Accession Number:

AD0271458

Title:

THE EFFECT OF CONCURRENT STRESSING ON THE AIR OXIDATION OF TANTALUM

Descriptive Note:

Corporate Author:

METAL HYDRIDES INC BEVERLY MASS

Personal Author(s):

Report Date:

1961-04-01

Pagination or Media Count:

1.0

Abstract:

The air oxidation of unstressed tantalum, measured by decrease in metal thickness over the temperature range 427 to 649 C 800 to 1200 F was found to proceed initially according to a parabolic rate law. At temperatures of 510 to 649 C 950 to 1200 F the oxidation changed from parabolic to linear behavior, after times at temperature sufficient to allow breakdown of the protective initial oxide scale. The transition time from parabolic to linear oxidation decreased with increasing temperature. Linear and parabolic rate constants were evaluated for the scaling process. Activation energies of 28,600 calmol for linear oxidation, and of 40,800 calmol for parabolic oxidation were determined. Oxidation tests in the stressed condition, 20,000 and 24,000 psi increased the parabolic scaling rate about two to four times over than of unstressed samples at the same temperature. No enhancement of the linear oxidation rate was noted. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE