Corrosion testing of diffusion-coated steel in molten salt for concentrated solar power tower systems

In this study, the corrosion behavior of coated and uncoated ferritic-martensitic steels of type T91 and VM12 in molten salt (mixture of NaNO3 and KNO3) has been investigated under isothermal conditions. The diffusion coatings are based on potentially protective elements such as Al, Si or Cr and were applied on the steels either by pack cementation or slurry deposition. Characterization of the samples was conducted by means of optical microscope and EPMA in order to gain a deeper understanding of the occurring corrosion mechanisms and for the purpose of lifetime analysis.