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Influence of H 2 S on metal dusting
Author(s) -
Schneider A.,
Viefhaus H.,
Inden G.,
Grabke H. J.,
MüllerLorenz E. M.
Publication year - 1998
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/(sici)1521-4176(199805)49:5<336::aid-maco336>3.0.co;2-1
Subject(s) - metal , cementite , carbide , chemistry , kinetics , graphite , nucleation , carburizing , carbon fibers , metallurgy , materials science , austenite , composite material , organic chemistry , microstructure , physics , quantum mechanics , composite number
Presence of H 2 S in a carburizing atmosphere causes S‐adsorption which retards carbon transfer and deposition and can suppress metal dusting of iron and steels. In the latter process cementite Fe 3 C is an intermediate, graphite deposition would initiate its decomposition but graphite nucleation is prevented by adsorbed sulfur. Thus continued Fe 3 C growth can be observed in the presence of H 2 S. Thermogravimetric studies in CO‐H 2 ‐H 2 O‐H 2 S mixtures have been conducted at 500°C at various carbon activities a C and H 2 S/H 2 ‐ratios. With increasing a C higher H 2 S/H 2 ‐ratios are needed to suppress metal dusting, with increasing H 2 S/H 2 ‐ratio the kinetics of Fe 3 C growth change from diffusion controlled parabolic kinetics to linear carbon transfer controlled kinetics. At very high a C ≥1000 besides Fe 3 C also the Hägg carbide Fe 5 C2 was observed as an outer layer on the cementite.