Investigation of the tribological properties of high-feed milled structures and Cr-based hard PVD-coatings

• Deterministic surface structures are produced by a high-feed milling process.
• The deposition of near-net shaped CrAlN and CrAlCN coatings on surface structures is investigated.
• The friction and the wear resistance can be adapted due to the combination of structures and PVD-coating.
• Cr-based hard coatings in combination with surface structures reduce the adherent material.

Sheet-bulk metal forming is an innovative approach to manufacture complex components which, due to secondary design features, have integrated as well as extended functions. A complex tribological load collective, that has not yet been sufficiently investigated, results from the high degree of deformation, high contact normal stresses of up to 3 GPa with a simultaneously high relative movement of the material, as well as the preference for local adaption of the material flow. Surface structures are a promising approach to locally adapt and control the material flow. Within this context, the present contribution investigates the influence as well as the interdependencies of three high-feed milled deterministic surface structures, combined with Cr-based PVD-hard coatings (CrAlN and CrAlCN), on the friction and wear behavior.The results show that CrAlN as well as CrAlCN-coatings significantly enhance the tribological property profile of the structured surfaces in comparison to hardened ASP2023. Despite the possibility to produce near net-shaped coatings, the wear resistance of the structures is increased by Cr-based hard materials, whereas the uncoated structures are destroyed. All three chosen surface structures show adherent material transfer of the 100Cr6 balls during the sliding contact. Especially the abrasive wear caused by the coated asperities of the structures leads to plowing of the 100Cr6 counter body resulting in debris on the CrAlN and CrAlCN surface.