Investigation of Oxidation-Resistant Coatings on Graphite and Molybdenum in Two Arc-Powered Facilities

A number of leading-edge specimens of ATJ graphite and 0.5-percent titanium-molybdenum alloy were tested in a 6-inch subsonic low-pressure arc-powered tunnel and a 1,500-kw subsonic arc jet to determine the effectiveness of several refractory coatings in preventing the oxidation of these materials. The results indicate that the siliconized coating for the ATJ graphite and the W-2 and Durak MG coatings for the titanium-molybdenum alloy provide adequate protection at temperatures up to 3,000 F for the durations of the tests in these facilities, approximately 70 seconds in the arc tunnel and approximately 10 minutes in the arc jet. Weight losses (less than one-half of 1 percent) experienced by a few of the coated specimens indicate that tests of longer duration in these environments may prove deleterious and that the stability of these coatings may be depreciated under the low-pressure environmental conditions encountered during reentry.