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High-Temperature Corrotion Behavior Of 310SS And It's Protection

Posted on:2003-06-30Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y W ZhangFull Text:PDF
GTID:1101360065456267Subject:Materials science
Abstract/Summary:PDF Full Text Request
Study on the corrosion of structural engineering material in sulfur-containing gas at high-temperature is of considerable industrial importance. Sulfur is an unavoidable contaminant in hot combustion atmospheres derived from coals and other fuels. 310 stainless steel (310SS) is one of the most utilized heat-resistant structural steel used in high-temperature oxidizing environments. In this dissertation, the sulfidation-oxidation of 310SS, effect of powder comment coating and multi-arc ion deposition film on corrosion resistance of 310SS has been investigated, and novel improvement was achieved for 310SS coating.Corrosion data was required in coal inversion system or CS2 furnace for commercial alloys used in sulfur-containing gas. 310SS was therefore decided to study about the sulfidation problem associated with austeuitic stainless steel over a range of sulfur potentials and temperature as a part of the continuing problem on the corrosion of internal component. 310SS running one year in CS2 furnace is worse eroded by pure sulfur vapor. The phase decomposed in crystal boundary of 310SS which running over 10000h at 700C make component Cr in crystal boundary is lack, so intercrystalline corrosion was proceeded because decrease of Cr component.The oxidation-sulfiadation behavior of 31 OSS has been studied in the gas of 0.5%SO2/S2/2.0%N, and 2.3%SO2/S2/8.8%N2 respectively under 1 atm with temperature range of 550-650C . Corrosion rates of 310SS significant enhanced with increasing temperature and VS2/VS02 while, VS2/VS02 content of gas has a slight effect on the corrosion rate. The products of corrosion consisted of three layers: the porous, crisp and dark outer-layer of Fe,.xS, NiO and Fe2O3(small); the compact middle-layer of FeCr2S4 and Cr2O, (small); the inner-layer of NiCr2S4, Cr3S4 containing some Cr2S3, The growth of an outer-layer was generated by out-diffusion of Fe and Ni, while growth of middle-layer and inner-layer was generated by in-diffusion of O and S. The middle-layer was the main factor afferent the diffusion of elements. The kinetics was observed fit with parabolic rate law.High-temperature corrosion resistance of 31 OSS with Aluminizing coating, Borono-Aluminizing coating and Aluminizing after Boronizing coat respectively showed higher than base material, the boronizing coating had little effect on the corrosion resistance of 31 OSS, however, the molybdenumizing treatment significant deteriorated corrosion resistance of 31 OSS.Mo, Nb, Al, Mo-Al and Nb-Al films were deposited on the substrates of 31 OSS respectively through the method of multi-arc ion deposition, and the effects of different procedure parameters (eg. Negative bias voltage, target current and treatment time) on the composition, thickness and quality of film were examined. We studied the high-temperature corrosion behaviors of five sorts samples in the mixture gas of 2.3%SO,/S2/8.8%N2 under 1 atm at 600C. The results indicates that the kinetics of the whole five smples followed parabolic rate. And the sulfldation resistance of the three samples on which were deposited Mo, Nb and Nb-Al films respectively is worse than the substrate, however, the sulfidation resistance of the two samples on which were deposited Al and Mo-Al films respectively is superior to that of substrate. The corrosion mechanism of the worse sample is mainly the appearance of the macroscopic flaws on the corrosive films (eg. cracks and small openings) that accelerates the corrosion process.
Keywords/Search Tags:310 stainless steel (310SS), high-temperature corrosion, oxidation, sulfldation, powder coment coating, multi-arc ion deposition
PDF Full Text Request
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