Growth and characterization of TiAlN/AlN superlattices prepared by reactive magnetron sputtering

Machining of aerospace materials is one of the major challenges of modern manufacturing. Application of nano-multi layered AlTiN/AlN PVD coatings to cemented carbide tooling results in a significant tool life improvement under conditions of cutting hard to machine alloys such as Ni-based Incone l 718 superalloy and Ti-based TiAl6V4 alloy [1]. TiAlN and AlN coatings were prepared using a reactive magnetron sputtering system from TiAl and Al targets. Structural characterization of the coatings using x-ray diffraction (XRD) revealed the B1 NaCl structure of TiAlN with a prominent reflection along the (111) plane and hexagonal wurtizite phase of AlN coatings. Subsequently, nanolayered multilayer coatings of TiAlN/AlN were deposited on silicon and WC-Co substrates at different modulation wavelengths (Λ) with a total thickness of approximately 1.0m. The modulation wavelengths were calculated from the x-ray reflectivity data using modified Bragg’s law. TiAlN/AlN multilayer coatings were textured along (111) for Λ<200 ? Study of thermal stability of the coatings in air indicated that the TiAlN/AlN multilayer coatings were stable up to 900°C in air. TiAlN/AlN multilayer coatings also exhibited improved wear resistance when compared to the substrate.