3D printing of high-performance ceramics for hypersonic applications

Researchers at the Purdue Applied Research Institute (PARI) are working on new additive manufacturing methods for dark ceramics that can withstand extreme conditions and are suitable for hypersonic flight. The goal is to efficiently and scalably produce these high-performance ceramics in complex geometries to improve the performance of hypersonic vehicles.

Under the direction of Rodney Trice, professor in the School of Materials Engineering and expert in ceramic manufacturing processes at PARI’s Hypersonics Advanced Manufacturing Technology Center (HAMTC), research is being conducted into how these materials can be optimized for 3D printing. Dark ceramics are particularly resistant to cracking and degradation under extreme atmospheric conditions. They are produced using digital light processing (DLP), in which UV light is projected onto a thin layer of a ceramic slurry. This slurry consists of a ceramic powder and a resin, which is cured by the light and fixes the powder particles.

“This allows you to produce intricate designs and geometries with very smooth surfaces and with a level of precision at the micron level,” Trice 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.”

However, the interaction of dark ceramics with UV light poses a particular challenge. While light-colored ceramics reflect the light and cure evenly, dark ceramics absorb the light, which leads to insufficient curing depths and reduces the printing speed.

“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.”

To solve this problem, Matthew Thompson, a PhD student in materials engineering, and Dylan Crump, a ceramics research technician at HAMTC, are investigating different resin systems and surface treatments. These measures are intended to improve the curing depth and increase the printing speed. Another aim is to minimize potential sources of error in the post-processing process. The risk of delamination or cracking, which could compromise the structural integrity of the components, is particularly high with larger components.

Matthew Thompson, a materials engineering doctoral candidate and recipient of a National Defense Science and Engineering Graduate Fellowship, said: “We’ve been operating essentially as a research and development test bed for these materials. We’ve been tuning properties and performing surface modifications to improve their performance and enhance the printing process.”

“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 research project is one of five funded by the Office of the Secretary of Defense Manufacturing Science and Technology Program. It is being conducted in collaboration with the Naval Surface Warfare Center, Crane Division, and the National Security Technology Accelerator’s Strategic and Spectrum Missions Advanced Resilient Trusted Systems. The knowledge gained will serve as a basis for industrial applications in order to reduce the development effort for new systems.