ISSN:
1573-4889
Keywords:
sulfidation
;
Fe-Cr-Al alloys
;
kinetics
;
structures
;
sulfide compositions
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Sulfidation of an Fe-23.4Cr-18.6Al (at.%) alloy was investigated in H2S-H2 atmospheres, $$10^{ - 6} \leqslant {\text{P}}_{{\text{S}}_{\text{2}} } \leqslant 10^2 $$ Pa, at 973 K. It was found over this pressure range that sulfidation after an early transient period followed the parabolic rate law, being diffusion controlled. An investigation was carried out of the scales formed during early transient sulfidation over the sulfur pressure range $${\text{p}}_{{\text{S}}_{\text{2}} } = 10^{ - 6} - 10^{ - 2} $$ Pa. Fully developed scales were multilayered consisting of an inner compact layer of equiaxed grains, an intermediate layer of equiaxed and columnar grains exhibiting a small degree of porosity, and an outer porous layer of distinct plates and needles. The grains of the inner and intermediate layers contained quarternary sulfide phases. The following phases were identified: spinels (CrFe)Al2S4 and (FeAl)Cr2S4, hexagonal (FeCr)Al2S4, (CrAlFe)2S3, and (CrAlFe)5S6. The plates and needles were composed of hexagonal (FeCr)Al2S4 and (CrAlFe)2S3 at $${\text{p}}_{{\text{S}}_{\text{2}} } \geqslant 10^{ - 6} $$ and 10−5 Pa from which pyrrhotite, FeS, grew at $${\text{p}}_{{\text{S}}_{\text{2}} } \geqslant 10^{ - 4} $$ .
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00665042
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