Hot corrosion behavior of wire-arc sprayed NiCrB coatings

Abstract

A series of NiCrB coating was deposited using the twin wire arc spraying technique with a newly designed NiCrB (B: 0–4 wt%) cored wire, aiming to protect the boiler tubes used in the waste-to-energy plant. The hot corrosion behavior of the coatings was investigated with the molten salt (Na2SO4 + 10% NaCl, wt%) at 800 °C for 200 h using the thermogravimetric technique. The SEM/EDS and XRD results showed that the addition of element B alleviated the oxidation tendency in the as-deposited coatings. Sufficient free stage Cr atoms diffused to coating surface timely to form protective scale, which inhibited further rapid corrosion, owing to low oxides in the coating. In addition, the corrosion resistance was influenced by the B content of the coating. In the present study, the coating with 1–2% wt% B had the best hot corrosion performance.