KCl-induced corrosion of Ni-based alloys containing 35–45 wt% Cr
Artikel i vetenskaplig tidskrift, 2019

Ni–(35–45)Cr–4Nb alloys containing different fractions of α-Cr were exposed to potassium chloride (KCl)-induced corrosion. The corrosion exposures were carried out for 168 hr at 600°C in a 15% (vol/vol) H2O (g) + 5% (vol/vol) O2 (g) + N2 (g; balance) atmosphere using KCl-free (reference) and predeposited KCl samples. To mimic the KCl deposition in real boilers, 24 hr exposures where KCl vapor condensed continuously onto samples were also performed. The corrosion attack of the studied materials increased significantly when KCl was present compared to the KCl-free samples. For the KCl exposures, the corrosion attack drastically increased when a significant α-Cr fraction was present. α-Cr was either selectively attacked or dissolved through solid-state diffusion and a layered build-up of the outer external scale of K2CrO4 and chromia could be observed. For the in situ condensed KCl exposure, severe corrosion was observed already within the 24 hr exposure, indicating a higher corrosion rate compared with when KCl was predeposited.

selective attack

Ni–Cr–Nb alloys

α-Cr

KCl-induced high-temperature corrosion

phase dissolution

Författare

Yohanes C. Malede

Danmarks Tekniske Universitet (DTU)

Julien Phother Simon

Chalmers, Kemi och kemiteknik, Energi och material, Oorganisk miljökemi

Torbjörn Jonsson

Chalmers, Kemi och kemiteknik, Energi och material, Oorganisk miljökemi

Melanie Montgomery

Danmarks Tekniske Universitet (DTU)

K. V. Dahl

Danmarks Tekniske Universitet (DTU)

John Hald

Danmarks Tekniske Universitet (DTU)

Materials and Corrosion

09475117 (ISSN) 15214176 (eISSN)

Vol. 70 8 1486-1506

Ämneskategorier

Annan kemi

Metallurgi och metalliska material

Korrosionsteknik

DOI

10.1002/maco.201810658

Mer information

Senast uppdaterat

2019-12-02