| Rare-earth doped YSZ coating can be applied to thermal barrier coatings (TBCs). The ability of luminescence of rare earth elements can be used to detect real-time temperature of TBCs. Correspondingly, the reliability of TBCs can be monitored, and further the service life of the coating can be evaluated. YSZ powder doped with Rare-earth was prepared using the chemical precipitation method in this study. Both YSZ:Tm and YSZ:(Tm,Dy) powder, made by this method have favourable luminescent properties and phase stability, and is feasible for plasma spraying. Coatings were prepared by atmospheric plasma spraying. Microstructure and Luminescent Properties of coatings, sprayed at different spraying powers and different spraying distances were studied. In addition, the effect of loading force, high-temperature calcinations and overlying coating thickness on the microstructure and luminescent behavior of YSZ:(Tm, Dy) coatings were investigated.Yttria powders can solid solute into the doped powders completely with the increases in the mother liquor concentration, and also in the aging time. Additionally, the calcination temperature affected the crystalline phase of powders obviously.Reasonable doping concentration of rare earth elements has no influence on the phase composition of YSZ coating when Tm and Dy are doped into. In addition, the phase composition of coatings keeps invariable when the spraying distance and power are changed in the present range. The porosity of coatings increases with increasing spraying distance, and correspondingly the luminous intensity of coatings decreases. The changing tendency of porosity and luminance intensity of coatings on the spraying power is similar to those on the spraying distance. The luminous intensity of coatings can be affected by the high-temperature calcinations, overlying coating thickness and external loading. The luminous signal can be detected even though the intensity decreases compared to those with no additional treatments. |
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