FAILURE MECHANISMS OF PLASMA-NITRIDED INCONEL-718 FILM

Plasma nitriding was used to form a hard layer containing chromium nit ride to a depth of approximately 7 mu m on Inconel 718. Tribological p roperties of plasma nitrided Inconel 718 specimens were examined using an enclosed pin-on-cylinder unidirectional conformal contact wear tes t apparatus in air and dry nitrogen. Formation of laminar plate-like d ebris after prolonged sliding contact was observed; this debris contai ned fragments of the nitrided layer. The main mechanism that caused th e observed failure of the nitride film is believed to be due to the hi gh local contact stress between the material transferred from the coun terface and the pin specimen. Substitution of air by nitrogen enhanced the formation of wear debris transfer films. (C) 1997 Elsevier Scienc e S.A.