Evaluation of structural and mechanical properties of CrAlN single layer coating deposited by reactive magnetron sputtering

The objective of this study is to evaluate the structural and mechanical properties of CrAlN coating obtained by reactive RF magnetron sputtering with (Cr0.5Al0.5) alloy targets in a mixed atmosphere of Argon–Nitrogen (Ar:N2). During deposition, the RF power and substrate temperature were fixed at 120 W and 300 °C, respectively. The Ar: N2 contents were varied at different ratios like 20:2, 20:4, 20:6, 20:8 and 20:10. Grazing Incidence X-ray Diffraction (GIXRD) study was performed to identify the phases present in the coating. The surface morphology and mechanical properties were studied using Field Emission Scanning Electron Microscopy (FESEM) and Nanoindentation, respectively. GIXRD shows the presence of a dominant Face Centered Cubic (FCC) CrN phase. Plane view and cross-sectional FESEM micrographs presented the different Ar:N2 ratios-dependent changes in the microstructures. The CrAlN coating deposited at Ar:N2 contents of 20:6 shows maximum elastic modulus and hardness value compared to other coatings. In our studies, the maximum hardness (H), elastic modulus (Er), elastic recovery (We), and resistance to plastic deformation (H3/E2) were obtained to be 22.96 GPa, 225.79 GPa, 74.81%, and 273 MPa respectively for 20:6 CrAlN deposited coating. This study also shows that different Ar:N2 ratio strongly affects the crystalline microstructure and mechanical properties of the deposited coatings.