Thermoplastic polymer matrix composites are used as coating materials for t
he bore of downhole tubulars used as water injectors in the oil industry. T
hese coatings are primarily employed for corrosion resistance but must also
resist mechanical damage from the inspection tools lowered at speed down t
he tubing. This mechanical damage is produced by the wearing action of the
supporting wire against the coating (wireline wear) and by direct impact of
the tool against the coating. Filler materials are added to these polymeri
c coatings and these additions are known to affect the wear resistance of t
he coating. In this study, three types of thermoplastic polymeric coatings
were subjected to wear tests. Both abrasive wear tests - using silicon carb
ide papers as the abrasive, and wireline wear tests, utilising a true tribo
couple consisting of the coating and a length of "slickline" wire on a modi
fied pin on disc apparatus - were carried out to study the wear resistance
of these three coatings. Detailed scanning electron microscopy was performe
d on the wear tracks produced to elucidate the wear mechanism and in partic
ular the role of fillers. In abrasive wear a polymer with a brittle filler
has a higher wear rate than an unfilled polymer due to the fact that the br
ittle fillers can be easily fractured and detached from the polymer matrix.
In general, the weak bond between the filler and a thermoplastic polymer m
atrix leads to the filler particles detaching from the matrix causing enhan
ced wear. In wireline wear the presence of voids and unmelted particles is
particularly deleterious. (C) 2001 Elsevier Science B.V All rights reserved
.