A team of engineering faculty members received a $1.47 million subcontract from defense giant Raytheon Company to assist in the development of engineered nanocomposites for optical applications. The project is being funded by the Defense Advanced Research Projects Agency (DARPA) and managed by the Office of Naval Research (ONR).
The project team includes principal investigator Eric Jordan, professor of Mechanical Engineering (ME), and deputy manager Maurice Gell, a research scientist affiliated with the Chemical, Materials & Biomolecular Engineering department (CMBE). Critical tasks will be overseen by Baki Cetegen, professor and department Head of ME, and Mark Aindow, professor of CMBE. Partnering with the UConn-led, multi-institutional team are Inframat Corporation of Farmington, CT and researchers from MIT and the University of Michigan. Raytheon has subcontracted other portions of its larger DARPA contract to Rutgers University and the University of California – Davis.
The UConn team will seek to develop a new ceramic material that has the necessary optical properties as well as excellent mechanical and physical properties. These requirements greatly limit the choice of potential materials systems, according to Dr. Jordan. “To achieve optical transparency, it is necessary for the material to be fully dense and free of light-scattering defects such as micro-pores and cracks. Accordingly, the materials to be made are at or beyond the cutting edge of ceramics processing,” said Dr. Jordan.
The UConn team was chosen for the project in large measure because of a unique new ceramic processing method it pioneered in partnership with Inframat Corporation. In this process, called Solution Precursor Plasma Spray (SPPS), chemical precursor droplets are injected into a plasma jet to form the ceramic in its brief flight to the substrate. The SPPS process offers significant advantages that are favorable for the DARPA project. It involves molecular-level mixing of multi-component ceramic materials, the ability to control chemical purity, and the flexibility to rapidly explore new compositions.
A project goal is to achieve transparency in the infrared optical range. To do so, the team must produce a nano-grained material that is stable at elevated temperatures. Dr. Jordan explained that thanks to its high cooling rates, the SPPS process commonly produces oxide ceramic microstructures with grain/crystal sizes of less than 100 nanometers. A nanometer is 10-9 meters, a size so minute that it would take 80,000 nanometers to equal the width of a human hair. The SPPS process can effectively produce multi-component microstructures at the nanometer scale, called nanocomposites, that are high-strength as well as resistant to erosion and thermal shock. For this first phase of the DARPA contract, the UConn-led team will screen potential optical materials and optimize the SPPS process.
“To guide the experimentation, considerable effort will be devoted to gaining an understanding of – and modeling – the materials and processing characteristics, including the study of the behavior of droplets in the high-temperature, high-velocity plasma jet,” said Dr. Jordan. The modeling of useful optical properties is also important and will be carried out by Raytheon and locally in an effort led by Dr. Paul Klemens, professor emeritus of physics.
Dr. Jordan commented that the project’s greatest challenge is to fabricate defect-free, bulk ceramics, a task that will require innovative approaches and an advancement of the ceramic processing state of the art.