COLLABORATIVE RESEARCH AND DEVELOPMENT (CR&D) Delivery Order 0068: Anti- fretting Coatings Research and Development

摘要

This research in support of the Air Force Research Laboratory Materials and Manufacturing Directorate was conducted at Wright-Patterson AFB, Ohio from 14 November 2006 through 1 February 2008. This task worked to develop and test anti-fretting coating systems for application to Al and Ti alloys able to withstand high cyclic loadings in contact with steel counterparts. Fretting wear is an accumulation of damage that occurs at component interfaces that are subjected to high contact stresses coupled with low amplitude oscillation. In metallic contacts, surface oxides, adhesion, and material transfer play a primary role in the initial stages of fretting wear degradation. Given these behaviors, the focus of this study was to determine the effect of temperature on inter-metallic fretting wear between Ti6Al4V (Titanium, 6% Aluminum, 4% Vanadium) and cold-sprayed, commercially pure nickel coatings. The results presented herein show that increased temperature decreases friction through the formation of a uniform NiO layer, and by the reduction of Ni2O3 in the contact. In addition, it was found that a localized minimum friction coefficient is achieved at approximately 300 degrees Celsius, above which the friction increases slightly due to the annealing of the cold sprayed coatings.