EVALUATION OF THE RESIDUAL STRESSES IN ADVANCED COMPOSITE CERAMIC COATINGS USING X-RAY DIFFRACTION TECHNIQUES
X-Rays diffraction method were used to determine the residual stresses and local phase composition through the thickness of as-sprayed by flame-sprayed thermal barrier coatings consisting of a NiAl bond coat and composite ceramic coatings (Al2O3 –22wt% ZrSiO4) topcoat produced. The as-sprayed residual stresses reflected the combined influence of quenching stresses from the flame spray process, thermal expansion mismatch between the topcoat, bond coat and substrate, and stress relief from the segmentation cracks. The thickness of bond coating was (150ϻm) and for composite ceramic coating was (450 ϻm). The residual stresses evaluated by X-Ray diffraction technique were maximum tensile residual stresses (15.626) Mpa.