Influence of the heat treatment on the tribological behavior of a Ni-P-BN(h) autocatalytic composite coating

Sliding wear experiments were performed in order to evaluate the influence of the heat treatment temperature on both friction coefficient and wear res istance of a Ni-P-BN(h) composite coating with 33 vol% BN(h), thickness of 18.1 mu m and 5.5 wt% P deposited on a 316L stainless steel substrate. The as-deposited samples have been heat treated for Ih at 200, 300 and 400 degr ees C in an argon atmosphere. X-ray diffraction analysis was employed in or der to study the phase transformation produced during heating. The tribolog ical behavior of the coatings under non-lubricated conditions has been stud ied by means of a pin-on-disc test. Microhardnesses of the coatings with an d without heat treatment are also reported. It has been shown that the Ni-P -BN(h) composite autocatalytic coatings heat treated at 400 degrees C, whic h had the highest hardness, exhibit the lowest wear factor of 4.87 x 10(-7) mm(3)(N m)(-1) and this value is nearly one order of magnitude smaller tha n for all the other Ni-P-BN(h) composite coatings analyzed in this study. D ue to the lubricating action of BN(h), the wear coefficient, k, was found t o be two orders of magnitude smaller than the wear factor of 5.12 x 10(-5) mm(3)(N m)(-1) reported for a conventional Ni-P autocatalytic coating which has been heat treated at the same temperature of 400 degrees C. It was det ermined that the wear mechanism involved in the wear of the Ni-P-BN(h) comp osite was pure adhesive. (C) 1999 Published by Elsevier Science S.A. All ri ghts reserved.