Gamma-ray shielding performance of carbon nanotube film material

This paper aims to explore the shielding potential of light-weight carbon nanotube (CNT) film materials against gamma-ray generated from americium-241 (241Am) and caesium-137 (137Cs). The influence factors of gamma mass attenuation coefficient of CNT film laminates were investigated to reveal structure-property relationship. The results showed that CNT film materials had bigger mass attenuation coefficients than carbon fiber reinforced composites, suggesting stronger radiation interaction induced by CNT’s cylindrical nanostructure. CNT alignment was proved to be conducive to the improvement of mass attenuation coefficient and gamma attenuation ratio. Aligned CNT film laminate with the thickness of 10 mm had a mass attenuation coefficient of 0.086 cm2 /g and attenuation ratio of 4.9% against gamma-ray exposed to 137Cs, which were higher than those of aluminum, iron or copper sheets. CNT film material demonstrated its potential for the application of light-weight gamma-ray safety equipment and devices.

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DexMat Awarded Phase I SBIR: Lightweight CNT Shielded Cables for Space Applications

Abstract: The effects of electromagnetic interactions in electrical systems are of growing concern due to the increasing susceptibility of system components to electromagnetic interference (EMI), use of automated electronic systems, and pollution of the electromagnetic environment (EME) with electromagnetic emissions. The effects of EMI can be detrimental to electronic systems utilized in space missions; even small EMI issues can lead to total mission failure, resulting in significant mission delays and economic loss. Additionally, NASA is challenged to find ways of effectively shielding sensitive electronic equipment from EMI without adding significant weight to space flight vehicles and satellites in order to manage fuel costs. The solution for both issues resides in the use of carbon nanotubes (CNTs), which are advancing as the most promising solution for reducing the weight of spacecraft wires. CNTs are an alluring alternative to conventional conductors used in coaxial data cables because they combine mechanical strength, electrical conductivity, and low density. DexMat has developed a novel CNT deposition process for directly applying CNTs onto dielectric materials to produce an electrically conductive EMI shield. The high conductivity CNT fibers have the potential to replace the inner conductor in cables, improving their mechanical durability and providing comparable specific conductivity to copper. By placing a premium on the quality of raw CNTs, DexMat has created a product which will have increased potential to reduce cable weight while minimizing insertion losses when incorporated into wire. In the proposed research DexMat seeks to increase electrical conductivity of CNT films, produce cost competitive products, develop new quality assurance processes, and determine the long-term product reliability of CNT cables. Understanding these facets of CNT cable production will lead to enhancements on DexMat innovation and production of a commercially viable product.

Project Details: https://www.sbir.gov/sbirsearch/detail/1217639

DexMat Awarded Phase I SBIR: High Conductivity CNT Wiring for High Speed Data Cables

Abstract: In an era of reduced Defense budgets and increasing threats, military planners are seeking new technologies to reduce operating costs and increase operation capabilities for space and aviation platforms, and weight reduction is an attractive target. For example, transportation costs to geosynchronous orbits using a NASA reusable launch vehicle are close to $10,000 per pound of payload. Copper wiring, which makes up as much as one-third of the weight of a 15-ton satellite and 20 miles of an F-22 aircraft, is a clear target for weight reduction. Half of this wire weight is typically in the EMI shielding. Developing new lightweight, conductive materials that replace copper in the shielding and core conductor could serve as a lead candidate for radically reducing this weight. Carbon nanotubes (CNTs) combine high strength, electrical and thermal conductivity with low density, which makes them ideal for applications where weight reduction is a priority. DexMat is commercializing CNT technology that has shown the highest published values for conductivity and mechanical strength of CNT materials. This Phase I Proposal will examine the feasibility of developing CNT-based cables with solution-processing technology capable of producing high performance CNT fibers and coatings, without the use of binders and wetting agents.BENEFIT:The potential benefits of this innovation could include military development for future ground, air or space systems that have stringent weight requirements, including launch vehicles, UAVs, portable communications,small satellites,etc. Commercial Application: Any commercial development for electronic-heavy systems with stringent weight requirements, including jetliners, satellites, small computers, etc.

Project Details: https://www.sbir.gov/sbirsearch/detail/824749