Material Corrosion Investigations for Urea SCR Diesel Exhaust Systems

Floyd, Ryan; Kotrba, Adam; Martin, Scott M.; Prodin, Keith

doi:10.4271/2009-01-2883

Cited by 7 publications

(1 citation statement)

References 10 publications

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“…However, more generally, it is concluded that the cracking and fracturing of metal is related to urea decomposition products and intergranular attack [2,4,[14][15][16][17][18]. By many scientists, an intergranular corrosion mechanism, sometimes attributed to chromium depletion, and nitride precipitation at grain boundaries, and sometimes without any indication of decrease or increase in the amount of chromium at grain boundaries, was described [4,19,20].…”

Section: Introductionmentioning

confidence: 99%

Corrosion of Stainless Steel by Urea at High Temperature

Galakhova

Kadisch²,

Mori³

et al. 2021

CMD

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The corrosion mechanism of stainless steel caused by high temperature decomposition of aqueous urea solution has been investigated. The relationship between aqueous urea solution, its thermal decomposition products and the corrosion mechanism of stainless steel is studied by FTIR spectroscopy, SEM and stereo microscopy. The corroded steel samples, together with deposits, were obtained from the injection of aqueous urea solution on the steel plate at high temperatures. Uniform corrosion underneath the deposits was proposed as the main driver for corrosion of the steel samples. At the crevices, corrosion due to the used geometry and due to high temperature cycling could play an acceleration role as well.

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Section: Introductionmentioning

confidence: 99%

Corrosion of Stainless Steel by Urea at High Temperature

Galakhova

Kadisch²,

Mori³

et al. 2021

CMD

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Corrosion of stainless steels in simulated diesel exhaust environment with urea

Nockert

Nyborg

Norell

2011

Materials & Corrosion

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Laboratory exposures have been performed simulating a selective catalytic reduction (SCR) system with urea injection for NOx reduction in diesel exhaust after‐treatment. The corrosion behaviour of three ferritic and one austenitic stainless steel was examined using X‐ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Continuous exposure to condensate did not cause any corrosion. Results show that cyclic interaction between high temperature and condensation aggravates the corrosion compared to isothermal exposure at 450 °C. All ferritic alloys exhibited more or less the same behaviour, while the austenitic steel performed better. In fact, the presence of urea decreased the corrosion compared to the environment without urea. The cyclic samples exposed with urea displayed iron sulphate on the surface. The sulphate appeared to decrease the oxide thickness. A sulphur enrichment in the form of sulphide also occurred in the inner chromium‐rich oxides of all cyclically exposed samples, both with and without urea. Thus, sulphidation is presumed to be involved in the corrosion process.

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