Evolution of hot corrosion resistance of YSZ, Gd_2Zr_2O_7, and Gd_2Zr_2O_7 + YSZ composite thermal barrier coatings in Na_2SO_4 + V_2O_5 at 1050°C

摘要

This paper compares the hot corrosion performance of yttria stabilized zirconia (YSZ), Gd_2Zr_2O_7, and YSZ + Gd_2Zr_2O_7 composite coatings in the presence of molten mixture of Na_2SO_4 + V_2O_5 at 1050 °C. These YSZ and rare earth zirconate coatings were prepared by atmospheric plasma spray (APS). Chemical interaction is found to be the major corrosive mechanism for the deterioration of these coatings. Characterizations using X-ray diffraction (XRD) and scanning electron microscope (SEM) indicate that in the case of YSZ, the reaction between NaVO_3 and Y_2O_3 produces YVO_4 and leads to the transformation of tetragonal ZrO_2 to monoclinic ZrO_2- For the Gd_2Zr_2O_7 + YSZ composite coating, by the formation of GdVO_4, the amount of YVO_4 formed on the YSZ + Gd_2Zr_2O_7 composite coating is significantly reduced. Molten salt also reacts with Gd_2Zr_2O_7 to form GdVO_4. Under a temperature of 1050 °C, Gd_2Zr_2O_7 based coatings are more stable, both thermally and chemically, than YSZ, and exhibit a better hot corrosion resistance. ? 2012 Elsevier Ltd. All rights reserved.