Abstract
ABSTRACTNanoindentation is used to provide a measurement of coating plain strain modulus. The coating properties are then measured by surface acoustic wave spectroscopy (SAWS). It is shown that, by exploiting the relative insensitivity of the SAWS acoustical model to Poisson's ratio, it is possible to measure either the thickness or the density of a thin coating given the input of the other. Furthermore, the indentation and acoustical tests are non-destructive and the resulting value of thickness or density is of high precision. A case study is presented for the measurement of density for a 250 nm thick nano-crystalline Niobium coating on a Si (001) substrate. The density is found to be ρ = 8.4 ± 0.3 g cm−3, about 2 % below bulk values but the modulus is found to be only 85 GPa (for a Poisson's ratio of 0.4), which is 18 % below bulk.
Published Version
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