Cathodic arc evaporation of (Ti,AI)N coatings and (Ti,AI)N/TiN multilayer-coatings-correlation between lifetime of coated cutting tools, structural and mechanical film properties

(Ti,Al)N and (TiAl)N/TiN multi-layer coatings were deposited by cathodic arc evaporation with a large area TiAl and/or Ti cathode. The ratio of Ti/Al varied between 50/50, 40/60 and 33/61. The goal was to determine the influence of the bias voltage, which varied between -30 and -125 V, on the lifetime of coated cutting tools under drilling conditions. Film orientation and compressive stress were determined by X-ray diffraction. The chemical composition of the coatings was investigated by secondary-neutral-mass spectrometry (SNMS). It was found, that in the multi-layer coatings, there is a transition in the texture from (2 0 0) to (1 0 0) with increasing negative bias voltage, beginning at approximately -75 V, while the monolayer retained (2 0 0) orientation. The stress in the monolayers reached a maximum at a bias voltage approximately -100 V. Rockwell and Scratch tests show excellent adhesion on carbide and steel materials. Multilayer tool lifetime reached a maximum at -100 V, while the monolayer coated tool life increased monotonically with negative bias. (C) 2003 Elsevier B.V. All rights reserved.