(Alcrnbsiti)N/Tin Multilayer Films Designed by a Hybrid Coating System Combining High-Power Impulse Magnetron Sputtering and Cathode Arc Deposition

Abstract

We designed a hybrid coating system equipped with high-power impulse magnetron sputtering (HiPIMS) and cathode arc deposition (CAD) systems to simultaneously achieve high film quality and high deposition rate. With this technique, we fabricated high-performance (AlCrNbSiTi)N/TiN films consisting of alternating layers of (AlCrNbSiTi)N, a high-entropy alloy nitride (HEAN) with high thermal stability and TiN with high hardness. For this sputtering system operating at high deposition rates, a new nucleation and growth model was proposed to explain the thin film deposition phenomenon. Film growth occurred through a self-nucleation mechanism. The effects of the modulation period on the microstructural, mechanical, and oxidation resistance properties of the coatings were investigated using scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, and nanoindentation. All coatings exhibited a B1-NaCl-type face-centered cubic crystal structure. High-resolution TEM imaging revealed misfit dislocations between the HEAN and TiN layers and low-angle boundary dislocations between the subgrains. The 64-layer coating displayed outstanding mechanical, oxidation resistance, and tribological properties compared with those of previously reported multilayer coatings. After oxidation at 800 °C for 2 h in an ambient atmosphere, the plastic deformation index H3/E2 of the mono- and multilayer coatings increased from 0.17 to 0.37 GPa, and the thickness of the oxidation layer decreased from 1228 to 85 nm. Furthermore, the maximum flank wear of a coated tool after milling test was less than that of the uncoated tool (201 vs. 528 µm), suggesting a large improvement in lifetime.

Keywords: High-power impulse magnetron sputtering, High-entropy alloy nitride film, Physical vapor deposition, Self-induced repeated nucleation, Mechanical property, Oxidation resistance