The Effect of Hydrochloric Acid Pretreatments on 440C Steel Surface Composition and the Adhesion and Endurance of Sputter-Deposited MoS2 Solid Lubricant Films
Abstract
The effects of substrate pretreatment on substrate surface chemistry and on film-substrate adhesion, and film endurance (wear life) of sputter- deposited molybdenum disulfide (MoS2) on 440C bearing steel were investigated. Specifically, 20% hydrochloric acid/ethanol mixtures were used to etch the steel surface prior to deposition or x ray photoelectron spectroscopy (XPS). Acid etching inhibited fractures at the film-substrate interface generated by brale indentation testing. XPS indicated that the acid etching removed an iron-rich oxide surface layer, exposing a chromium-rich oxide underlayer on the steel matrix. Acid etching did not significantly affect thrust-washer sliding near life. Molybdenum disulfide is a useful solid lubricant for space applications because of its low friction, negligible vapor pressure, and tribological insensitivity to temperature (relative to liquid lubricants). Sputter deposition is a useful process for applying MoS2 onto component surfaces; the process creates a uniformly thick coating. MoS2 is routinely used in release mechanisms and on sliding electrical contacts. There is also a growing interest in using MoS2 in precision bearings. Recently, there has been a significant effort to better understand the relationship between film processing conditions and resultant film structure and composition properties.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 19, 1991
- Accession Number
- ADA241077
Entities
People
- M. R. Hilton
- P. D. Fleischauer
- R. Bauer
- S. V. Didziulis
Organizations
- The Aerospace Corporation