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 be lubricated with nanocomposite sputter-deposited MoS2 coatings. To respond to concerns regarding how exposure to humid air during storage would affect performance, a study was conducted involving real-time (i.e., unaccelerated) storage of coatings in air at 59% RH for over two years. Pin-on-disk friction testing showed that the endurance of the coatings dropped significantly during storage, but still provided acceptable margin for FAM. The endurance results correlated well with X-ray Photoelectron Spectroscopy results that measured the conversion of MoS2 to nonlubricating MoO3 during storage.