Sensory Metallic Materials
While almost all advancements in nondestructive evaluation (NDE) focus on improving the NDE equipment and techniques, any testing is inherently limited by the response of the materials being tested. This technology seeks to improve the response of the material itself by embedding shape memory alloy (SMA) particles in the metallic structural alloy in a manner that does not compromise the structural integrity of the material. These SMA particles undergo a martensitic phase change (crystallographic change) in response to strain (e.g., a crack tip causing local deformation). The phase change produces an acoustic emission and a change in magnetic properties that can easily be detected and monitored, providing a means for enhanced NDE. The advantage is either that (1) the technology makes available existing NDE techniques that were not applicable before because of the type of structural material being used (the particles add new physics to the base structure) or (2) the technology enhances NDE because the SMA particles create conditions that are easier to detect damage relative to the equivalent level of damage in a structure without particles.
materials and coatings
High Precision Metal Thin Film Liftoff Technique
The purpose of this innovation is to pattern thin metal films on a silicon substrates. These thin metal films can be deposited using physical vapor deposition techniques, which include thermal evaporation, electron-beam evaporation, and DC magnetron sputtering. The steps involved to realize this innovation include fabricating the liftoff mask, depositing the metal, and lifting off the metal in acetone. Fabrication of the liftoff mask consists of spinning on the polymer layer, depositing the germanium layer, patterning the germanium layer using a polymeric photoresist, etching the germanium layer using a reactive ion etcher (RIE), and etching the polymer layer using an oxygen plasma. Alternate embodiments of this innovation involve using different polymer layer materials and different germanium thicknesses. This innovation requires the use of standard photolithographic equipment, which includes a spin coater, a hotplate, and a mask aligner. It also requires the use of a reactive ion etcher (RIE) to etch the germanium and ash the polymer layers. The novel features of this innovation are the high degree of control over the thicknesses of each liftoff mask layer and the amount of undercut in the polymer layer. The undercut is precisely and reproducibly controlled inside the RIE by setting the amount of oxygen gas flow, power, and ash time.
mechanical and fluid systems
Nitinol-Actuated Normally Open Valve Assembly (NOVA)
The nitinol-actuated Normally Open Valve Assembly (NOVA) is a type of zero-leak permanent isolation valve designed for liquid propellant service on in-space propulsion systems with operating pressures less than or equal to 500 psia. The NOVA is a drop-in replacement for the currently used pyrovalve. Prior to actuation, the valve allows propellant flow with a pressure drop of < 3 psi at a flow rate of 0.15 kg/s. A compressed piece of nitinol inside the valve is heated once actuation is desired, causing the nitinol to recover to its origin shape. This recovery closes the valve, creating a leak-tight seal. The valve is compatible with all storable propellants.
materials and coatings
Functionally Graded Metal-Metal Composite Structures
In order to improve the properties of monolithic metallic materials, alloying additions are made that create secondary phases and/or precipitate structures. These improvements must occur during melt solidification and are governed by the thermodynamics of the process. That is, optimizing the metallic alloy is possible only as much as thermodynamics allow. Developing novel methods to combine metallic compositions/alloys into a fully dense material is of interest to create materials with novel property combinations not available with monolithic alloys.While various approaches for layering two-dimensional materials exist, their capabilities are typically limited and non-isotropic. Further, while three-dimensional composites may be formed with conventional powder metallurgy processes, it is generally very difficult to control the arrangement of the phases, for example due to randomness created by mixing powders. This invention is method for creating a multiple alloy composite structures by forming a three-dimensional arrangement of a first alloy composition, in which the three-dimensional arrangement has a substantially open and continuous porosity. The three-dimensional arrangement of the first alloy composition is infused with at least a second alloy composition. The three-dimensional arrangement is then consolidated into a fully dense solid structure.
materials and coatings
How to Train Shape Memory Alloys
Glenn researchers have optimized how shape memory alloys (SMAs) are trained by reconceptualizing the entire stabilization process. Whereas prior techniques stabilize SMAs during thermal cycling, under conditions of fixed stress (known as the isobaric response), what Glenn's innovators have done instead is to use mechanical cycling under conditions of fixed temperature (the isothermal response) to achieve stabilization rapidly and efficiently. This novel method uses the isobaric response to establish the stabilization point under conditions identical to those that will be used during service. Once the stabilization point is known, a set of isothermal mechanical cycling experiments is then performed using different levels of applied stress. Each of these mechanical cycling experiments is left to run until the strain response has stabilized. When the stress levels required to achieve stabilization under isothermal conditions are known, they can be used to train the material in a fraction of the time that would be required to train the material using only thermal cycling. As the strain state has been achieved isothermally, the material can be switched back under isobaric conditions, and will remain stabilized during service. In short, Glenn's method of training can be completed in a matter of minutes rather than in days or even weeks, and so SMAs become much more practical to use in a wide range of applications.
