Interaction of alloy Fe─Al─Cr─C with the melt of alkali metals carbonates

E.V. Nikitina

KEYWORDS:

corrosion, molten carbonates of alkali metals, passivation, alumochromite.

ABSTRACT:

Interaction of Fe ─Al ─Cr─ C ( Fe- 29.5 wt.%, Cr – 29.35%, C – 2.56%, Al – 38.59%) alloy with the melt of lithium, sodium, potassium carbonates, containing from 1 to 5 wt % of additions to the salt phase in the temperature range of 500-600 °C was studied using gravimetric technique, methods of corrosion potentials measurement and anode polarization curves. Substances decreasing corrosion losses due to hardening and thickening oxide film (lithium, sodium, and potassium hydroxides) were used as passivators. As stimulators (activators) of corrosion the sodium chloride, fluoride, and sulfate were chosen. Co-alloying of iron by chrome and aluminum leads to high corrosion resistivity as to front (continuous) as to local (pitting, pit, intercrystalline) corrosion as a result of formating chemical and adhesion oxide layers. According to the XRD data the gamma aluminum oxide, spinel traces (alumochromite) and lithium aluminate were found on the surface.