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Velcro customization - Rice University and NASA collaborate to develop silicon carbide "fuzzy fiber" like "Velcro"
- 2018-11-07-

Rice University collaborated with NASA to develop a "magic patch" (a velcro, also known as a Velcro tape or a buckle, which is a commonly used connection accessory on clothes, which can be customized according to different needs). Silicon carbide "fuzzy fiber", which can withstand the test of materials in the aerospace field, its heat resistance and oxidation resistance are outstanding. This electron microscope image shows how the silicon carbide nanotubes attached to the separated silicon carbide fibers are entangled with each other.

Rice University and NASA collaborate to develop silicon carbide "fuzzy fiber"

In a paper in Applied Materials and Interfaces, the researchers report that the fiber can be used in composite materials for advanced rocket engines that can withstand temperatures up to 1600 ° C (2912 ° F).

Ceramic composites in rockets currently under development use silicon carbide fibers to reinforce materials, but they rupture or become brittle when exposed to oxygen. Rice Labs embeds silicon carbide nanotubes and nanowires on the surface of NASA fibers. Nanotubes and nanowires are curled, like hooks and loops, which make "magic" very valuable - but only on the nanometer scale. According to Amelia Hart, a lead researcher and a postdoctoral researcher, Chandra Sekhar Tiwary, they have very strong interlocking connections at the fiber entanglement. This not only makes the composite less prone to cracking, but also seals it to prevent oxygen from changing the chemical composition of the fiber. When Hart (she has been studying the growth of carbon nanotubes on ceramic wool fabrics) met MichaelMeador (he is NASA's scientist at the Glenn Research Center in Cleveland), at the opening ceremony of Les Materials Science and Nano Engineering. The study was started. (Meador is now the nanotechnology project manager for NASA's Game Transformation Technology project.) This gives Hart the opportunity to share her ideas with NASA research engineer and paper collaborator Janet Hurst. Hart said: "She is transforming silicon carbide from carbon nanotubes," she said. "We use her formula and my ability to grow nanotubes and figure out how to make new composites." Hart and Her colleagues developed hooks and loops by first soaking silicon carbide fibers in an iron catalyst and then using water-assisted chemical vapor deposition. This process was developed in part by Rice, which directly embeds a layer of carbon nanotubes on the fiber surface. . The fibers are then heated in a silicon nanopowder at a high temperature to convert the carbon nanotubes into silicon carbide "fluff". Researchers hope that their "fuzzy fibers" can be upgraded into high-strength, lightweight and heat-resistant silicon carbide fibers that have been added to ceramic composites to test for robust nozzles and other components in rocket engines. Tiwary said: "Because the silicon carbide fibers they are using are very stable at 1600 ° C, we believe that the enhancement by attaching silicon carbide nanotubes and nanowires will make it more sophisticated." New materials can also make the entire turbine The engine is significantly lightened. Hart said: "Before they used SiC composites, many of the engine components were made of nickel superalloys. These nickel alloys must be combined with a cooling system, which increases the weight of the entire system." "Using ceramic matrix composites Materials, they can omit the cooling system and can be used at higher temperatures."

Our materials will allow the manufacture of larger and longer-lasting turbojets than ever before. Friction and compression tests have shown that the lateral force required to move silicon carbide nanotubes and nanowires to each other greatly exceeds the force required to slide over planar nanotubes or without the addition of reinforcing fibers.

The fuzzy fibers can also be easily restored under the enormous pressure exerted by the nano-indenter, indicating that they are capable of resisting long-term loads. Heat treatment tests of the fibers have shown that silicon carbide nanotubes are easily resistant to temperatures up to 1000 ° C when ordinary carbon nanotubes are burned from the fibers.

Hart said the next step is to apply its conversion technology to other carbon nanomaterials to create unique three-dimensional materials for other applications.