Lubrication of Mo, W, and their Alloys with H2S gas admixtures to room temperature air

The in sim lubrication of molybdenum and tungsten using admixtures of hydrogen sulfide to room temperature and pressure air was achieved, Raman spectroscopy confirmed the presence of molybdenum disulfide and tungsten disulfide solid lubricants on elemental molybdenum and tungsten specimens, respectively. Pin-on-disk experiments were conducted with elemental molybdenum, elemental tungsten, and alloys of molybdenum and tungsten in atmospheres containing hydrogen sulfide. Friction coefficients were continuously recorded and comparisons between the sliding friction coefficient in air and in the hydrogen sulfide atmospheres were evaluated. In general, hydrogen sulfide admixtures reduced the friction coefficient for all materials containing molybdenum or tungsten. Friction coefficients for self-mated elemental molybdenum and self-mated elemental tungsten were reduced to mu = 0.15 with hydrogen sulfide admixtures to air of 5% and 15%, respectively. In some cases friction coefficients as low as mu = 0.08 were recorded. (C) 1999 Published by Elsevier Science S.A. All rights reserved.