materials and coatings
Carbon Fiber-Carbon Nanotube Yarn Hybrid Reinforcement
NASA's new material is a toughened triaxial braid made from ductile carbon nanotube (CNT) yarn hybridized with carbon fiber, which is ultimately used as reinforcement material to make toughened polymer matrix composites. The CNT yarn component of the reinforcement is solely responsible for adding toughness, while the processes used to optimize the fiber braiding parameters and tensile properties of the carbon fiber-CNT yarn hybrid tow material determine the overall improvement in tensile strength for resin impregnated fiber tows. Bundles of continuous carbon nanotube yarns are combined with a similar format of carbon fiber, yielding an easily scalable process. Advantages of the material include reduced cost by eliminating use of toughening agents, increased ability to conform to highly complex geometries, greater environmental stability compared to aramid fiber reinforcements such as Kevlar, and possibly decreased density. Many hybrid reinforcements exhibit interfacial compatibility issues, which could lead to premature failure via crack propagation at the polymer matrix interface. In contrast, chemical similarities between the CNT yarn and carbon fiber constituents impart NASA's hybrid reinforcement material with excellent interfacial compatibility. Potential applications include aerospace components, composite pressure vessels, wind turbine blades, automotive components, prosthetics, sporting equipment, construction reinforcement material, and other use-cases where strength-to-weight ratio is of utmost importance.
Solid State Carbon Dioxide (CO<sub>2</sub>) Sensor
The technology is a solid state, Carbon Dioxide (CO<sub>2</sub>) sensor configured for sensitive detection of CO<sub>2</sub> having a concentration within the range of about 100 Parts per Million (ppm) and 10,000 ppm in both dry conditions and high humidity conditions (e.g., > 80% relative humidity). The solid state CO<sub>2</sub> sensor achieves detection of high concentrations of CO<sub>2</sub> without saturation and in both dynamic flow mode and static diffusion mode conditions. The composite sensing material comprises Oxidized Multi-Walled Carbon Nanotubes (O-MWCNT) and a metal oxide, for example O-MWCNT and iron oxide (Fe2O3) nanoparticles. The composite sensing material has an inherent resistance and corresponding conductivity that is chemically modulated as the level of CO<sub>2</sub> increases. The CO<sub>2</sub> gas molecules absorbed into the carbon nanotube composites cause charge-transfer and changes in the conductive pathway such that the conductivity of the composite sensing material is changed. This change in conductivity provides a sensor response for the CO<sub>2</sub> detection. The solid state CO<sub>2</sub> sensor is well suited for automated manufacturing using robotics and software controlled operations. The solid state CO<sub>2</sub> sensor does not utilize consumable components or materials and does not require calibration as often as conventional CO<sub>2</sub> sensors. Since the technology can be easily integrated into existing programmable electronic systems or hardware systems, the calibration of the CO<sub>2</sub> sensor can be automated.