Ceramic Industry

CRADA Partnership Advances SiC Armor

June 1, 2004
Cooperative Research and Development Agreements (CRADAs) were established and authorized under the Federal Technology Transfer Act of 1986 as a vehicle to improve the transfer of commercially useful technologies from federal laboratories to the private sector. Since then, CRADAs have proven to be a crucial tool in developing and improving a variety of high-tech products-including ceramic armor.

A PS-SiC armor tile. Photo courtesy of Superior Graphite, Chicago, IL.
One such CRADA between Superior Graphite, based in Chicago, Ill., and Idaho National Engineering and Environmental Laboratory (INEEL), Idaho Falls, Idaho, has been developing improved silicon carbide (SiC) powders and processes to make advanced lightweight armor tiles to effectively protect future military vehicles. (The INEEL is the sole manufacturing base for the heavy armor solution for the M1 main battle tank.) Although SiC-based armor material is not a new discovery, the traditional processes of hot pressing and post hot isostatic pressing make the current commercially available pressure-assisted-densified (PAD) SiC an expensive material to be deployed extensively for armor applications. The Superior Graphite/INEEL partners have developed a low-cost pressureless sintering (PS) process for SiC armor material that meets the ballistic requirements of increasing threat levels of armor-piercing projectiles, while also weighing less than some conventional armor materials, such as alumina. The resulting PS-SiC armor material offers performance equivalent to current PAD-SiC, but at less than 60% of the cost of typical PAD-SiC.

Figure 1a. Ballistic limit behavior of various ceramic tiles.
Figures 1a and 1b show the results of ballistic tests performed on the PS-SiC armor tiles by the Armor Mechanics Branch at the U.S. Army Research Lab, Aberdeen Proving Ground, Harford County, Md. The tests indicated that the lower-cost PS-SiC offers ballistic performance that is within 97% of that of one brand of expensive PAD-SiC and that outperforms other brands of PAD-SiC and silicon nitride (Si3N4). The CRADA partners expect the lower-cost PS-SiC to become a popular choice of high-performance armor materials for future light-armored military vehicles, positioned between heavier alumina and more expensive and brittle boron carbide materials.

Figure 1b. Ballistic limit ws. areal density.
The Superior Graphite/INEEL research team continues to work on improving the ballistic performance of the silicon carbide ceramic, and they are also developing a process to fabricate ceramic in a conformal configuration to meet military demand. One example is a hard-particle-reinforced SiC matrix composite that potentially offers improved ballistic performance. The research team is also investigating the possibility of extending the process to boron carbide to gain further reductions in the overall weight of ceramic armor systems.

For more information about these developments, contact Superior Graphite at (312) 559-2999 or (800) 325-0337, e-mail CustomerServiceUSA@SuperiorGraphite.com , http://www.superiorgraphite.com ; or contact the INEEL at (800) 708-2680, e-mail info@inel.gov , http://www.inel.gov . For information about other CRADA opportunities, visit http://www.federallabs.org .