Tribological characteristics of elastomers lubricated with EALs and contaminated EALs

Abstract: The friction and wear characteristics of several elastomers are
investigated under sliding contact lubricated by environmentally adapted
lubricants with varying degrees of contamination. The elastomers studied
are flat strips of Nitrile Butadiene rubber (NBR), Hydrogenated Nitrile
Butadiene Rubber (HNBR), and Fluorocarbon Rubber (FKM) and O-Rings of both
molded and extruded NBR and FKM. The lubricants used are uncontaminated
Complex Ester and Polyolester as well as both Aged and Un-Aged Polyolesters
with 5\% Water Content as well as a commercial synthetic based turbine oil
and a commercial mineral oil based turbine oil. Initial experiments were
conducted using a Cameron-Plint test rig with a steel cylinder sliding in
the longitudinal direction with a reciprocating motion against a curved
elastomer specimen to avoid any edge contact. Sliding velocities were
maintained low to reduce the thermal effects often associated with
elastomer friction. The results from these experiments demonstrate the
compatibility of the different elastomers with the various lubricants and
load configurations. Further testing was conducted using the Cameron-Plint
machine with O-ring material sliding against flat steel plates results of
which validated the use of synthetic ester in lieu of mineral base oils in
the case of sealing surfaces of proper roughness and found that extruded
NBR performed best of the tested materials. Experiments were also
conducted using an SRV Optimol test rig at higher frequencies with a steel
cylinder in contact with an elastomer disc. The results from the SRV test
rig conflicted significantly with those of the Cameron-Plint rig due to the
differences in contact geometry of the tests. Other experiments conducted
using an Abrasive Test machine which reciprocated a steel ring against
elastomer specimens produced no worthwhile results other than demonstrating
the durability of the elastomer specimens when operating in the elasto-
hydrodynamic lubrication regime.