• Version
• 172 Downloads
• 2.01 MB File Size
• 1 File Count
• November 2, 2016 Create Date
• November 2, 2016 Last Updated

National Advisory Committee for Aeronautics, Report - Friction, Wear and Surface Damage of Metals as Affected by Solid Surface Films

This paper is based on NACA research data Obtained
during a series of investigations in the field of lubrication,

friction, and wear conducted from 1946 to 1954. Each m— ‘

vestigation in the series had specific objectives, but all were
directed toward determination of the role of surface films
in friction and wear.

As is well known, the presence of a contaminating film
between sliding surfaces can have a marked effect on friction,
wear, and surface damage. (A contaminant is defined as
any material other than those comprising the sliding sur-
faces.) Some contaminants are beneficial (lubricants), while
others are detrimental (abrasives). Considerable evidence
(refs. 1 to 8) indicates the importance Of solid surface films
to the compatabih'ty of sliding surfaces. Physical and
chemical surface changes have been associated with satis-
factory and with unsatisfactory operation of metallic sliding

surfaces (ref. 2). As an example, “run-in” has long been
known to be effective in improving the performance and the
load-carrying capacity Of surfaces. Among the factors that
lead , to satisfactory performance 'are the formation and
maintenance of certain beneficent solid surface films. ,
Such solid films are commonly formed on sliding surfaces
by use of extreme-pressure additives in lubricants; chemical
films of low shear strength or of low melting point are formed
by reaction between additives and the sliding surfaces under
conditions of extreme pressure and temperature. Theories
for the mechanism of extreme pressure lubrication are dis-
cussed in references 3 and 8.