Degradation of Sputter-Deposited Nanocomposite MoS2 Coatings for NIRCam during Storage in Air

摘要

The Focus and Alignment Mechanism (FAM) in NIRCam on the James Webb Space Telescope will bernlubricated with nanocomposite sputter-deposited MoS2 coatings. To respond to concerns regarding howrnexposure to humid air during storage would affect performance, a study was conducted involving real-timern(i.e., unaccelerated) storage of coatings in air at 59% RH for over two years. Pin-on-disk friction testingrnshowed that the endurance of the coatings dropped significantly during storage, but still providedrnacceptable margin for FAM. The endurance results correlated well with X-ray Photoelectron Spectroscopyrnresults that measured the conversion of MoS2 to nonlubricating MoO3 during storage.