Stabilization of cubic phase in AlTiN coatings using anode configurations

• This paper describes methods to produce hard AlTiN coatings with low stress.
• Effect of bias voltage on coating stress and delamination is confirmed by experimental studies.
• Anode configuration described stabilizes the cubic AlTiN phase.
• Stabilization of AlTiN phase dissociates effect of bias from the stress and enables thick coatings without delamination.

In this study, the effects of residual stress and hardness in view of producing thick PVD AlTiN coatings are investigated. The compressive residual stress in the coatings results in coating delamination at the cutting edges. Coatings produced at lower stress overcome the delamination issue, however lack the required hardness for metal cutting applications. We found that reduction in hardness is closely related to stability of cubic AlTiN phase. We present an anode configuration ‘annular extension’ to stabilize cubic phase and produce thick PVD coatings. The usefulness and limitations of thick PVD coatings are also discussed.