Non-catalytic coatings for hypersonic vehicle applicationsCVD coatings of boron-oxygen-silicon and aluminum-boron-oxygen and silicon compositions were applied to alpha 2 and gamma titanium-aluminide alloys, and tested under simulated earth reentry conditions to evaluate oxidation protection, recombination effifiency and total emittance under cyclic exposures between temperatures of 300 and 1255 K. The degree of oxidation protection afforded to the alloys was evaluated from the amount of specimen weight gain after a 100 hour exposure to air at atmospheric pressure and at a temperature of 1255 K. Data are presented for two types of coatings, a monolithic and a multilayer, which have recombination efficiencies from 0.005 to 0.020 after ten one-half hour long simulated reentry cycles. Total normal emittance was 0.80 or greater and weight gain was less than 10 g/sq m both coating types. Compositional and morphological changes resulting from the exposures are discussed in relation to time-dependent variations in recombination efficiency.
Document ID
19900051383
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Cunnington, G. R. (Lockheed Missiles and Space Co. Palo Alto, CA, United States)
Robinson, J. C. (Lockheed Missiles and Space Co., Inc. Palo Alto, CA, United States)
Clark, R. K. (NASA Langley Research Center Hampton, A, United States)