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National Advisory Committee for Aeronautics, Technical Notes - Bonding of Molybdenum Disulfide to Various Materials to Form a Solid Lubricating Film - I - The Bending Mechanism

The use of molybdenum disulfide MbSZ as a solid film lubricant in
applications where designs or temperatures preclude liquid lubricants is
dependent upon successful bonding of the powder to the surface to be
lubricated. An experimental investigation was conducted to determine
the basic mechanism of bonding and to extend application‘of the bonding
to a variety of materials. The results indicated that when Mng was
applied to a surface as a mixture of MoSg powder and some liquid
vehicles, the liquid vehicle decomposes or polymerizes to.a resin which
binds the particles of Mng together and to the surface to be lubri-
cated. By use of resin-forming viscous liquids such as asphalt—base
varnish, silicones, glycerine, ethylene glycol, polyglycol ether, and
corn syrup, MoSZ can be bonded to materials such as steel, aluminum,
brass, stainless steel, and glass. The reduction of Fe205, formed by
preheating steel in air, to Fe504 by one of the liquid vehicles (syrup)
improves the frictional properties of the solid lubricating film.

Molybdenum disulfide M083 used as a solid-film lubricant has
been shown to have high load-carrying capacity at high pressures (refer—
ence l), to maintain low coefficients of friction over a wide range of
sliding velocities (reference 2); and to maintain a low friction coef-
ficient during its oxidation (which begins at a very low rate at 7500 F)
as long as an effective subfilm of MbSZ remains (reference 3).
Such desirable properties are extending the use of NbSZ, particularly where
designs or temperatures preclude liquid lubricants, such as compressor
blade-root lubrication (reference 4). The low coefficient of friction
and minimization of surface damage are dependent upon the relatively
low shear strength and high load-carrying capacity of mesa, but lubri-
cation is sustained only as long as the material remains between the
rubbing surfaces in effective amounts. The life of an effective film
is dependent upon its resistance to being ploughed up and pushed out of
the wayu The resistance to ploughing and removal is dependent upon the
toughness of the film and its tenacity for one or both of the sliding
surfaces. With mesa, of fixed.toughness, shear strength, and load-
carrying capacity, an increase of the lubricating life may be possible
by an increase in the tenacity of the bond to metals.