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Oxidation of columbium and coated columbium alloys

Technical Report ·
OSTI ID:4306354
Oxidation of the Nb alloys FS-85, SU-31, and a complex disilicide coating/SU-31 and FS-85 alloy systems were studied at 1400 to 2700 deg F at 1 atm and 50 cm/s flow rate of air. For studies of the uncoated alloys, the flow rate and pressure dependence of the alloys were also investigated. Methods included thermogravimetric measurements of oxidation rates and studies on reacted specimens by means of x-ray diffraction, metallographic techniques, and electron microprobe analysis. Two anomalies in the temperature dependence of the oxidation rate were observed for both alloys and were related to the oxides formed. The SU-31 alloy has the best oxidation resistance. The oxidation mechanism of the alloys is discussed along with the mechanism of protection afforded by the complex disilicide coating system. The coating did not fail after 1000 hours of oxidation. (auth)
Research Organization:
Army Materials and Mechanics Research Center, Watertown, Mass. (USA)
NSA Number:
NSA-29-024644
OSTI ID:
4306354
Report Number(s):
AD--768153-9-GA; AMMRC-TR--35
Country of Publication:
United States
Language:
English