Characterization and wear behavior of pulsed electrode surfacing coatings

Pulsed electrode surfacing (PES), which is a micro-welding process, was ado pted for depositing a sintered electrode of a mixture of TiC + 2%B + 2% Fe, on an AISI 8030 steel substrate. Different circuits were used and the depo sition was carried out during 50 mus, with pulses having a current amplitud e of 50 A and different frequencies of 50, 75 and 100 Hz. Sample characteri zation has been performed by using scanning electron microscopy (SEM) coupl ed with energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (X RD). Ball-on-disc tests were carried out to determine the friction and wear properties for every processing condition. The tests were conducted under non-lubricated conditions, in air with a relative humidity of 50 +/- 2% and ambient temperature of 24 +/- 1 degreesC. Alumina balls of 6 mm diameter w ere loaded with a normal force of 5 N. The specimens were rotated there at a velocity of 0.1 in s(-1) for a sliding distance of 1000 m. It was determi ned that the steady-state friction coefficients did not vary with the depos ition parameters (mu (average) = 0.53) although the running in friction coe fficient values were different, due to variation in the average roughness, R-a, of the treated samples. The wear resistance was evaluated by calculati ng the wear factor, k, considering that the wear volume is linearly proport ional to the load and the sliding distance. Wear scar morphologies, on both coatings and alumina balls, were examined by using SEM and X-ray elemental mapping in order to establish the wear mechanism. (C) 2001 Elsevier Scienc e B.V. All rights reserved.