New laser-fabricated ceramics from North Carolina State researchers demonstrate the ability to endure the ultra-hot temperatures common to nuclear power, jet engines, and spacecraft.
The new manufacturing process is extremely versatile, capable of being applied to coatings, tiles, or even complex 3D designs. From power to portability, to waste, the new method offers significant improvements over traditional furnaces.
Sintering Liquid Polymer
“Sintering is the process by which raw materials – either powders or liquids – are converted into a ceramic material,” says co-author Cheryl Xu, professor of mechanical and aerospace engineering at North Carolina State University. “For this work, we focused on an ultra-high temperature ceramic called hafnium carbide (HfC).”
In a traditional process, a furnace capable of reaching at least 2,200 degrees Celsius is required to sinter HfC. The new laser process greatly reduces the time, effort, and energy required to make the durable ceramic.
Laser Hardening
Beginning with a liquid polymer held in an inert environment, such as a vacuum chamber, the process utilizes a 120-watt laser to sinter the liquid into a solid ceramic. The technique allows for coating existing objects, like the carbon composites common to space or hypersonic vehicles, before hardening with the laser.
“Because the sintering process does not require exposing the entire structure to the heat of the furnace, the new technique holds promise for allowing us to apply ultra-high temperature ceramic coatings to materials that may be damaged by sintering in a furnace,” Xu says.
Additionally, the process can be used in 3D printing, commercially known as “additive manufacturing,” by adapting it with a method reminiscent of stereolithography. Such a variant relies on a table-mounted laser and a bath of liquid polymer, from which the laser effectively “draws” the object in thin slices that are incrementally built up into a final shape. As the laser solidifies layers on top of the polymer bath, the table lowers deeper into the liquid while a blade moving across the top smoothes out the surface.
“It’s actually a bit of an oversimplification to say that the laser is only sintering the liquid precursor,” Xu says. “It is more accurate to say that the laser first converts the liquid polymer into a solid polymer and then converts the solid polymer into a ceramic. However, all of this happens very quickly – it’s essentially a one-step process.”
Tests Prove Laser Technique Effective
In tests, the end product was a crystallin, phase-pure HfC. “This is the first time we know of where someone was able to create HfC of this quality from a liquid polymer precursor,” Xu explained. “And ultra-high temperature ceramics, as the name suggests, are useful for a wide range of applications where technologies must withstand extreme temperatures, such as nuclear energy production.”
Beyond producing full objects, the process worked exceptionally well as a coating for carbon-fiber reinforced carbon composites, bonding to the underlying structure without peeling away.
“The HfC coatings on C/C substrates demonstrated strong adhesion, uniform coverage, and potential for use as thermal protection and an oxidation-resistant layer,” Xu says. “This is particularly useful because, in addition to hypersonic applications, carbon/carbon structures are used in rocket nozzles, brake discs and aerospace thermal protection systems such as nose cones and wing leading edges.”
Improving Production
In early testing, the laser process has proven more efficient than traditional sintering methods. What would take older processes hours or days, the new method can accomplish in minutes or even seconds. Its focused energy use also significantly reduces power requirements while more efficiently converting mass to ceramic at a 50% rate compared to 20-40% for traditional methods. While the process requires an inert environment, the vacuum chamber and printing equipment are much smaller and more portable than a large furnace.
“We are excited about this advance in ceramics and are open to working with public and private partners to transition this technology for use in practical applications,” says Xu.
The paper “Synthesis of Hafnium Carbide (HfC) via One-Step Selective Laser Reaction Pyrolysis from Liquid Polymer Precursor” appeared on May 14, 2025, in the Journal of the American Ceramic Society.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.