Soft X-Ray Photoelectron Spectroscopy Study of the Interaction of Cr with MoS2(0001)
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 MoS2(0001) surface with core-level and valence- band soft X-ray photoelectron spectroscopy employing synchrotron radiation (hv=150 to 400 eV). Cr vapor-deposited at room temperature formed relatively flat films on MoS2(0001). 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 MoS2(0001) 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 metal/lubricant adhesion.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 14, 1994
- Accession Number
- ADA276916
Entities
People
- David K. Shuh
- Jeffrey R. Lince
- Jory A . Yarmoff
- Stephen V. Didziulis
- Thomas D. Durbin
Organizations
- The Aerospace Corporation