TiAlCN/VCN nanolayer coatings suitable for machining of Al and Ti alloys deposited by combined high power impulse magnetron sputtering/unbalanced magnetron sputtering

Abstract

Nanoscale multilayer TiAlCN/VCN coatings with bilayer thickness Δ=2·2 nm were deposited by the combined high power impulse magnetron sputtering (HIPIMS)/unbalanced magnetron sputtering technology. The V⁺ HIPIMS etching produced atomically clean interface and V implantation resulting in enhanced coating adhesion L_C=58 N. High resolution transmission electron microscopy and electron energy loss spectroscopy revealed that in TiAlCN/VCN, carbon forms a lateral phase between the nanolayers, producing low shear strength interfaces. This results in a well defined nanometre scale layer by layer wear mechanism, which is the key for prevention of tribofilm and consequently thick built up layer formation. In dry milling of Al 7010-T 7651 alloy, TiAlCN/VCN outperformed state of the art diamond like carbon, Cr/WC/a-CH coated and uncoated end mills by factors of 4 and 8 respectively. In turning of Ti alloys (Ti_0·90Al_0·06V_0·04) the TiAlCN/VCN coated cemented carbide inserts produced two to three times more components (orthopaedic implants), as compared to uncoated tools.