Corrosion Protection of Boiler Components Using an Arc Sprayed Cladding Material

An arc sprayed NiCrB alloy cladding material (AmStar888) was used to protect fossil-fired and waste-to-energy boiler components from fireside corrosion. Laboratory tests were conducted on this material to evaluate its corrosion performance. The tests included pyritic decomposition, oxidation, cyclic oxidation and sulfidation, and salt permeability. The results of these tests are discussed in this article. Field testing was also performed on AmStar888 cladding and the results show that the cladding mitigated corrosion and circumferential cracking on both carbon steel and low alloy ferritic tubing. Furthermore, optical microscopy, SEM/EDAX and X-ray mapping techniques were used to characterize the cladding, and the corrosion products within the cladding. The characterization studies showed that the corrosion products were formed along the cladding splat boundaries and acted as a sealant, which prevented corrosion species from permeating to the base material. Also, the study showed that the cladding was intact and bonded well to the base material.