Corrosion of nickel and nickel–phosphorous-coated AISI 430 in dry (Ar–3%H2) and humid hydrogen (Ar–3%H2–3%H2O) atmosphere

Abstract

The corrosion behavior of uncoated, nickel (Ni) and nickel-phosphorous (Ni-P)-coated AISI 430 alloy was investigated in Ar-3%H 2 and Ar-3%H 2 -3%H 2 O atmosphere at 800°C for 100 h. Microstructure, chemical composition, and reaction products were analyzed by scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction techniques. The corrosion extent of Ni-P-coated AISI 430 is higher than Nicoated AISI 430. Oxidation promotes corrosion in the uncoated and coated alloy. The oxidation rate of Ni-coated alloy is the lowest in Ar-3%H 2 but Ni-P-coated alloy in Ar-3%H 2 -3%H 2 O for initial 20 h. The oxidation rate of the Ni-P-coated sample is ∼14 times higher in 20-100 h in Ar-3%H 2 -3%H 2 O. External growth of Cr 2 O 3 is observed for Ni-coated alloy in Ar-3%H 2 and for Ni-P-coated alloy in both the atmospheres. Inward growth of Cr 2 O 3 by AISI 430 alloy consumption attributes to the lowest oxidation rate and the corrosion extent of Ni-coated sample in Ar-3%H 2 -3%H 2 O.