Accession Number:

ADA261547

Title:

Interaction of O2 with the Fe(.84)Cr(.16)(001) Surface Studied by Photoelectron Spectroscopy

Descriptive Note:

Corporate Author:

AEROSPACE CORP EL SEGUNDO CA TECHNOLOGY OPERATIONS

Report Date:

1992-07-15

Pagination or Media Count:

42.0

Abstract:

The surface oxidation of a steel-like alloy was investigated to help determine how the efficiency of lubricant additives such as lead naphthenate might be affected by the chemical state of a high-Cr steel bearing surface. Soft X-ray photoelectron spectroscopy SXPS hv 130 - 600 eV employing synchrotron radiation and X-ray photoelectron spectroscopy XPS hv 1486.6 eV employing Al-K alpha X rays were used to study the effect of molecular oxygen adsorption 1 to 104 L, where 1L equivalent 10 -6 Torr-sec on the 001 surface of Fe. 84Cr.16 at room temperature. The use of multiple photon energies allowed a qualitative determination of the distribution of species in the oxide film perpendicular to the surface. Prior to oxidation, Fe.84Cr.16 samples were annealed to different temperatures to produce varying concentrations of Cr in the top few monolayers of the 001 surface. The differences between the oxide films produced on these different surfaces were determined with SXPS using primarily the Fe 3p, Cr 3p, and valence levels. Small amounts of carbidic carbon less than 1 monolayer that had segregated to the 001 surface of the Fe84Cr. 16 alloy during initial sputteranneal treatments were removed during the first approx. 5 L O2 exposure. In general, the resistance of the Fe.84Cr.16001 surface to oxidation was directly related to the initial Cr concentration at the surface. The oxide films were richer in Cr compared to the bulk concentration for the lowest 02 exposures, and became increasingly enriched in Fe for increasing exposures, in a agreement with studies by other groups.

Subject Categories:

  • Properties of Metals and Alloys
  • Lubricants and Hydraulic Fluids

Distribution Statement:

APPROVED FOR PUBLIC RELEASE