Accession Number:

ADA276916

Title:

Soft X-Ray Photoelectron Spectroscopy Study of the Interaction of Cr with MoS2(0001)

Descriptive Note:

Corporate Author:

AEROSPACE CORP EL SEGUNDO CA TECHNOLOGY OPERATIONS

Report Date:

1994-01-14

Pagination or Media Count:

37.0

Abstract:

The solid lubricant MoS2 must exhibit good adhesion to high-Cr steels used in moving mechanical assemblies on spacecraft to provide an effective antiwear lifetime. The adhesion can be maximized by tailoring the interfacial reactivity between the Cr at the steel surface and MoS2. To this end, we studied the interaction of Cr with the MoS20001 surface with core-level and valence- band soft X-ray photoelectron spectroscopy employing synchrotron radiation hv150 to 400 eV. Cr vapor-deposited at room temperature formed relatively flat films on MoS20001. The Cr underwent a limited chemical reaction with the MOS2 substrate to form a chromium sulfide and Mo metal. The Mo metal formed a thin layer between the Cr film and the MoS2 substrate. In contrast, reacted S was incorporated throughout the Cr film, with its concentration enhanced at the surface. Annealing the Cr-covered sample drove the reaction between Cr and MoS2, forming additional Mo metal that alloyed with Cr, and several adsorbed S species on the Cr film surface. Annealing also caused partial coalescence of the Cr- containing portion of the film, uncovering parts of the Cr-Mo alloy. The reactivity of Cr with respect to MoS20001 is greater than that of Fe and somewhat less than that of Mn. The results indicate that cleaning the surface of a steel device before MoS2 film deposition will expose bare Fe and Cr metal, which could increase the metallubricant adhesion.

Subject Categories:

  • Adhesives, Seals and Binders
  • Properties of Metals and Alloys
  • Lubricants and Hydraulic Fluids
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE