Materials

Nanoparticle AlxMoyOz/Al Thermites

Research on the microstructures, chemical compositions, and reactivities of thermites that consist of or contain mixtures of MoO3 and Al particles has led to development of a process for making thermites that consist of or contain mixtures of AlxMoyOz and Al nanoparticles. The reactivities of the AlxMoyOz/Al thermites can be tailored through choices of ingredients at critical process steps. The findings of this and related research and development efforts may lead to the use of AlxMoyOz/Al thermites as components of insensitive weapon ignition systems.

Posted in: Briefs, Materials, Nanomaterials
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Metamaterials for Advanced Microwave Antennas

A report discusses a research and development project that has made contributions to the art of metamaterials for directing electromagnetic radiation at frequencies of the order of several gigahertz. The next-generation metamaterials expected to emerge from this and related projects could enormously improve the performances of microwave radar and communication antennas.

Posted in: Briefs, Materials, Antennas
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Accelerated Evaluation of Properties of Polyphase Alloys

A methodology for accelerated evaluation of mechanical properties of polyphase alloys is based on digital representations of the alloys. For a given alloy material system, this representation is utilized in concert with (1) software tools and probes that simulate traditional laboratory testing equipment and instrumentation, and (2) real laboratory mechanical testing by nontraditional methods.

Posted in: Briefs, Materials, Computer simulation, Alloys, Materials properties, Test equipment and instrumentation, Test procedures
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Plasma-Spray Coating as an Alternative to Chromium Plating

Plasma-spray application of coating materials that include tungsten carbide has been investigated as an alternative to electroplating of hard chromium onto internal metal surfaces that are required to be protected against wear or to be restored to within dimensional tolerances. Prime examples of such wear surfaces are the inner walls of cylinders in aircraft hydraulic actuators and dampers. The need for an alternative to chromium plating arises partly because chromium plating involves the use of hexavalent chromium, which is a highly toxic carcinogen subject to increasingly stringent government regulation and, therefore, increasingly expensive to use. Another reason for developing an alternative arises from a desire to reduce process time: To remove hydrogen that is unavoidably incorporated during chrome plating, it is necessary to perform a 24-hour bakeout. Process time could be reduced substantially if this bakeout could be eliminated. Plasma spraying involves fewer process steps than does electroplating, and for plasma-sprayed coatings, no hydrogen bakeout is necessary.

Posted in: Briefs, Materials, Spraying, Coatings Colorants and Finishes
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Measuring Glucose Using pH-Sensitive Hydrogels

Sensors that exploit pH-sensitive hydrogels for measuring concentrations of glucose in aqueous solutions are undergoing development. Because the underlying chemical and physical principles are also applicable to sensing of biochemicals other than glucose, it is expected to be relatively easy to modify the glucose sensors to enable detection of such biochemicals.

Posted in: Briefs, Materials, Sensors and actuators, Water, Biomaterials, Chemicals
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Composites Design and Structural Analysis Tool

AFRL researchers developed a unique design and structural analysis tool for composite materials, and they subsequently transitioned their product to manufacturers of helicopters and other rotorcraft. The new tool, the B-Spline Analysis Method (BSAM), makes it quicker and less expensive to characterize and predict the behavior of flaws or damage in the structures used to build these aircraft. AFRL developed the technology in coordination with the University of Dayton Research Institute (UDRI) and the United Technologies Research Center (UTRC) and then transitioned it to Sikorsky Aircraft Corporation.

Posted in: Briefs, Materials
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Corrosion Suppression Technologies and Techniques

Members of AFRL's Air Force Corrosion Prevention and Control Office (AFCPCO) teamed with corrosion experts from Warner Robins Air Logistics Center to assess environmentally induced damage to systems and equipment subjected to extended operations in Southwest Asia (SWA). The purpose of the ongoing assessment effort is to observe the effects of sand and dust intrusion on Air Force (AF) weapons systems and sensitive support equipment (see figure), analyze sands from various locations, and compare corrosion prevention and control policies and inspection requirements from prewar to present-day operations. As the investigation proceeds, team members are providing progressive and alternative approaches to corrosion prevention and control, wet and dry cleaning, and aircraft maintenance tasks performed in rigorous environmental conditions.

Posted in: Briefs, Materials
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Enhanced Blast-Resistant Windows

AFRL entered into a Cooperative Research and Development Agreement (CRADA) with Dlubak Technologies, Inc., of Freeport, Pennsylvania, to pursue ongoing research in blast-resistant window and glazing technologies. Dlubak Technologies—a 50-year-old glass manufacturing company—provided fullscale window and frame products (see Figure 1) to AFRL for blast mitigation testing at AFRL's Sky Ten Range, Tyndall Air Force Base, Florida.

Posted in: Briefs, Materials
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Friction Stir Welding of Aerospace Materials

AFRL scientists are studying a unique metal joining process— friction stir welding (FSW)—for building major structural assemblies. FSW is a solid-state welding process that forces a spinning tool along the joint line, heating the abutting components by friction and producing a weld joint formed by strong plastic mixing (stirring) of the two components' constituent materials. FSW promises to be a highly efficient and cost- effective alternative to the conventional fusion welding routinely used for joining structural alloys on military and civilian aircraft.

Posted in: Briefs, Materials
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Integrated Aircraft Oxygen Sensor

Shortly after its takeoff from New York City on July 17, 1996, Trans World Airlines (TWA) Flight 800 exploded over the Atlantic Ocean and crashed. The accident investigation board determined that the center wing fuel tank caught fire and exploded. Although the ignition source remains unknown, it was unquestionably the presence of a combustible fuel/air mixture in the center wing fuel tank that caused the resulting

explosion.

Posted in: Briefs, Materials
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