Features of self-organization in ion modified nanocrystalline plasma vapor deposited AlTiN coatings under severe tribological conditions

Abstract

Features of self-organization in the hard AlTiN plasma vapor deposited (PVD) coatings have been investigated under severe frictional conditions associated with high temperatures and stresses, which are typical for high-speed cutting. Aluminum-rich (around 67at.%) (Al67Ti33)N hard PVD coating has been modified by means of the “duplex” post-treatment, including annealing in vacuum at 700°C with subsequent ion implantation by Ar+. Structure modification of the surface layer has been studied using x-ray photoelectron spectroscopy, electron energy loss fine structure, and high resolution electron energy loss spectroscopy methods. Micromechanical characteristics of the coating have been studied using the nanoindentation method. Coefficient of friction was measured in relation to temperature. Wear behavior of the coating has been investigated under severe conditions of HSC of 1040 steel. Results show that the enhancement of nonequilibrium processes during friction due to ion implantation of AlTiN coating by Ar+ leads to a dominating formation of protective triboceramics on the surface with sapphire-like structure that critically improves wear performance. Analytical modeling of the mass transfer within initial stage of wear was performed based on the concept of irreversible thermodynamics and self-organization in order to formulate the principles of friction control.