TECHNIQUES FOR IMPROVING WEAR LIFE OF A SOLID-FILM LUBRICANT IN VACUUM

The objective of this program was to investigate methods for improving wear-life performance of a solid-film lubricant at elevated temperatures in a vacuum environment. The film formulation selected for this study was a MoS2-PbS mixture bonded with a ceramic-metal oxide binder. Wear-life tests were conducted on a vacuum test rig to determine the degree of improvement. Test conditions were pressures, approximately 10 to the -6th power torr speed, 600 revolutions per minute load, 25 and 52 pounds temperature, 200 to 1000 F. Test specimens were a disk and two rub blocks. Only the disk was coated and was rotated between the two rub blocks placed 180 deg apart. Specimen Materials were 4130, 4340, Rex AAA, M-10, 440C and Rene 41 alloys. Three techniques were investigated to determine effectiveness for improving wear-life performance by producing a denser film. These included two methods of mechanical compressing polishing and rolling the film. The third was a process of double deposition. Results were compared to conventionally sprayed films. The results indicate that polishing and rolling provide a very limited improvement but that the double-deposition method offers considerable wear-life improvement.