Two UMR researchers are working to better prepare the military against attacks by improving the materials for missile components such as nozzles.
Dr. Greg Hilmas, assistant professor of ceramic engineering, and Dr. Bill Fahrenholtz, assistant professor of ceramic engineering, are developing ultra-high-temperature ceramics to make missile nozzles stronger and more resistant to heat and thermal shock.
"When a missile has been launched, there are various stages of its flight trajectory at which you can attempt to shoot it down, but you have a limited set of options," says Hilmas. "You need missiles with some pretty serious propulsion capability moving at a good clip. This is when our nation’s defense industry needs the highest melting temperature materials to survive in a missile environment that contains extremely hot propellants."
Receiving $400,000 over a three-year period from the U.S. Army Space and Missile Defense Command, Hilmas and Fahrenholtz are beginning the effort to create a new material using silicon carbide that can withstand these extremely high temperatures.
The UMR researchers are going to study why certain materials perform better under the high-temperature and high-stress conditions of a thermal shock environment. Thermal shock is what occurs when materials heat up or cool down too quickly and can’t handle the stress load. "If you take a glass cup from the dishwasher when it is really hot and run it under cold water it will shatter. If you do the same with a Pyrex baking dish it doesn’t because that material is designed to have good thermal shock resistance," says Hilmas. "When a missile lights off it is going from room temperature to about 3,000 degrees Celsius in about one second and thermal shock is an issue."
"We will be attempting to develop silicon carbide ceramics that will have better thermal shock resistance than any other ceramic silicon carbide that has ever been made," says Fahrenholtz. "Currently, the Army uses metals on missile nozzles, and using ceramics would make a big improvement."
During the first year of research Hilmas and Fahrenholtz hope to validate the approach of using silicon carbide and start testing and creating specific materials. At the end of the third year, they plan to present the Army with actual samples along with a set of design criteria for the creation of novel ultra-high-temperature ceramic materials that can be used for missile nozzles. Ultimately they would like to see the material tested in a real missile nozzle, says Fahrenholtz.