EFFECTS OF LOAD AND SLIDING SPEED ON THE WEAR BEHAVIOR OF PLASMA-SPRAYED TIC-NICRBSI COATINGS

The use of thermally sprayed coatings is a way of reducing wear and fr ictional losses. However, a limited number of studies have been done o n the tribological behaviour of wear resistant coatings. Results of an investigation to evaluate the effects of some wear test conditions on air and vacuum plasma-sprayed (APS and VPS) TiC-NiCrBSi coatings usin g a pin-on-disk tribometer have been presented in this research. Room temperature tests varying the load and sliding speed have been perform ed in order to understand the effects of these parameters on the coati ngs' wear and friction behaviour. Results have shown that load, slidin g speed, and the plasma spray process affect the wear resistance and t he friction behaviour of thermally sprayed coatings considerably. High er loads, during sliding, led to higher wear rates for both air and va cuum plasma sprayed coatings. In both systems, APS and VPS, the rate o f change of total wear versus load was decreasing. Steady state coeffi cients of friction were constant with no major transitions in friction behaviours at all the studied loads. Higher sliding speeds led to dec reased wear rates for both air and vacuum plasma sprayed coatings. In both systems a transition from a more severe to a milder form of wear seemed to occur at a point between 0.44 and 1 m/s. The trend of the av erage coefficient of friction during the tests was to decrease with sl iding speed, especially after the break-in. VPS processing always resu lted in higher wear resistant coatings than the APS coatings. (C) 1998 Elsevier Science S.A. All rights reserved.