Newsletters: 2007, Issue 1

Advanced Materials Research and Development at PSI

In its early decades, Physical Sciences Inc. contributed to solving problems related to ballistic missile atmospheric re-entry, decoy discrimination, defense against emerging high power lasers, design of high temperature fuel cells and advanced coal combustion systems. All of these research programs required some knowledge of the behavior of complex materials in harsh environments.

Today, PSI not only exploits the latest developments in the material sciences; we are actively involved in the creation of new materials for hypersonic vehicles, electronic and electro-optical devices, ultra-strong structures, and advanced power sources. The development of new manufacturing processes to enable cost-effective production is a critical aspect of these projects. In this issue, we highlight just a few of these exciting activities.

High Temperature Materials

Fred Lauten

PSI has developed high temperature inorganic materials as cost effective products with significantly increased performance over the state-of-the-art for defense, energy and commercial applications. Led by Dr. Fred Lauten, the Advanced Composite Structures Group at PSI is successfully developing and manufacturing durable structural components that operate at temperatures ranging from cryogenic to 4950^oF in highly corrosive environments. Current infrastructure enables the design and production of complex shape ceramic and polymer matrix components. Our cross-disciplinary team of chemists, physicists, materials scientists and mechanical engineers also develop embedded health monitoring sensors, rapid laser machining tools, and structural insulating materials.

HyFly Booster Test Vehicle

PSI is currently working on a number of programs to develop ceramic matrix composite (CMC) flight components for aerospace systems. In these programs, we are fabricating complex components that maintain tight dimensional tolerances. We have demonstrated CMC components with thermo-mechanical and thermo-chemical stability to over 4950^oF. We have also demonstrated the ability to cost-effectively fabricate and machine more than 500 CMC components and test articles, and have established a Six Sigma-based Manufacturing Development Plan. These efforts have enabled us to transition into the DARPA/ONR HyFly Missile Demonstrator program. PSI has produced the first sets of flight articles, including the combustor nozzle assembly, which contain a number of high tolerance attamchent features. These components operate at temperatures of over 4000^oF for the flight duration.

PSI is also performing an MDA-funded Phase II SBIR program to develop complex shape, high tolerance components for existing and advanced Throttled Divert and Attitude Controls Systems (TDACS). We have successfully fabricated CMC propellant dome cap liners with multiple inlet and outlet channels while maintaining complex curvatures. Currently, we have produced these components for ground test qualification in 2007, and are beginning to manufacture articles for flight qualification and insertion into fielded missile defense systems such as the Standard Missile. We have also manufactured CMC nozzle inlets, nozzle plenums and thrust chambers for future systems.

Throttled Divert and Attitude Control System (TDACS)

PSI's 4000 square foot composites process facilities include several furnaces operating at temperatures up to 1750^oC. This pilot scale manufacturing facility has fiber pre-forming, process, and furnace capabilities that enable on-site fabrication of ceramic composites. In addition, on-site PSI analytical resources include Field Emission SEM, FTIR, UV-VIS, spectrometer and viscometer, as well as mechanical testing, analytical chemistry, and polymer synthesis facilities.

Carbon Nanotubes for Synthetic Multifunctional Materials

Multifunctional Carbon NanoTube (CNT) materials have attracted great interest for a wide range of applications from loadbearing structures to nano-electronics sensing and energy storage. This is due to their combination of superior physical and electronic properties. Several research groups are focusing on the development of controlled, high volume manufacturing of CNT's. This will form the basis for revolutionary new multifunctional materials.

200,000X TEM Image of PSI Electrospun Carbon Fibers (the tube marked is about 15 nm in diameter)

John Lennhoff

John Lennhoff, Manager of Materials Technologies of PSI, is evaluating nanometer-diameter carbon fibers that are thermodynamically favored to form single wall and multi-wall carbon nanotubes (MWNTs). This approach offers the potential for high volume, low cost carbon nano-tube production. Electrospinning is used to produce nanometer-diameter polymer precursor fibers, which are then pyrolyzed to form CNTs. PSI has recently demonstrated MWNT synthesis starting from a 15 nanometer polyacrylonitrile fiber precursor.

Electroactive Polymer for Controlling Overcharge in Lithium-Ion Batteries

Lithium-ion cells need to be charged to a specified cutoff voltage in order to maintain safe operation and to achieve high cycle and calendar life. Generally, lithium-ion cells are used in battery packs with cells in series for appliances such as laptop computers and hybrid electric vehicles. Cell-to-cell capacity variations result in overcharging of the low capacity cells that cause reduced battery life.

Controlling overcharge with either a reversible oxidation-reduction (Redox) reaction at each electrode or a blended electroactive polymer separator have had limited success due to voltage and current density constraints. Redox shuttle molecules decompose at the charging voltages of commercial lithium-ion cells and cannot carry sufficient current. Electroactive polymer blends also have voltage and current density limitations. These shortcomings are due to the low oxidation potential and low loading of the electroactive polymer possible in an industry standard separator.

Aron Newman

Dr. Aron Newman, Principal Scientist, has developed a nanoporous separator that contains electroactive polymers as an integral component rather than as an additive to an existing separator material. This separator switches from an insulator to a conductor upon overcharging. This technology provides higher overcharge current density shunting and enables operation within the voltage constraints of lithium ion cells while preventing cell corrosion.

Contract News

PSI recently received several government contracts, including: "Bayesian Reasoning for Improved Standoff Detection of Chemical and Biological Warfare Agents" from the Defense Threat Reduction Agency; "First Article Testing of In-Line Fuel Monitoring System (Autogrape)" from the Naval Surface Warfare Center; and "Rapid Development of DNA Aptamers for Agent Identification, Tracking and Neutralization" from the Air Force Materiel Command.

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Physical Sciences Inc.
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