THE EFFECT OF CONCURRENT STRESSING ON THE AIR OXIDATION OF TANTALUM

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 cal/mol for linear oxidation, and of 40,800 cal/mol 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)

Document Details

Document Type
Technical Report
Publication Date
Apr 01, 1961
Accession Number
AD0271458

Entities

People

  • B.a. Wilcox
  • F.h. Beck

Tags

Communities of Interest

  • Materials and Manufacturing Processes

DTIC Thesaurus Topics

  • Chemical Compounds
  • Chemical Reaction Properties
  • Chemical Reactions
  • Energy
  • Heat Of Activation
  • Metals
  • Ores
  • Oxidation
  • Oxides
  • Oxygen Compounds
  • Rocks And Deposits
  • Tantalum
  • Thickness
  • Transitions

Readers

  • Approximation Theory.
  • Materials Science and Engineering.
  • Thin Film Deposition Science.