Tribological response of AA 2024-T3 aluminium alloy coated with a DLC duplex coating

Abstract

Considerable improvement in the tribological response was achieved during sliding wear tests against alumina ball, when AA 2024-T3-aluminium alloy substrate was coated with DLC/NiP duplex coating. Quantitative EPMA analysis carried out on the coated sample cross-section coupled with nanoindentation techniques allowed the identification of the coated system architecture as composed of 4 main layers, with distinct mechanical properties, on top of the aluminium substrate: DLC (a:C-H chromium dopped layer and graded layer of CrC), a newly formed graded layer of CNiPCr, product of the interdifusion during PVD processing, and the NiP coating. The change in the elastic modulus with penetration depth was described by means of an original approach that was developed for its specific application to multilayer coatings.