Secondary bonding of carbon/carbon composites

Abstract

Increased use of carbon/carbon composites has produced design concepts which require secondary bonding. Secondary bonding is, in some instances, the primary attaching method for rocket nozzle components. In other designs, secondary bonding is utilized in addition to mechanical fastening devices. Secondary bonding of carbon/carbon interfaces provides design flexibility and also alleviates complicated fabrication problems. A secondary bond study program was conducted in which interlaminar shear strength data were obtained for four materials and four different processes, including graphitization to 2480°C (4500°F). Both room temperature and elevated temperature 2204°C (4000°F) data were obtained. Shear strengths up to 12.41 MPa (1800 psi) were measured at 2204°C (4000°F); conversely, thin bond lines produced values as low as 0.41 MPa (60 psi). Results indicate that secondary bonding is a viable process and can be utilized to join carbon/carbon structures.