Tech Briefs

Low-Density, Creep Resistant Single Crystal Superalloys

Weights of aircraft turbine rotors could be reduced significantly. Several recently formulated nickelbase superalloys have been developed with excellent high-temperature creep resistance, at lower densities than those of currently used nickel-base superalloys. These alloys are the latest products of a continuing effort to develop alloys that have even greater strength-toweight ratios, suitable for use in turbine blades of aircraft engines. Mass densities of turbine blades exert a significant effect on the overall weight of aircraft. For a given aircraft, a reduction in the density of turbine blades enables design reductions in the weight of other parts throughout the turbine rotor, including the disk, hub, and shaft, as well as supporting structures in the engine. The resulting total reduction in weight can be 8 to 10 times that of the reduction in weight of the turbine blades.

Posted in: Materials, Briefs

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Aerogels for Thermal Insulation of Thermoelectric Devices

Energy-conversion efficiencies would be increased and operational lifetimes prolonged. Silica aerogels have been shown to be attractive for use as thermal insulation materials for thermoelectric devices. It is desirable to thermally insulate the legs of thermoelectric devices to suppress lateral heat leaks that degrade thermal efficiency. Aerogels offer not only high thermal insulation effectiveness, but also a combination of other properties that are especially advantageous in thermoelectric device applications.

Posted in: Materials, Briefs

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Nanotube Dispersions Made With Charged Surfactant

Dispersions (including monodispersions) of nanotubes in water at relatively high concentrations have been formulated as prototypes of reagents for use in making fibers, films, and membranes based on single-walled carbon nanotubes (SWNTs). Other than water, the ingredients of a dispersion of this type include one or more charged surfactant( s) and carbon nanotubes derived from the HiPco™ (or equivalent) process. Among reagents known to be made from HiPco™ (or equivalent) SWNTs, these are the most concentrated and are expected to be usable in processing of bulk structures and materials. Test data indicate that small bundles of SWNTs and single SWNTs at concentrations up to 1.1 weight percent have been present in water plus surfactant. This development is expected to contribute to the growth of an industry based on applied carbon nanotechnology. There are expected to be commercial applications in aerospace, avionics, sporting goods, automotive products, biotechnology, and medicine.

Posted in: Materials, Briefs

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Stability Enhancement of Polymeric Sensing Films Using Fillers

Enhanced stability of polymer sensing films is achieved by adding colloidal fillers. Experiments have shown the stability enhancement of polymeric sensing films on mixing the polymer with colloidal filler particles (submicron-sized) of carbon black, silver, titanium dioxide, and fumed silicon dioxide. The polymer films are candidates for potential use as sensing media in micro/nano chemical sensor devices. The need for stability enhancement of polymer sensing films arises because such films have been found to exhibit unpredictable changes in sensing activity over time, which could result in a possible failure of the sensor device.

Posted in: Materials, Briefs

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Active Struts With Variable Spring Stiffness and Damping

These struts would act as linear actuators and controllable shock absorbers.Controllable active struts that would function as linear actuators with variable spring stiffness and damping have been proposed as components of advanced suspension systems of future wheeled ground vehicles. The contemplated advanced suspension systems would include computer-based control subsystems that would continually adjust the actuator responses to obtain optimal combinations of safety and comfort under operating conditions ranging from low speeds over smooth roads to high speeds over rough, unpaved ground. The proposed struts and suspension systems were originally intended for use in military vehicles, but there could also be a broad commercial market for them in trucks and sport utility vehicles.

Posted in: Mechanical Components, Briefs

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Ultrasonically Actuated Tools for Abrading Rock Surfaces

These offer the same advantages as do ultrasonically actuated drilling and coring tools. An ultrasonic rock-abrasion tool (URAT) was developed using the same principle of ultrasonic/sonic actuation as that of the tools described in two prior NASA Tech Briefs articles: “Ultrasonic/Sonic Drill/Corers With Integrated Sensors (), Vol. 25, No. 1 (January 2001), page 38 and “Ultrasonic/Sonic Mechanisms for Drilling and Coring” (), Vol. 27, No. 9 (September 2003), page 65. Hence, like those tools, the URAT offers the same advantages of low power demand, mechanical simplicity, compactness, and ability to function with very small axial loading (very small contact force between tool and rock).

Posted in: Mechanical Components, Briefs

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Adding Hierarchical Objects to Relational Database General-Purpose XML-Based Information Managements

NETMARK is a flexible, high-throughput software system for managing, storing, and rapid searching of unstructured and semi-structured documents. NETMARK transforms such documents from their original highly complex, constantly changing, heterogeneous data formats into well structured, common data formats in using Hypertext Markup Language (HTML) and/or Extensible Markup Language (XML). The software implements an object-relational database system that combines the best practices of the relational model utilizing Structured Query Language (SQL) with those of the object oriented, semantic database model for creating complex data. In particular, NETMARK takes advantage of the Oracle 8i object-relational database model using physical-address data types for very efficient keyword searches of records across both context and content. NETMARK also supports multiple international standards such as WEBDAV for drag-and-drop file management and SOAP for integrated information management using Web services. The document-organization and -searching capabilities afforded by NETMARK are likely to make this software attractive for use in disciplines as diverse as science, auditing, and law enforcement.

Posted in: Software, Briefs

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