Investigation of reactions between vanadium oxide and plasma-sprayed yttria-stabilized zirconia coatings

✍ Scribed by Zun Chen; Scott Speakman; Jane Howe; Hsin Wang; Wally Porter; Rodney Trice

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 845 KB
• Volume: 29
• Category: Article
• ISSN: 0955-2219
• DOI: 10.1016/j.jeurceramsoc.2008.09.016

✦ Synopsis

The phase evolution occurring during the reaction between corrosive V 2 O 5 (T m = 690 • C) and a plasma-sprayed 7 wt.% Y 2 O 3 -ZrO 2 (YSZ) coating from 700 to 900 • C has been investigated in situ by X-ray diffraction. The temperature and time of interaction between the V 2 O 5 and YSZ coating determines the phases observed. Between 700 and 750 • C, reaction products of ZrV 2 O 7 and YVO 4 were observed within minutes of reaching the test temperature. m-ZrO 2 was observed after 220 and 60 min at 700 and 750 • C, respectively. The simultaneous formation of both ZrV 2 O 7 and YVO 4 at the beginning of the reaction along with the delay of the m-ZrO 2 formation suggests similar reactivity between both Zr and Y with V 2 O 5 . The weight percent of the ZrV 2 O 7 phase began to diminish after 150 and 60 min at 700 and 750 • C, respectively. For reaction temperatures of 800 and 900 • C, there is a rapid decrease in the amount of t -ZrO 2 and a rapid increase in the amount of m-ZrO 2 with reaction time. YVO 4 was also observed at these reaction temperatures. SEM and TEM microstructural observations confirmed the phases detected from the in situ XRD experiments. Reactions between YSZ and V 2 O 5 suggest that the formation of a liquid phase due to the high solubility of both zirconia and yttria in vanadia is the dominate mechanism that damages the coating. The thermal conductivity of a plasma-sprayed YSZ coating reacted with up to 1 wt.% V 2 O 5 did not significantly change due to the small volume affected.