Experimental Investigation of Displacement/Strain Fields in Metal Coatings Deposited on Ceramic Substrates by Thermal Spraying

The paper presents the initial results of application of the high sensitivity grating interferometry (GI) method in order to measure the displacement and strain fields in copper and titanium coatings thermally sprayed onto alumina ceramic (Al2O3). The residual stresses had been relieved by iterative cutting method, which was applied twice. The displacement maps of u and v were measured after each cut and exx and eyy maps were calculated. The results clearly show the presence of exx strains relieved along the second cut. The comparison of both samples confirmed that residual strains in Ti/Al2O3 are more significant than in Cu/Al2O3 system. The result after relevant postprocessing had been supplemented with the sub-surface principal residual stresses measured in the selected point by the x-ray diffraction method and curvature measurements.