Research On Preparation And Sulfidation Corrosion Of FeCrAl Porous Materials

FeCrAl alloys expected to be new high-temperature structural materials and filter materials for its sulfidation behavior in the corrosive environment. Using powder metallurgy technology the FeCrAl porous materials were prepared, and we made a series of research on the mechanical properties, the porosity and the corrosion performance. The aims on studies of sulfidation behavior of FeCrAl were to analysis and investigate microstructural through various testing methods, understand the essence of sulfidation fully. The sulfidation mechanisms of porous FeCrAl intermetallics in high temperature were discussed in this paper.The sulfidation environment was3%H2S+97%N2at300℃～600℃, within the scope the original sample and pre-oxidation sample of FeCrAl alloy porous materials were researched on. Pre-oxidation processing was carried on in argon gas and air atmosphere before sulfidation. Through the analysis of the oxide film morphology and composition, we proved that the pre-oxidation processing in air atmosphere was the best techniques at non-through pre-oxidation process. Experimental proof for the material pre-oxidation processing can greatly improve the sulfidation of the material. Reference to the mechanism of oxidative, the corrosion mechanism of FeCrAl alloys was done a preliminary inference in H2S+N2atmosphere. At initial stages or low teperature, alloy surface adsorb sulfide gas molecules and generated more dense Al2O3and Al2S3layer, and with good adhesion to matrix. Materials showed a good resistance to sulfide corrosion. As the curing time and the Al elements’ consumption, diffusion plays an increasingly important role and becomes the speed control factors of sulfidation. At this time S through the crack intrudes material interior and Fe element in matrix began to surface enrichment and spread outside. The generated FeS can completely destroy oxidation film and make crystal interface occurrence crackle, then a catastrophic corrosion. For pre-oxidation processing alloy samples, materials showed better antioxidant sulfide corrosion resistance. In this paper the influence of Pre-oxidation to dynamics method, pore diameter variation and shear strength were researched. Hope the experimental data in this paper can be foundation for further study.The research is funded by National "863" Project (Project No.2009AA032601) and finished in Sate Key Laboratory of Porous Metal Materials which relies on Northwest Institute for nonferrous metal research.