The challenge, however, was to put it into a usable foals i. Epoxy holds the fibers in place, distributes the load among them, and protects them from the environ- ment. To make an aircraft part, strips of epoxy tape with fibers running through it are laid in remold in directions that will reinforce 27 OCR for page 28 Layers of woven Kewlar fibers strengthen composite downhill snow skis while reducing weight and damping vibration. Advanced composite materials are used in many sporting goods, whose high performance provides a competitive advantage. High heat and pressure transform the epoxy into a solid, lightweight part.
Boron fiber is expensive.
So parallel work in England and Japan focused on graphite as a less expensive high-strength fiber. Graphite is a form of carbon, and its fibers are made by transforming organic fibers such as rayon, acrylic, or pitch. It began with an acrylic fiber that was wound on steel racks to stretch the fiber and align its long molecules into stronger, parallel orientation. The fiber was heated at low temperature to stabilize the orientation, then cut into strands and slowly baked in a furnace with inert gas-usually nitrogen to burn away impurities. The remaining graphite fibers were treated with chemicals to help them bond to a resin matrix.