97 0

Corrosion behavior of Hastelloy (R) C-4 (R) Ni-Cr-Mo-Fe alloys for coal gasification syngas plants

Title
Corrosion behavior of Hastelloy (R) C-4 (R) Ni-Cr-Mo-Fe alloys for coal gasification syngas plants
Author
박주현
Keywords
Mixed oxidant corrosion; Hastelloy (R) C-4; coal gasification; synthetic gas (syngas); high temperature corrosion; hydrated chlorides; halogen corrosion of metals
Issue Date
2018-02
Publisher
CARL HANSER VERLAG
Citation
MATERIALS TESTING, v. 60, No. 2, Page. 156-162
Abstract
A mechanistic exposure experiment was performed on welded samples of the commercially available Haynes (R) Hastelloy (R) C-4 (R) Ni-Cr-Mo-Fe alloy (65 wt.-% Ni, 16 wt.-% Cr, 16 wt.-% Mo, 3 wt.-% Fe, 2 wt.-% Co, 1 wt.-% Mn, 0.7 wt.-% Ti, 0.5 wt.-% Cu, 0.08 wt.-% Si and 0.01 wt.-% C) at coal gasification pilot plant facilities affiliated with the Institute for Advanced Engineering in Yongin-si, South Korea. The alloy samples were preoxidized at 400 degrees C under a stagnant air atmosphere for 24 h prior to exposure to the corrosive environment (60 % CO, 28.4 % H-2, 2.5 % CO2, 0.8 % CH4, 600 ppm H2S and 110 ppm carbonyl sulfide under 2.005 MPa pressure and 170 degrees C). Thermodynamic Ellingham-Pourbaix stability diagrams were constructed to provide insight into the mechanism of the observed corrosion behavior prevailing in the piping materials between the particulate removal unit and water scrubber of the coal gasification pilot plant. The thermodynamic inference of the corrosion mechanism was supplemented with morphological, compositional and microstructural analyses of the exposed samples using scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy analyses performed on the external and cross-sectional surfaces of the recovered corrosion test samples to comprehensively examine the corrosion scale. The X-ray diffraction results revealed stable corrosion products of NiO, MoNi4 and Cr4.6MoNi2.1 after a total accumulated exposure duration of 139 h to the corrosive atmosphere. Scanning electron microscopy and energy dispersive X-ray spectroscopy positively identified the formation of rather continuous and adherent preoxidation corrosion products in the alloy samples, although extensively peeled off oxides were eventually observed as corrosion scale on the post-exposure alloy samples, which were attributed to the combined effects of the evaporation of the hydrated Fe, Al and Cr chlorides and their subsequent transformation into thin (spalled) oxides.
URI
https://www.hanser-elibrary.com/doi/abs/10.3139/120.111137https://repository.hanyang.ac.kr/handle/20.500.11754/121351
ISSN
0025-5300
DOI
10.3139/120.111137
Appears in Collections:
COLLEGE OF ENGINEERING SCIENCES[E](공학대학) > MATERIALS SCIENCE AND CHEMICAL ENGINEERING(재료화학공학과) > Articles
Files in This Item:
There are no files associated with this item.
Export
RIS (EndNote)
XLS (Excel)
XML


qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE