An enhanced formulation to determine Young's and shear moduli of thin films by means of Impulse Excitation Technique

This work presents an enhanced approach to determine the Young's and shear moduli and Poisson's ratio of coatings by means of the Impulse Excitation Technique. The proposed relation takes into account the shift of the neutral axis after deposition, which makes it applicable for any film thickness. The proposed analytical expression was established thanks to the application of the Hamilton's principle allowing the determination of the warping function of the composite system and therefore its torsional resonant frequency. It was applied to determine the macroscopic elasticity constants of tungsten films deposited on glass substrates by conventional magnetron sputtering. Moreover, in order to discuss the values of shear and Young's moduli, the films structure and morphology were also analyzed by X-ray diffraction and scanning electron microscopy.