Sliding wear behavior of duplex coatings with different plasma nitride layers and a Cr‐Al‐Ti‐B‐N coating

Abstract

AbstractThe dry sliding wear behavior of AISI D2 tool steel is investigated under different heat treatment states in hardened, plasma nitrided, and duplex layer conditions. Plasma nitriding (PN) is performed at 510–520°C with varying N2‐H2 gas mixtures, and Cr‐Al‐Ti‐B‐N layers are deposited at 480°C by means of physical vapor deposition (PVD). This work investigates the influence of the nitride layer and, in particular, the presence of a compound layer on the tribological behavior of the duplex layer system. Therefore, as‐nitrided conditions both without and with a compound layer – as well as with a mechanically removed compound layer – are subsequently hard coated. Comparative ball‐on‐disc wear tests in linear‐reciprocating sliding motion against WC‐Co counterbody balls are conducted at a load of 120 N. Compared to sample states without a compound layer, the as‐nitrided states with a compound layer exhibit improved wear coefficients. In contrast, all duplex layer states exhibit comparably low friction coefficients and low wear coefficients independently of the presence of a compound layer. Removal of the compound layer prior to PVD coating leads to a significant reduction in wear resistance due to reduced surface roughness before the hard coating and the associated change in the bonding between the nitride layer and hard coating.