Materials

A Model of Reduced Oxidation Kinetics Using Constituents and Species

The advantage of such a simple model becomes increasingly significant with increasing carbon atoms of the fuel. NASA’s Jet Propulsion Laboratory, Pasadena, California Elementary-reaction chemical kinetics of hydrocarbon oxidation consists of hundreds to thousands of species and thousands of reactions. As such, it is impossible to use it in models and codes involving turbulence because computations are unfeasible due to lack of memory and computer speed. The solution is to reduce the elementary chemical kinetics to a much smaller set of representative reactions. A kinetic reduction has been shown to work very well for isooctane and its mixtures with n-pentane, iso-hexane, and n-heptane.

Posted in: Materials, Software, Briefs

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Determining Radiation Shielding Capability of the Earth’s Atmosphere from FAA Radiation Data

An algorithm is used to determine how much material is needed to shield astronauts on their trip to Mars. John F. Kennedy Space Center, Florida The FAA, using its CARI-6 program, provides galactic cosmic radiation dosage rates for any location on the Earth from ground up to 60,000 ft (≈18,300 m). One way to protect astronauts from galactic cosmic radiation (GCR) on a Mars mission is to use material shielding. However, current radiation shielding code does not model shields thicker than about 100 to 200 gm/cm2, and it has been shown that this shield thickness is insufficient to provide protection for a trip to Mars. There is effort underway to extend the code to thicker shields, but there is a lack of experimental data to use to verify the code. The atmosphere represents a very thick and effective radiation shield, and that atmospheric radiation data might be used as a source of verification data.

Posted in: Materials, Software, Briefs

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Water Splitter Runs on AAA Battery

Scientists at Stanford University have developed a low-cost, emissions-free device that uses an ordinary AAA battery to produce hydrogen by water electrolysis.  The battery sends an electric current through two electrodes that split liquid water into hydrogen and oxygen gas. Unlike other water splitters that use precious-metal catalysts, the electrodes in the Stanford device are made of inexpensive and abundant nickel and iron.In addition to producing hydrogen, the novel water splitter could be used to make chlorine gas and sodium hydroxide, an important industrial chemical. Splitting water to make hydrogen requires no fossil fuels and emits no greenhouse gases. But scientists have yet to develop an affordable, active water splitter with catalysts capable of working at industrial scales."It's been a constant pursuit for decades to make low-cost electrocatalysts with high activity and long durability," said Stanford University Professor Hongjie Dai. "When we found out that a nickel-based catalyst is as effective as platinum, it came as a complete surprise."SourceAlso: Learn about a Proton Exchange Membrane Fuel Cell.

Posted in: Batteries, Electronics & Computers, Power Management, Alternative Fuels, Green Design & Manufacturing, Materials, Metals, Energy, News

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Researchers Create Energy-Absorbing Material

Materials like solid gels and porous foams are used for padding and cushioning, but each has its own advantages and limitations.A team of engineers and scientists at Lawrence Livermore National Laboratory (LLNL) has found a way to design and fabricate, at the microscale, new cushioning materials with a broad range of programmable properties and behaviors that exceed the limitations of the material's composition, through additive manufacturing, also known as 3D printing. Livermore researchers, led by engineer Eric Duoss and scientist Tom Wilson, focused on creating a micro-architected cushion using a silicone-based ink that cures to form a rubber-like material after printing. During the printing process, the ink is deposited as a series of horizontally aligned filaments (which can be fine as a human hair) in a single layer. The second layer of filaments is then placed in the vertical direction. This process repeats itself until the desired height and pore structure is reached.The researchers envision using their novel energy-absorbing materials in many applications, including shoe and helmet inserts, protective materials for sensitive instrumentation, and in aerospace applications to combat the effects of temperature fluctuations and vibration.SourceAlso: Read more Materials tech briefs.

Posted in: Manufacturing & Prototyping, Rapid Prototyping & Tooling, Materials, Aerospace, Defense, News

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NASA 3D Printing Technique Creates Metal Spacecraft Parts

Researchers at NASA's Jet Propulsion Laboratory are implementing a printing process that transitions from one metal or alloy to another in a single object. JPL scientists have been developing a technique to address this problem since 2010. An effort to improve the methods of combining parts made of different materials in NASA's Mars Science Laboratory mission inspired a project to 3D print components with multiple alloy compositions.

Posted in: Manufacturing & Prototyping, Rapid Prototyping & Tooling, Materials, Metals, Aerospace, News

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Secret of Eumelanin’s Ability to Absorb Broad Spectrum of Light Uncovered

Melanin — and specifically, the form called eumelanin — is the primary pigment that gives humans the coloring of their skin, hair, and eyes. It protects the body from the hazards of ultraviolet and other radiation that can damage cells and lead to skin cancer. But the exact reason why the compound is so effective at blocking such a broad spectrum of sunlight has remained something of a mystery. Now, however, researchers at MIT and other institutions have solved that mystery, potentially opening the way for the development of synthetic materials that could have similar light-blocking properties.

Posted in: Electronics & Computers, Photonics, Optics, Materials, Composites, Medical, Solar Power, Energy, News

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Engineers Hope to Create Electronics That Stretch at the Molecular Level

Nanoengineers at the University of California, San Diego are asking what might be possible if semiconductor materials were flexible and stretchable without sacrificing electronic function?

Posted in: Electronics & Computers, Electronic Components, Board-Level Electronics, Electronics, Materials, Sensors, Semiconductors & ICs, News

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