Research At the Center for Advanced Friction Studies
INTRODUCTION: Because of their lightweight and high heat resistance, many airplanes are now equipped with Carbon/Carbon composite brakes. The composite is a heat-treated carbon fiber needled preform densified using a Chemical Vapor Deposition technique. As an example, these materials are now used on BOEING’s 747 for a reported weight savings of 1600 pounds!
Optical Microscope Image of Friction surface of Carbon/Carbon Composite after friction testing.
Scanning Electron Microscope Image of Carbon Fibers surrounded by Graphite Matrix.
DISCUSSION: As part of my internship at CAFS, I performed friction tests on Carbon/Carbon composites. The images above are some of those collected after various friction tests. In the picture from the optical microscope you will notice that the graphite has formed in layers surrounding each carbon fiber. They appear colored when viewed under polarized light. The SEM image shows how shearing can occur between the graphite layers because they are held together by weak Vanderwalls forces. I enjoyed the challenge of materials science and the experiece I gained with the OM and SEM.