Accession Number : AD0830429

Title :   THE CHARACTERIZATION OF METAL OXIDE FILMS.

Descriptive Note : Final rept. Sep 65-Nov 67,

Corporate Author : LEHIGH UNIV BETHLEHEM PA INST OF RESEARCH

Personal Author(s) : Kim, H. J. ; Runk, R. B. ; Polek, J. R. ; Trivedi, R. C. ; Coughlin, R. W.

Report Date : JAN 1968

Pagination or Media Count : 82

Abstract : A theoretical and experimental study of the characterization of thin oxide films formed on iron and two-phase iron-carbon alloys was conducted. Three complimentary experimental approaches were utilized: thin film formation on two-phase iron-carbon bulk materials as related to morphology; the synthesis of iron-carbon alloy powders; and the initial oxidation of iron and iron-carbon alloy powders. Mechanisms have been proposed for the low temperature oxide growth over the typical narrow lamellar structure of pearlitic alloys. It was found that high-surface-area, low-carbon, iron-carbon alloy powders can be synthesized with varying carbon-to-iron ratios, and free from impurities, utilizing a fluidized-bed gas carburization process. Similar efforts to synthesize the iron carbides Fe2C and Fe3C are also described. Characteristic three-stage kinetic oxidation processes for reduced and unreduced iron powders are also described, indicating reaction of adsorbed hydrogen with oxygen, one monolayer oxygen chemisorption on high energy sites, further oxygen chemisorption on low energy sites, and growth of oxide nuclei. The latter two processes appeared to correspond with Uhlig's recent two-stage oxidation theory related to constant density and diffuse space changes. (Author)

Descriptors :   *FILMS), (*IRON OXIDES, (*OXIDATION, FILMS), IRON, IRON ALLOYS, CARBON ALLOYS, POWDER METALS, PREPARATION, AUSTENITE, PEARLITE, FLUIDIZED BED PROCESSES, IRON COMPOUNDS, CARBIDES, SYNTHESIS(CHEMISTRY), REACTION KINETICS, CHEMISORPTION, NUCLEATION, MICROSTRUCTURE.

Subject Categories : Physical Chemistry
      Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE