Thermal sprayed coatings characterization by acoustic waves

For improving the thermal spray technologies of protective coatings, it is necessary to measure their elastic properties. Non-destructive evaluation of the coatings by ultrasonic techniques in an inversion procedure seems to be a suitable technique to perform such a measurement. However, inversion procedures usually require considerable computational efforts. It is thus desired to identify procedures which will enable these properties to be decoupled so they can be evaluated independently, one at a time. It has been found that for a composite consisting of an isotropic substrate coated by an anisotropic film (6 mm symmetry), the sagittal plane components of the acoustic fields can be separated from the SH component. This paper presents several useful formulae which have been derived to relate some of the coatings elastic components to critical values in SH modes measurements.