Corrosion inhibition of Al 6061 T6/Al₂O₃p 10% (v/v) composite in 3.5% NaCl solution with addition of cerium (III) chloride

Abstract

The effect of cerium on corrosion inhibition of Al 6061 T6/Al 2 O 3 p 10% (v/v) metal matrix composite in aerated 3.5% NaCl solution after different immersion times at room temperature and pressure was investigated.Experimental tests were conducted at different inhibitor agent concentrations (0, 200, 1000 and 2000 ppm of cerium) and for exposure times ranging from 2 h to 30 days. Corrosion inhibition power evaluation and surface layer characterization have been carried out by electrochemical (polarization potentiodynamic curves and impedance measurements) and free corrosion tests followed by several instrumental analyses (optical microscopy, x-ray photoelectron spectroscopy, scanning electron microscopy).Electrochemical data have shown that cerium compounds offer a noticeable inhibition level against localized corrosion in all considered cases and that the maximum protective power against corrosion attack is evident when the inhibitor is added at a 200 ppm concentration. Surface analysis revealed chemical and morphological characteristics of the passive layer. In particular, a higher amount of inhibitor led to the formation of a surface film with a higher content of cerium but without homogeneous distribution. This behaviour decreased the protection power of the passive layer while increasing composite substrate corrosion tendency.

Inhibition of the Oxygen Reduction Reaction on Copper with Cobalt, Cerium, and Molybdate Ions

“…Cerium has been proposed as an inhibitor for a variety of materials, such as steel, 55 tinplate, 56 zinc, 43,44 Cu, [46][47][48] Al, 57 and several aluminum alloys. [49][50][51][58][59][60][61] At potentials where ORR takes place on Cu, it has been suggested that the initial film contains Ce͑III͒, but as the Cu is exposed for longer * Electrochemical Society Student Member. ** Electrochemical Society Active Member.…”

“…22,42 It has also been shown 53 that a Ce coating could have performance comparable to that of the chromate conversion coatings, but required a long time ͑4-5 days͒ to form. Cerium has been investigated as a possible inhibitor used as conversion coating, [49][50][51] applied by anodization, 52 cathodic polarization, 46,47 or long exposure at open-circuit potential ͑OCP͒. 53 In some cases, the formation of the film is accelerated by an oxidizer.…”

Self-healing coatings

“…Pourbaix diagrams are often used as a guide for the types of deposit that might provide cathodic inhibition [128]. The deposit is usually a hydroxy-oxide, with rare earths currently of great interest [129][130][131][132][133][134][135][136][137][138]. Transition metal phosphates have traditionally been of great importance as well [139][140][141][142][143][144].…”

Improving the protective properties of La‐conversion coating on α‐brass surface by the combined use of La2O3 nanoparticles incorporation and electrodeposition

“…In spite of the fact that brass is a relatively noble metal, it can susceptibly suffer dissolution of zinc 1, 2, stress corrosion cracking 3, 4 and pitting corrosion 5, 6, when exposed to aggressive anions, such as Cl − ions 7. Different techniques have been proposed and applied to protect brass from corrosion and, among them, chemical conversion treatments based on rare earth elements, which have been used as a green alternative for the chromium species via direct immersion in rare earth salt solutions 8, 9 and rare earth conversion coatings 10, 11.…”