Fig. 9 shows the XRD results of the conventional YSZ and the laser clad coating after hot corrosion test. Pattern (a) belongs to the conventional YSZ. It is obvious from this pattern that after hot corrosion test, the conventional YSZ contains phases such a t′-ZrO2 m-ZrO2 and YVO4 (rod shaped crystals in Fig. 8). Peaks of, m-ZrO2 and YVO4 (as corrosion products) are so sharp in this pattern which is indicative of the low hot corrosion resistance of the coating. Pattern (b) is the XRD analysis of the laser clad coating after the hot corrosion test. The corrosion products are also pre- sent in this pattern, however, the peaks in the pattern of laser clad coating are shortened which indicates the improved hot corrosion resistance of the TBC after laser cladding. the peak intensity of YVO4 before laser cladding is almost 2 times of peak intensity after laser cladding. It was mentioned earlier that during reactions be- tween yttria and the molten salts, yttria will be leached out from the YSZ, resulting in destabilization of the t′-ZrO2 and formation of the m-ZrO2. This transformation is accompanied by a large de- structive volume change [5]. The stresses resulting from the vo- lume change cause the delamination and spalling of the coating.