EFFECT OF SLIDING SPEED ON THE FRICTIONAL BEHAVIOR AND WEAR PERFORMANCE OF BORIDED AND PLASMA-NITRIDED W9Mo3Cr4V HIGH-SPEED STEEL

This study investigated the effect of sliding speed on the friction and wear behaviors of plasma-nitrided (PN) and bonded (W9M03Cr4V) steels. The PN process was carried out in a dc-plasma system at a temperature of 923 K for 6 h in a gas mixture of 80 % N-2-20 % H-2 under a constant pressure of 5 mbar. The bonding process was carried out in Ekabor-II powder at a temperature of 1223 K for 6 h. X-ray diffraction analysis on the surface of the PN and bonded steels revealed the presence of FeB, Fe2B, CrB, MoB, WB, FeN, Fe2N, Fe3N and Fe4N compounds. The wear tests were carried out in a ball-disc arrangement under dry friction conditions at room temperature with an applied load of 10 N and with sliding speeds of (0.1, 0.3 and 0.5) m/s at a sliding distance of 1000 m. The wear surfaces of the samples at the different sliding speeds were analyzed using SEM microscopy and X-ray energy-dispersive spectroscopy EDS. The friction coefficients of the nitrided and bonded W9Mo3Cr4V steels varied from 0.42 to 0.61, and from 0.33 to 0.52, respectively. As a result of the wear, the friction coefficient was observed to decrease with an increase in the sliding speeds of the PN and the bonded AISI W9Mo3Cr4V steel while an increase was observed in the wear resistance.