Jp. Tu et al., REACTION-MECHANISM OF PREOXIDIZED NICKEL-CHROMIUM-CERIUM ALLOY WITH CHLORINE GAS IN THE TEMPERATURE-RANGE 400-DEGREES-C TO 700-DEGREES-C, Corrosion, 53(4), 1997, pp. 312-318
High-temperature corrosion of preoxidized Ni-Cr-Ce alloys in chlorine
gas (Cl-2) at temperatures between 400 degrees C and 700 degrees C was
investigated using thermogravimetric analysis and examining the corro
sion products by scanning electron microscopy (SEM), energy-dispersive
spectroscopy (EDS), and X-ray diffraction (XRD). Corrosion resistance
of preoxidized alloys against chlorination was improved by formation
of protective nickel oxide-chromium oxide-cerium oxide (NiO-Cr2O3-CeO2
) scale. At lower temperature, the protective oxide Scale played a rol
e in the chlorination processes. With increasing reaction temperatures
, the oxide scale was destroyed after exposure to Cl-2 for a period of
time. The corrosion rate increased rapidly, and weight descreased lin
early with time. IR Cl-2 atmospheres at high temperature, Cl-2 attacke
d the oxide scale by three mechanisms: mechanical damage by volatile c
hlorides, scale pitting and spalling by Cl-2 dissolving in the scale,
and oxides being converted to chlorides.