materials and coatings
High-Performance Polyimide Powder Coatings
Powder coatings are used throughout industry to coat a myriad of metallic objects. This method of coating has gained popularity because it conserves materials and eliminates volatile organic compounds. Resins traditionally chosen for powder coatings have low melting points that enable them to melt and flow into a smooth coating before being cured to a durable surface. High-performance resins, such as Teflon, nylon, and polyimide, have not been found suitable for use in powder coatings because of their high melting points. However, KSC's newly developed polyamic acid resins with low melting points can be used in a powder coating. These polyamic acid resins, when sprayed onto metal surfaces, can be cured in conventional powder coating ovens to deliver high-performance polyimide powder coatings. The polyimide powder coatings offer superior heat and electrical stability as well as superior chemical resistance over other types of powder coatings.
NASA-427: A New Aluminum Alloy
The NASA-427 alloy, with its origins in the Ares rocket program, has high potential for use in a number of automotive applications, including cast aluminum wheels, control arms, steering knuckles, and other components. Why its Better This technology uses precise chemistry to improve the mechanical properties of cast aluminum products, which demonstrate substantial increases in impact toughness due to the improvement in tensile strength and ductility. The steps necessary to complete the thermal coating process proceed more quickly using this new alloy the heat treatment process is much shorter, and the aging process has been optimized in conjunction with the powder or paint-baked coating process. It also offers improved corrosion resistance meeting or exceeding the performance of A356-T6 alloy, as well as offering significant cost-savings over forging 6016-T6 alloy when elongation is less than seven percent. Because of its superior tensile strength coupled with significant process improvements, choosing NASA- 427 yields energy and cost savings for both the manufacturer of cast aluminum components and the end-user.
mechanical and fluid systems
High-Temperature Single Crystal Preloader
For extremely high-temperature sealing applications, Glenn researchers have devised novel methods for fabricating single-crystal preloaders. NASA's high-temperature preloaders consist of investment cast or machined parts that are fabricated in various configurations from single crystal superalloys. Machined preloaders include a variety of spring configurations, compressed axially or radially, fabricated from single crystal slabs. Before machining, the slabs are carefully oriented in a special goniometer using x-diffraction techniques. This helps to maintain proper crystal orientation relative to the machined part and the applied loads. For more complex geometry components which cannot be easily and economically machined, an investment casting approach would be used. Complex preloader geometries include wire coil springs of various configurations. These single crystal preloaders would be designed with the appropriate stiffness for the intended thermal barrier/seal application and placed underneath, or integrated within, the seal/barrier. At extrememly high temperature, the preload device keeps the seal/barrier mated against the opposing surface as the gap between the two surfaces changes, maintaining contact between surfaces and preventing convective heat transfer.
electrical and electronics
Metal Oxide-Vertical Graphene Hybrid Supercapacitors
The electrodes are soaked in electrolyte, separated by a separator membrane and packaged into a cell assembly to form an electrochemical double layer supercapacitor. Its capacitance can be enhanced by a redox capacitance contribution through additional metal oxide to the porous structure of vertical graphene or coating the vertical graphene with an electrically conducting polymer. Vertical graphene offers high surface area and porosity and does not necessarily have to be grown in a single layer and can consist of two to ten layers. A variety of collector metals can be used, such as silicon, nickel, titanium, copper, germanium, tungsten, tantalum, molybdenum, & stainless steel. Supercapacitors are superior to batteries in that they can provide high power density (in units of kw/kg) and the ability to charge and discharge in a matter of seconds. Aside from its excellent power density, a supercapacitor also has a longer life cycle and can undergo many more charging sequences in its lifespan than batteries. This long life cycle means that supercapacitors last for longer periods of times, which alleviates environmental concerns associated with the disposal of batteries.
materials and coatings
Sequential/Simultaneous Multi-Metalized Nanocomposites (S2M2N)
Well-dispersed metal decorated nanotube or nanowire polymer composites have rarely been reported because of the excessive weight contrast between the decorated tubes and the polymer matrix. However, various properties, such as high electrical conductivity, permittivity, permeability, wear resistance, anti-penetrant, radiation shielding and high toughness are desirable and can be achieved with SeM2N metalized nanocomposites. Further, it is desirable to have nanocomposites that exhibit improvement in more than one of these properties and thus be capable of performing multiple functions. This invention provides a method to decorate pre-resided nanotube (CNT, BNNT, GPs) or nanowire surfaces in a polymer matrix with metal nanoparticles via supercritical fluid (SCF) deposition.