Page 319 - The Tribology Handbook

Solid lubricants and coatings c5

URNISHED FILMS
Effects of operational variables
Results obtained from laboratory tests with a ball sliding on a film-covered disc. Applicable to MoS,, WS2 and related
materials, but not to PTFE and graphite.
pin
lo2 103

lo4 - z
P
+
0
- 0.2 - 0.21:
U
0
c z
w
- 0.1 - 0.1 0
10 U
U
u)
8
- 1
0 25 50 70 106 0 200 400 600
Ol0 r. h . OC 0.01 0.1 1 10
P
RELATIVE HUMIDITY TEMPERATURE FILM THICKNESS
Acidity may develop at high Life limited by oxidation, but Difficult to produce films
r.h. Possibility of corrosion or MOO, is not abrasive. Tem- > 10 pm thick except at high
loss of film adhesion. perature lowers humidity. r.h.

pin CLA Ibf
r-+-+-+* 1 IO lo2 lo3 lo4
I
I
I

- 0
0.01 0.1 1 IO lo2 lo3 104
pm CLA

SURFACE ROUGHNESS LOAD
Olptimum depends on method As load increases, a greater pro-
of surface preparation. Abra- portion is supported by the
sion, 0.5 pm; grit-blast, 0.75 substrate. A similar trend occurs
PITI; grinding, 1.0 pm; turning, as the substrate hardness in-
1.25 pm. creases.

No well-defined trend exists between film life and substrate hardness. Molybdenum is usually an excellent substrate for
MoS, films. Generally similar trends with film thickness and load also apply to soft metal films.
C5.2