IMPERMEABLE THIN Al2O3 OVERLAY FOR TBC PROTECTION FROM SULFATE AND VANADATE ATTACK IN GAS TURBINES

Mao, Scott X.

University of Pittsburgh (United States)

关键词: Vanadates;    Zirconium Oxides;    Sulfates;    Physical Vapor Deposition;    36 Materials Science;   

DOI  :  10.2172/821290
RP-ID  :  NONE
RP-ID  :  FC26-01NT41189
RP-ID  :  821290

美国|英语

来源: UNT Digital Library

【 摘 要 】

In order to improve the hot corrosion resistance of yttria-stabilized zirconia (YSZ), an Al{sub 2}O{sub 3} overlay has been deposited on the surface of YSZ by electron-beam physical vapor deposition. Currently, hot corrosion tests were performed on the YSZ coatings with and without Al{sub 2}O{sub 3} overlay in molten salt mixture (Na{sub 2}SO{sub 4} + 0 {approx} 15wt%V{sub 2}O{sub 5}) at 950 C in order to investigate the effect of amount of vanadate on the hot corrosion behaviors. The results showed that the presence of in V{sub 2}O{sub 5} the molten salt exacerbates the degradation of both the monolithic YSZ coating and the composite YSZ/Al{sub 2}O{sub 3} system. The formation of low-melting Na{sub 2}O-V{sub 2}O{sub 5}-Al{sub 2}O{sub 3} liquid phase is responsible for degradation of the Al{sub 2}O{sub 3} overlay. The Al{sub 2}O{sub 3} overlay acts as a barrier against the infiltration of the molten salt into the YSZ coating during exposure to the molten salt mixture with <5wt% vanadate. In the next reporting period, we will use XPS and SIMS to study the interactions between alumina overlay and molten salt containing vanadate.