Journal of Materials Science, Vol.29, No.22, 5875-5879, 1994
Synthesis and Characterization of a High-Temperature Oxide Lubricant
PbMoO4 is a potential solid lubricant for use at elevated temperatures in oxidizing environments. Pulsed laser deposition (PLD) was utilized to grow thin films of this material because it allows good control over film chemistry and crystallinity. Films were grown at different substrate temperatures in vacuum and in partial pressures of oxygen. The chemistry and crystallinity of the films were evaluated using X-ray photoelectron spectroscopy, Raman spectroscopy, and glancing angle X-ray diffraction. Friction coefficients and wear lives were measured using a ball-on-flat tribometer at room temperature and 700 degrees C. Films deposited in vacuum, at room temperature and at 300 degrees C, were oxygen deficient. To adjust chemistry and crystallinity, films were grown in a partial pressure of oxygen (i.e. 6.7 x 10(-1) Pa). Stoichiometric, crystalline films of PbMoO4 were produced when films were grown at 300 degrees C in this environment. PbMoO4 films were lubricious (mu = 0.35) and long lived at 700 degrees C, but at room temperature had high friction and failed quickly. The properties of the films grown at the different conditions are discussed.