High-Temperature Corrosion Characteristics of Ni-20Cr-xSi Alloy Laser Cladding Layer in NaCl-KCl-Na2SO4-K2SO4 Mixed Salt Environment

Abstract

Ni-Cr-Si-alloy-cladding layers with Si contents of 0 wt.%, 1 wt.%, 3 wt.% and 5 wt.% were prepared via a laser-cladding technique, and the effect of Si content on the high-temperature corrosion resistance of the Ni-20Cr-Si-alloy-cladding layers in NaCl-KCl-K2SO4-Na2SO4 mixed salt was systematically investigated. The results show that at 600 °C, the four cladding layers rely mainly on the generation of dense Cr2O3 on the surface to hinder the continuation of corrosion. The addition of Si helps to improve the stability of Cr2O3 in the mixed salt, and on the other hand Si is enriched in the corrosion layer, which can effectively hinder the penetration of the corrosive medium. The addition of Si can effectively improve the high-temperature corrosion resistance of the Ni-20Cr-cladding layer, whereas the corrosion product layer is prone to spalling when the Si content is ≥3 wt.%. The best corrosion resistance was demonstrated by Ni-20Cr-1Si in NaCl-KCl-K2SO4-Na2SO4 mixed salt.