Kinetics and Mechanism of Hot Corrosion of -Y2Si2O7 in Thin-Film Na2SO4 Molten Salt
Abstract:-Y2Si2O7 is a promising candidate material both for high-temperature structural applications and as an environmental/thermal barrier coating material due to its unique properties such as high melting point, machinability, thermal stability, low linear thermal expansion coefficient (3.9 × 10−6/K, 200°–1300°C), and low thermal conductivity (<3.0 W/m·K above 300°C). The hot corrosion behavior of -Y2Si2O7 in thin-film molten Na2SO4 at 850°–1000°C for 20 h in flowing air was investigated using a thermogravimetric analyzer (TGA) and a mass spectrometer (MS). -Y2Si2O7 exhibited good resistance against Na2SO4 molten salt. The kinetic curves were well fitted by a paralinear equation: the linear part was caused by the evaporation of Na2SO4 and the parabolic part came from gas products evolved from the hotcorrosion reaction. A thin silica film formed under the corrosion scale was the key factor for retarding the hot corrosion. The apparent activation energy for the corrosion of -Y2Si2O7 in Na2SO4 molten salt with flowing air was evaluated to be 255 kJ/mol.
Document Type: Research Article
Affiliations: Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
Publication date: 2008-07-01