Cr diffusion coatings on a ferritic-martensitic steel for corrosion protection in KCl-rich biomass co-firing environments

T.M. Meißner, X. Montero, D. Fähsing, M.C. Galetz

Corrosion Science (2019), DOI: 10.1016/j.corsci.2019.108343

Three diffusion coatings (Cr, Ni + Cr, Ni-P + Cr) on a ferritic-martensitic X20CrMoV12-1 steel were investigated in a biomass-co-firing atmosphere in comparison to uncoated austenitic DMV 310 N. Exposures were conducted at 650 °C for up to 300 h with pure sulphates as well as a mixture of sulphates and KCl. These aggressive testing conditions were chosen to accelerate degradation of the specimens allowing for an efficient ranking between them. Beneath the deposit of Na2SO4-K2SO4 the coatings proved to be highly resistant whereas addition of KCl drastically accelerated the corrosive attack. This is discussed within the frame of different synergistic high temperature corrosion mechanisms.

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