WEST LAFAYETTE, Ind. — Researchers at the Purdue Applied Research Institute (PARI) are developing additive manufacturing processing methods to 3D print dark ceramics — materials that can withstand the harsh conditions of hypersonic flight — into complex shapes for hypersonic vehicle components. The goal is to 3D print these components at scale to improve efficiency and performance.
Rodney Trice, professor in the College of Engineering’s School of Materials Engineering and the thrust lead in ceramic processing at PARI’s Hypersonics Advanced Manufacturing Technology Center (HAMTC), is leading the effort to enhance these materials for the additive manufacturing process.
Dark ceramics are ideal materials for hypersonic vehicle components because they’re less likely to crack or degrade due to extreme atmospheric conditions. To manufacture hypersonic components made with ceramics, Trice and his team use 3D printers housed at HAMTC that employ a process called digital light processing. These printers have a projector that shines ultraviolet (UV) light on a thin layer of slurry composed of ceramic powder and resin. The UV light then cures or hardens that layer, locking the powder into place.
With digital light processing, the component is built layer by layer, Trice said. “This allows you to produce intricate designs and geometries with very smooth surfaces and with a level of precision at the micron level,” he said. “Through this process, we have succeeded in printing a variety of shapes, such as sharp cones and hemispheres, which are used to build a hypersonic vehicle.”
The challenge behind 3D printing dark ceramics stems from how their color interacts with the UV light the 3D printer projects. A light-colored ceramic, such as alumina, will reflect and scatter the light, hardening the entire layer at once. Dark ceramics, on the other hand, tend to absorb that light and therefore inhibit the curing process.
“Because dark powders absorb the UV light that would be necessary to cure the material, we cannot form as thick of a layer,” said Trice. “Therefore, we get cure depths that are too thin, which then negatively impacts the time it takes to build each part.”
Matthew Thompson, a materials engineering doctoral candidate and recipient of a National Defense Science and Engineering Graduate Fellowship, and Dylan Crump, ceramics research engineer at HAMTC, have been working with Trice to investigate resin systems, surface treatments and other approaches to increase the cure depths.
“We’ve been operating essentially as a research and development test bed for these materials,” said Thompson. “We’ve been tuning properties and performing surface modifications to improve their performance and enhance the printing process.”
Trice, Thompson and Crump are also working to eliminate any problems during the postprocessing phase, which becomes even more challenging as the printed parts increase in size. With larger components, issues like delamination — the part peeling or separating into layers — or cracking become more of a risk. They want to ensure that these risks don’t compromise components as they transition from a small-scale printer to a larger one.
“What we’re trying to do is find solutions for how we can either set up a pipeline to make these parts or find strategies that actual stakeholders can use,” said Thompson. “So, it gives people a starting point to save time on the research and development for any new system.”
This effort is one of five projects funded by the Office of the Secretary of Defense Manufacturing Science and Technology Program, partnering with the Naval Surface Warfare Center, Crane Division, and the National Security Technology Accelerator’s Strategic and Spectrum Missions Advanced Resilient Trusted Systems.
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Media contact: Lindsey Macdonald, macdonl@purdue.edu