Substrate temperature: A governing factor for the structural, mechanical and chemical properties of sputtered CrAlN ternary coating

Abstract

In this article, the effect of substrate temperature towards the structural, microstructural and mechanical properties of the Chromium-Aluminium-Nitride (CrAlN) films deposited on Si (100) and SS-304 substrates by Radio frequency magnetron sputtering was investigated. Different characterization techniques like Grazing Incidence X-Ray Diffraction (GIXRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-Ray Spectroscopy (EDS), Nanoindentation, etc. were carried out for establishing structural-mechanical property relationship. From GIXRD analysis, it was confirmed that the films exhibited FCC NaCl type structure with primary orientation along (200) direction. The grain size is in slightly increasing order till 300 degrees C and then it decreased, reaching the lowest value for the film deposited at 500 degrees C. After finding the ideal load for hardness measurement using load-variation analysis in nanoindentation, the hardness and elastic modulus measurements were carried out. The coating deposited at 400 degrees C showed the best mechanical properties having hardness and elastic modulus values of 22.97 +/- 0.47 GPa and 218.72 +/- 2.24 GPa respectively. The coating also showed a high elastic recovery of 69.42%, suggesting the possibility of numerous industrial applications of CrAlN coating. High corrosion resistance indicating better chemical stability in all coatings was observed, when corrosion measurements were carried out in 3.5% NaCl solution.