High temperature corrosion of Fe-Cr-Mn-alloys in H2-H2S and H2-H2O-H2S gas mixtures
1985; Wiley; Volume: 36; Issue: 7 Linguagem: Inglês
10.1002/maco.19850360704
ISSN1521-4176
AutoresP. Papaiacovou, Hans Jürgen Grabke, Péter Schmidt,
Tópico(s)Metal Alloys Wear and Properties
ResumoAbstract The sulfidation of Fe‐20% Cr‐30% Mn, Fe‐25%Cr‐20%Mn and Fe‐25% Cr was studied at 700°C in H 2 ‐H 2 S and the oxidation and sulfidation in H 2 ‐H 2 O‐H 2 S after preoxidation in H 2 ‐H 2 O. The sulfidation rate is strongly increased for the Mn‐containing alloys, layers of (Mn,Cr)S and (Mn,Fe)Cr 2 S 4 are formed. Also the oxidation rate is enhanced compared to Fe‐25% Cr by formation of MnCr 2 O 4 instead of Cr 2 O 3 . The sulfidation after preoxidation leads to internal and external sulfidation of the Mn‐containing alloys. With increasing oxygen pressure p(O 2 ) = 10 −26 …10 −22 atm. of the H 2 ‐H 2 O‐H 2 S mixtures the sulfidation is suppressed, for the higher oxygen pressure 10 −23 and 10 −22 atm. fast oxidation prevails under formation of MnCr 2 O 4 . Manganese cannot increase the sulfidation resistance of alloys, in spite of the stability and low degree of disorder of its sulfide, since the mixed sulfide (Mn,Cr)S is formed which has a high degree of disorder, high diffusivities and high growth rate according to the doping effect of trivalent Cr 3+ .
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