The growth of iron oxide films on carbon steel and platinum surfaces in LiOH and NaOH solutions at 285°C

The Electrochemistry of Iron in lM Lithium Hydroxide Solution at 22° and 200°C

“…Evidence for the nucleating and growth of these crystals from solution has been assembled by Castle et aL (15,34). Additional evidence has been obtained in this laboratory (33) including the observation of growth steps (Fig. 10) on the faces of crystals grown on iron and carbon steel in 1M LiOH at 200~ The potential dependence of the origin of the octahedral crystals was illustrated experimentally by potentiostating an iron electrode at --1400 mV for 24 hr at 200~ Examination of the surface did not reveal any "upper layer" oxide crystal.s even though the conditions chosen were such that nucleation would have occurred in a few minutes on open circuit.…”

“…Further, previous studies (4,17,32) have shown that the oxide formed on iron and carbon steel under similar conditions is magnetite, Fe804, with the possible inclusion of a small amount of LiFeO2 (4). We have found that both FesO4 and LiFeO2 crystals nucleate and grow on platinum in 1M LiOH at 285~ in the presence of a corroding carbon steel surface (33). These crystals were found to have a similar morphology to the crystals which form the "upper layer" on the corroded steel surface.…”