ZRPT3 AS A HIGH-TEMPERATURE, REFLECTIVE, OXIDATION-RESISTANT COATING FOR CARBON-CARBON COMPOSITES

C-C composites are severely limited by oxidation in high-temperature environments. As a possible means of reducing this oxidation, we have investigated Engel-Brewer (E-B) intermetallic films formed on carbon from multilayers of Zr and Pt. Stoichiometric amounts of the individual metals were deposited on graphite and annealed in vacuum by irradiating with an electron beam. The resulting films are adherent and, when analyzed by XPS and SEM, the data show that complete mixing had occurred and the metal layers had fully reacted to form ZrPt3. In addition, a phenolic resin/graphite fiber material was coated with thin films of Zr/Pt. Preliminary evidence suggests that the E-B compound formed on heating provides some degree of protection from a 2800-degrees-C oxidizing flame. Additional results on graphite indicate that these films could decrease the heating rate for a fully graphitized carbon-carbon composite by a factor of 4. The protection of the graphite and resin/fiber composites is due to the oxidation resistance of the ZrPt3 and to the reflectivity of the Zr/Pt coating, which reduces the heat load on the substrate for short time and high-temperature applications. Consequently, it is anticipated that these coatings will be useful for protecting carbon-carbon composites in high-temperature applications.