If the composite fibres used to make next-generation rocket engines are fuzzy they can stand the heat and pressure. Therefore, The Rice University laboratory of materials scientist Pulickel Ajayan, in collaboration with NASA, has developed “fuzzy fibers” of silicon carbide that act like Velcro and resist the harsh environment that materials experience in aerospace applications.
The Rice lab embedded silicon carbide nanotubes and nanowires into the surface of NASA’s fibers. The exposed parts of the fibers are curly and act like the hooks and loops like Velcro, on the nanoscale. This creates very strong interlocking connections where the fibers tangle. It makes the composite less prone to cracking and seals it to prevent oxygen from changing the fiber’s chemical composition.
The researchers grew their hooks and loops by first bathing silicon carbide fiber in an iron catalyst and then using water-assisted chemical vapor deposition, a process developed in part at Rice, to embed a carpet of carbon nanotubes directly into the surface. These become the template for the final product. The fibers were then heated in silicon nanopowder at high temperature, which converts the carbon nanotubes to silicon carbide “fuzz.”
The researchers hope their fuzzy fibers will upgrade the strong, light and heat-resistant silicon carbide fibers that, when put in ceramic composites, are being tested for robust nozzles and other parts in rocket engines.
Friction and compression testing showed the lateral force needed to move silicon carbide nanotubes and wires over each other was much greater than that needed to slide past either plain nanotubes or unenhanced fibers, the researchers reported. They were also able to easily bounce back from high compression applied with a nano-indenter, which showed their ability to resist breaking down for longer amounts of time.Tests to see how well the fibers handled heat showed that the silicon carbide nanotubes easily resisted temperatures of up to 1,0000C.
According to the researchers, the next step is to apply the conversion techniques to other carbon nanomaterials to create unique three-dimensional materials for additional applications.