Electrochemical Corrosion of Sintered Composites on the basis of Fe/FePO₄ Coated Powders

摘要

Electrochemical corrosion behaviour of sintered composites based on iron powder consisting ofspherically and/or irregularly shaped iron particles precipitation coated with FePO4 layer was studiedusing the potentiodynamic polarization test. The Fe/FePO4 coated powders containing 2 and 5 wt-% of-3 FePO4 were compacted to the density of 6650-6700 kg m and subsequently sintered at temperaturesranging from 912 to 1130C for 3 min in air. The creation of a liquid phase during heating to1130Cwith subsequent quenching into water and/or into liquid nitrogen resulted in the formation of a thin andcontinuous iron phosphate layer consisting of ~ 85 wt-% of fine lamellar phase identified as graftoniteand ~ 15 wt-% of iron oxides - wstite, magnetite and hematite. Thus prepared composites show animprovement in anti-corrosion behavior, which is associated with the formation of a protectivecontinuous layer. Silica nano-powder particles tend to agglomerate, which results in discontinuities inthe protective iron phosphate layer, with a detrimental effect on corrosion behavior of thesecomposites.