Mh. Staia et al., Part II: tribological performance of Cr3C2-25% NiCr reactive plasma sprayed coatings deposited at different pressures, SURF COAT, 146, 2001, pp. 563-570
The present work has been undertaken to determine the sliding wear behavior
of plasma sprayed coatings deposited using different pressure conditions,
ranging from 300-1200 mbars, in a nitrogen atmosphere using a controlled at
mosphere plasma spray system (CAPS). The spraying distance and the substrat
e temperature during deposition were also varied. Sliding wear tests were p
erformed against WC-6% Co balls using a pin-on-disc tribometer. The highest
sliding wear resistance was obtained for the samples processed at a pressu
re of 1200 mbar, a spraying distance of t20 mm and substrate heating to 600
degreesC, for which an average value for the specific wear coefficient, k,
of 5.72 E-07 mm(3)/N in was determined. An increase in the spraying distan
ce from 120 to 140 mm, keeping all the other parameters constant produced a
n increase in the wear volume of 33%. However, for the same spraying pressu
re and distance, cooling the substrate resulted in an increase in the wear
volume of nearly 1125% when compared to the coating produced with optimum c
onditions. In addition, a decrease in wear resistance of 83% occurred when
the pressure was varied between 1200 to 300 mbar, which was attributed to a
decrease in the carbide deposition efficiency, xi, defined as the relation
ship between the (Cr3C2) coating/(Cr3C2) powder. This new material, consist
ing of chromium carbide, Ni-Cr, carbo-nitride phase and graphitic carbon ha
d excellent sliding wear resistance that was approximately 23 times better
than that reported for conventional HVOF Cr3C2-25NiCr coatings. (C) 2001 El
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