Corrosion of nickel and nickel-phosphorous-coated AISI 430 in dry (Ar-3%H_2) and humid hydrogen (Ar-3%H_2-3%H_2O) atmosphere

摘要

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_2O 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 Ni-coated 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_2O 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_2O. External growth of Cr_2O_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_2O_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_2O.