Pulsed plasma nitriding of high velocity oxy-fuel sprayed Inconel 625 coatings

Abstract

A hardening of high velocity oxy-fuel sprayed Inconel 625 coating systems was performed by pulsed plasma nitriding treatment. After deposition of an Inconel 625 coating, samples were pulsed plasma nitrided at 520 degrees C for 12 h in a gas ratio of 3:1 N-2 and H-2 under a constant pressure of 2.5 x 10(2) Pa. Pulsed plasma nitriding improved the microhardness of the high velocity oxy-fuel sprayed Inconel 625 coating from 355 to 401 HV0.05. The high velocity oxy-fuel-sprayed Inconel 625 coating after pulsed plasma nitriding process showed excellent corrosion resistance as well as a reduction of both the friction coefficient and wear rate during the sliding phase in a 3.5 wt.% NaCl solution against sliding action of Al2O3 ball.