Oxidation of electroless Ni–P coated AISI 430 alloy and effect of pre-reduction

Abstract

The oxidation behavior of electroless Ni-P coated AISI 430 alloy was investigated at 800 °C in moisture-saturated (~ 3% H 2 O) air. Effect of pre-reduction in dry hydrogen (Ar-3%H 2 ) at 800 °C on the oxidation behavior of the Ni-P coated AISI 430 was also studied. Microstructure, chemical composition, and compound/oxide phase formation across the oxide layer were analyzed by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction techniques. Iron oxide Fe 2 NiO 4 spinel along with other oxide and spinel phases are found in the multilayered oxide scale for both the Ni-P coated and pre-reduced Ni-P coated AISI 430 alloy. Ni-P coating crystallization and oxidation initiates the oxidation for the electroless sample. Ni 3 P and FeNi 3 intermetallic compounds formed during reduction initiates the oxidation of the pre-reduced sample.

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

“…1(c)-1(f). Oxidation rate in air-3% H 2 O [22,24] is also shown for comparison. Faster oxidation rate is observed in the initial 20 h except for the Ni-P-coated sample [Fig.…”

“…For example, pores/voids and cracks at the oxide scale can compromise thermo-mechanical integrity due to spallation of oxide scale. Ni-P coating, widely used for corrosion protection of steel, also improves the oxidation resistance of ferritic alloy in humidified air [24]. Significant porosity in the oxide scale is found for Ni-P-coated AISI 430 alloy [24] while negligible for nickel coating [22].…”

“…Ni-P coating, widely used for corrosion protection of steel, also improves the oxidation resistance of ferritic alloy in humidified air [24]. Significant porosity in the oxide scale is found for Ni-P-coated AISI 430 alloy [24] while negligible for nickel coating [22]. We have investigated the corrosion of ∼5 μm thick nickel and Ni-P-coated AISI 430 alloy, a commercial ferritic alloy with similar properties of specialized Crofer 22 APU and AISI 441, in dry (Ar-3% H 2 ) and humidified hydrogen (Ar-3% H 2 -3% H 2 O) at 800°C.…”

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

“…For example, pores/voids and cracks at the oxide scale can compromise thermo-mechanical integrity due to spallation of oxide scale. Ni-P coating, widely used for corrosion protection of steel, also improves the oxidation resistance of ferritic alloy in humidified air [24]. Significant porosity in the oxide scale is found for Ni-P-coated AISI 430 alloy [24] while negligible for nickel coating [22].…”

“…Ni-P coating, widely used for corrosion protection of steel, also improves the oxidation resistance of ferritic alloy in humidified air [24]. Significant porosity in the oxide scale is found for Ni-P-coated AISI 430 alloy [24] while negligible for nickel coating [22]. We have investigated the corrosion of ∼5 μm thick nickel and Ni-P-coated AISI 430 alloy, a commercial ferritic alloy with similar properties of specialized Crofer 22 APU and AISI 441, in dry (Ar-3% H 2 ) and humidified hydrogen (Ar-3% H 2 -3% H 2 O) at 800°C.…”