Kinetics and mechanism of hot corrosion of y-Y2Si2O7 in thin-film Na2SO4 molten salt



Publication Details

Sun, Z., Li, M.& Zhou, Y.(2008).Kinetics and mechanism of hot corrosion of y-Y2Si2O7 in thin-film Na2SO4 molten salt.Journal of the American Ceramic Society, 91 (7), 2236-2242.


gamma-Y(2)Si(2)O(7) 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 x 10(-6)/K, 200 degrees-1300 degrees C), and low thermal conductivity (< 3.0 W/m.K above 300 degrees C).The hot corrosion behavior of gamma-Y(2)Si(2)O(7) in thin-film molten Na(2)SO(4) at 850 degrees-1000 degrees C for 20 h in flowing air was investigated using a thermogravimetric analyzer (TGA) and a mass spectrometer (MS).gamma-Y(2)Si(2)O(7) exhibited good resistance against Na(2)SO(4) molten salt.The kinetic curves were well fitted by a paralinear equation: the linear part was caused by the evaporation of Na(2)SO(4) 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 gamma-Y(2)Si(2)O(7) in Na(2)SO(4) molten salt with flowing air was evaluated to be 255 kJ/mol.

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