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J Chin Soc Corr Pro  1990, Vol. 10 Issue (4): 275-286    DOI:
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Na_2SO_4 INDUCED HOT CORROSION OF B- 1900 SUPERALLOY AT INTERMEDIATE TEMPERATURES
Zhang Yunshu Li Lianfang Shih Shengtai (shanghai Institute ot Metallurgy;Acadmia Sinica)
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Abstract  Hot corrosion behavior of Na)2SO_4 coated B-1900 alloy was studied in air at 827 and 750℃.Corrosion kinetics of the coated alloy was gravimetrically measured,and contents of water soluble ions in the reaction products were chemically analyzed.X-ray diffraction and EMP techniques were employed to determine the components and morphology of the corrosion product scale.The experimental results indicate that B-1900 alloy is subject to catastrophic oxidation when covered with Na)2SO_4,and that the hot corrosion is related to the formation of molten Na_2SO_4-Na_2MoO_4-MoO_3 salt on the alloy surface.On the basis of experimental results a corrosion mechanism is proposed for the Na_2SO_4 induced hot corrosion of B-1900 alloy at intermediate temperat- ures.MoO_3(probably as Mo_2O~(2-)_7or Mo_3O~(2-)_(10))is believed to take part in the reduction reaction.The countertransport of MoO_3 and MoO~(2-)_3in the meit carries the reduction reaction of oxygen to the scale (melt)/air interface,which is responsible for the rapid corrosion.The high acidity of the melt and internal sulfidation of the alloy caused by SO_3 resulting from the reaction of Na_2SO_4 with MoO_3 enhance rapid hot corrosion.
Received:  25 August 1990     
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Zhang Yunshu Li Lianfang Shih Shengtai (shanghai Institute ot Metallurgy;Acadmia Sinica). Na_2SO_4 INDUCED HOT CORROSION OF B- 1900 SUPERALLOY AT INTERMEDIATE TEMPERATURES. J Chin Soc Corr Pro, 1990, 10(4): 275-286.

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