Each year the U.S. Army invests in manufacturing development programs that provide new, groundbreaking capabilities for Soldiers. Despite the criticality and importance of these programs, many do not progress due to competing internal priorities and funding availability.
An example is nanoscale materials manufacturing, which uses highly complex materials to increase the performance of Army platforms. Along with support from Congress, the Army’s Manufacturing Technology program, or ManTech, provided resources to develop and mature nanoscale particle manufacturing to improve current capabilities and performance of penetrators, ballistic protection materials and flexible electronics. The ManTech program is executed by the U.S. Army Combat Capabilities Development Command — a major subordinate command of the Army Futures Command — with oversight from the Assistant Secretary of the Army (Acquisition, Logistics and Technology), Office of the Deputy Assistant Secretary of the Army for Research and Technology.
“Nanoscale particle manufacturing is more than just being able to create very small particles. Getting particles to the nanoscale can be a top down or bottom up approach. Current processes can either grow nanoparticles through wet chemistry methods or grind larger particles down to the nanoparticle scale through milling techniques,” said Dr. Peter Canales, CCDC Armaments Center Materials and Producibility Division. “It is the processes and technologies that enable us to control material properties that we are trying to bring into traditional manufacturing.”
Tungsten carbide has traditionally been used to make ballistic parts, including small to medium caliber penetrators, because of its high density, hardness and resistance to heat and wear. However, because tungsten carbide is so hard, it is difficult to machine into parts using traditional manufacturing. By preparing the tungsten as a powder and mixing it with carbon and other binder materials, the tungsten carbide is prepared using a wet chemical synthesis that “grows” the particles to size rather than grinding them down from larger particles.
“By mixing the particles in a solution versus blending dry powders manually, we can adjust it with greater precision and drive end performance, including density and hardness,” Canales said.
One of the binder materials used with tungsten carbide to make ballistic munitions is cobalt, which is classified as a possible carcinogenic. While there is less risk to exposure if the cobalt is undisturbed, its use in munitions increases the potential for fragments and powder residue to be dispersed. One of the goals of the nanoscale materials project is to develop and mature more environmentally friendly manufacturing processes to eliminate cobalt and reduce exposure risks on and off the battlefield.
Boron carbide is another promising material used for body armor plates for Soldiers to protect them and their vehicles from small arms fire and larger munitions. Boron carbide’s hardness makes it ideal for stopping projectiles while its light weight helps to minimize the load carried. The ManTech program is working with new suppliers using boron carbide to improve capacity, capability and overall supply chain resiliency.
As the Army develops novel materials to improve both ballistic materials and armor penetration, it is also exploring nanoscale particles for 3D printing of electronics. While traditional electronic printing is designed for rigid, flat substrates, 3D printing integrates electronics into printed structures that conform to complex and potentially flexible substrates. For example, a munition with a rounded interior requires a substrate that can bend and conform while maintaining performance, along with a conductive ink that is dense enough to maintain conduction. Silver ink, which is composed of nano to micron scale metallic particles, is a conductive ink used in flexible electronic printing. The metallic powder is mixed with solvent liquids, which controls the flow, density and conductivity, making it ideal for flexible electronic printing.
While several companies currently produce conductive inks for electronic printing, there was only one manufacturer that met certain desirable performance parameters for silver ink for the Department of Defense. The manufacturer produced silver ink for commercial and defense applications, but it discontinued producing the ink, which affected ongoing research and adoption of the ink into traditional electronics manufacturing. The ManTech program partnered with new powder and ink suppliers to effectively replace the lost supplier and meet the Army’s needs.
“There are several nanoparticle powder products being developed through this effort that are expected to improve density, hardness, conductivity and other performance factors across several applications. Some of the nanoparticle products may trade cost for better metrics but there is a strong focus on powder to performance for the Warfighter,” Canales said.