Hot corrosion behaviour of 7YSZ + Gd₂O₃ nano-composites in molten salts prepared by spark plasma sintering

Abstract

This study compares the hot corrosion performance of yttria-stabilised zirconia (7YSZ), and 7YSZ + Gd 2 O 3 composite samples in the presence of molten mixture of Na 2 SO 4 + V 2 O 5 at 1150°C. For 7YSZ, the reaction between NaVO 3 and Y 2 O 3 produces YVO 4 and leads the transformation of tetragonal ZrO 2 to monoclinic ZrO 2 . A high-density in sintered 7YSZ + Gd 2 O 3 samples, led minor amounts of monoclinic ZrO 2 and tetragonal GdVO 4 as the hot corrosion products with only traceable amounts of YVO 4 , and a stable corroded layer was formed. Due to the synergic effect of doping of zirconia with Gd 2 O 3 , the 7YSZ + Gd 2 O 3 sample has a much better hot corrosion crack resistance than 7YSZ.