hours to sinter a part. As the research team points out, heating up a furnace can itself take hours as can the baking stage. This duration has posed challenges for certain ceramics applications, including the production of solid-state batteries. Other, more advanced sintering methods, like microwave-assisted sintering, spark plasma sintering and flash sintering are either prohibitively expensive or only compatible with specific materials.
Considering these hurdles, the team from UMD set out to develop a new sintering method which could speed up ceramics post-processing and facilitate ceramic additive manufacturing and other types of production. The process is an ultrafast high-temperature sintering technique that can sinter ceramic parts over 1,000 times faster than traditional furnace sintering. The process is capable of high heating and high cooling rates, good temperature distribution and can reach temperatures up to 3,000 degrees Celsius. The research team says the technology can sinter ceramic parts in less than 10 seconds.
Liangbing Hu, research lead and the Herbert Rabin Distinguished Professor of the A. James Clark School of Engineering and Director of the Center for Materials Innovation, explained: ”With this invention, we ‘sandwiched’ a pressed green pellet of ceramic precursor powders between two strips of carbon that quickly heated the pellet through radiation and conduction, creating a consistent high-temperature environment that forced the ceramic powder to solidify quickly. The temperature is high enough to sinter basically any ceramic material. This patented process can be extended to other membranes beyond ceramics.”
The sintering approach will be commercialized through a UMD spinoff company called HighT-Tech LLC. Not only can the process dramatically speed up ceramics production, but it can also help to drive advances in AI-guided materials discovery.
“Ultrafast high-temperature sintering represents a breakthrough in ultrafast sintering technologies, not only because of its general applicability to a broad range of functional materials, but also due to a great potential of creating non-equilibrium bulk materials via retaining or generating extra defects,” added Jian Luo, a professor at UC San Diego that collaborated on the project.
Xiaoyu Zheng, an assistant professor at UCLA, concluded: ”We are delighted to see the pyrolysis time reduced from tens of hours to a few seconds, preserving the fine 3D printed structures after fast sintering.” The full research study was published in the journal Science and can be found here.