Materials

Thermal Conductivities of Some Polymers and Composites

Thermoset polymers are good electrical insulators that are used in applications ranging from electronics to composite armor. They are rather poor thermal conductors, however.

Posted in: Briefs, Aerospace, Defense, Electronic Components, Electronics, Electronics & Computers, Thermal Management, Composites, Materials, Instrumentation, Measuring Instruments, Test & Measurement
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Hybrid Ultra-Low VOC and Non-HAP Rain Erosion Coatings

Numerous military aircraft and shipboard surfaces, such as radomes, antennas, gun shields, wing leading edges, and helicopter blade leading edges, are coated with a specialized erosion-resistant protective coating possessing strict performance requirements. These protective coatings must provide excellent rain erosion resistance, superior mechanical properties, good adhesion to the substrate and meet a host of other metrics outlined in MIL-PRF-32239 and SAE AMS-C- 83231A.

Posted in: Briefs, Aerospace, Defense, Coatings & Adhesives, Mechanical Components
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Electrical Characterization of Crystalline UO2, THO2 and U0.71TH0.29O2

Tracking and identifying radiation sources in the age of nuclear proliferation and well- resourced non-state actors is a national priority. Current neutron detection methods favor large detector volumes and long data collection times. Additionally, portable neutron detection methods have persistent problems with low signal-to-noise (small pulse height) and require large applied voltages.

Posted in: Briefs, Aerospace, Defense, Materials, Mechanical Components, MEMs, Semiconductors & ICs, Data Acquisition, Detectors, Sensors
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Matrix-Free Assisted Laser Desorption Ionization Using Metal-Organic Frameworks

Matrix-assisted laser desorption/ionization (MALDI) is a soft ionization technique that is widely applied in the characterization of large biomolecules using various mass spectrometry (MS) analyzers, specifically, time-of-flight (TOF) analyzers. The MALDI process involves the deposition of an analyte solution onto a metal substrate before the addition of a matrix. The matrix/analyte dry spot is exposed to a UV laser, and the laser energy that is absorbed by the matrix/analyte is converted into heat energy that initiates charge transfer, which results in the desorption of the matrix and analyte molecules in ionized form. The positive ions are then accelerated through a vacuum into MS analyses.

Posted in: Briefs, Aerospace, Defense, Materials, Metals, Mechanical Components, MEMs, Data Acquisition, Sensors, Inspection Equipment, Instrumentation, Measuring Instruments, Monitoring, Test & Measurement
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Pulsed Microwave Plasma Instrumentation for Investigation of Plasma-Tuned Multiphase Combustion

Strategies to control solid rocket propellant regression rate require a robust throttling technique applicable to high performance propellant formulations. Currently, several methods to control and throttle either motors or subscale propellant strands exist, including chamber pressure control (e.g. pintle nozzles or rapid depressurization quench), infrared laser irradiation of the burning surface to increase burning rates, development of inherently unstable combustion chamber geometries (producing either local pressure or velocity perturbations), and electrically sensitive hydroxylammonium nitrate (HAN)-based formulations in which burning rate is controlled by a voltage potential. However, these techniques are limited in that they either can only be used with low flame temperature (low specific impulse) propellants, result in low propulsion system mass fraction (pintle), are only capable of producing a single perturbation, or are formulation specific.

Posted in: Briefs, Aerospace, Energy, Materials, Power Transmission, Propulsion, RF & Microwave Electronics, Instrumentation
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Microstructural and Mechanical Characterization of 2-D and 3-D SiC/SiNC Ceramic-Matrix Composites

The purpose of this endeavor was to investigate the effect of 3-D weave architecture on PIP-processed ceramic-matrix composites (CMC). Microstructural studies were performed to document the resulting microstructure and mechanical testing was performed to determine the high-temperature durability of the five different variants of SiC/SiNC CMC investigated.

Posted in: Briefs, Aerospace, Imaging, Ceramics, Composites, Materials, Mechanical Components
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Evaluation of Peel Ply Surface Preparation of Composite Surfaces for Secondary Bonding

Lightweight composite structures offer significant long-term cost-saving opportunities for the U.S. Army as replacements for traditional metal structures. However, high-strength economical bonding processes must be developed to join composites in order for them to be viable replacements. The Army is exploring approaches, also under evaluation in the commercial aerospace industry, to reduce the process steps associated with composite bonding.

Posted in: Briefs, Aerospace, Defense, Manufacturing & Prototyping, Ceramics, Materials, Metals, Joining & Assembly, Mechanical Components
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Enhanced Contacts for Inverted Metamorphic Multi-Junction Solar Cells Using Carbon Nanotube Metal Matrix Composites

In order to address issues related to mechanical and vibrational stresses that are commonly experienced in mounting, launch, and deployment of spacecraft, metal matrix composite (MMC) electrodes were fabricated with carbon nanotubes (CNTs) as reinforcement. The research plans were centered on first developing and selecting appropriate processes for fabricating CNT-MMCs based on characterization of their material properties, followed by optimizing MMC designs based on electrical testing under stress. Efforts in the program were also directed toward implementing the CNT-MMCs into solar cell device processing in a process compatible with standard clean room procedures.

Posted in: Briefs, Aerospace, Defense, Energy, Energy Efficiency, Energy Storage, Renewable Energy, Solar Power, Materials, Metals, Mechanical Components, Nanotechnology, Measuring Instruments, Test & Measurement
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Burner Rig Testing of A500® C/SiC

There is growing interest in developing, testing, and deploying ceramic-matrix composites (CMCs) into commercial and military aerospace gas turbine engines due to their durability under extreme conditions and weight-savings potential. For military applications, the focus is on the afterburning section of the turbine engine, including the flameholder, augmentor liner, and both the convergent and divergent segments of the exhaust nozzle. These are demanding applications because of the high temperatures and rapid thermal cycles.

Posted in: Briefs, Aerospace, Composites, Materials, Instrumentation, Measuring Instruments, Monitoring, Test & Measurement
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Space Debris Orbit and Attitude Prediction for Enhanced and Efficient Space Situational Awareness

This research deals with the problem of modelling the orbit and attitude motion of uncontrolled manmade objects in orbit about the Earth, which tumble due to the natural influences of the near-Earth space environment. A mathematical, physics-based and computational approach is taken to model the forces and torques that drive the orbit and attitude evolution of such objects. The main influence modelled is solar radiation pressure (SRP), which is the interaction of solar electromagnetic radiation with the surface of an object, leading to both forces and torques that influence the orbital and attitude motion. Other influences, such as the gravitational field of the Earth, are also modelled.

Posted in: Briefs, Aerospace, Imaging, Materials, Simulation Software, Transportation
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