Effect of interlayer design on the mechanical properties of AlTiCrN and multilayered AlTiCrN/TiSiN hard coatings

The adhesion strength and mechanical properties of hard coatings on substrates can be improved by adding an interlayer, which is also known as an adhesion, buffer, or seed layer. Cathodic-arc deposition (CAD) of hard coating often results in residual stresses, and the optimized design of the hard coating interlayer helps to reduce residual stress and improve mechanical properties, which is expected to extend the useful life of high speed precision stamping die applications. AlTiCrN transition metal nitride has been used as a protective hard coating because of its high hardness (similar to 36 GPa) and resistance to high temperature oxidation up to 1100 degrees C. In this study, multicomponent hard coatings of AlTiCrN and AlTiCrN/TiSiN, which in the form of AlTiCrN/TiSiN multilayers, were deposited by cathodic-arc deposition. During the coating process, gradient TiN and CrN were deposited, respectively, as interlayers with different structures to control the residual stress and adhesion strength between the coatings and substrates. AlTiCr and TiSi alloy targets were used to deposit hard AlTiCrN/TiSiN coatings. The multicomponent AlTiCrN/Ti and AlTiCrN/Cr with Ti and Cr interlayers showed high residual stresses of -8 GPa and -8.4 GPa, respectively. The multilayered AlTiCrN/TiSiN coating with intermediate CrN and transition AlTiN/CrN multilayers under the top AlTiCrN/TiSiN multilayers possessed the lowest residual stress (-3 GPa). The residual stress changed by modifying interlayer configuration before the top AlTiCrN/TiSiN multilayers. The design of AlTiCrN/TiSiN multilayered coatings with interlayers of CrN and AlTiCrN/CrN can decrease residual stress and possessed good impact fatigue performance, which can be effective to reduce damage and cracking of hard coatings during cyclic impact loading.