Zinc ferrocyanide as novel inhibiting and sensing pigment in protective coatings
The fabrication and application of zinc ferrocyanide ion exchange compounds for use as inhibiting and sensing pigments in protective paints and primers for metals and alloys are described in a paper.
A distinctive property of these ferrocyanide pigments is an ability to store corrosion inhibitors and then release them when needed by an ion exchange process.
Good protection on aluminum alloy
The exchange process is triggered when moisture containing Na+ and K+ ions contacts inhibitor particles embedded in an organic coating. The exchange kinetics were studied by measuring the concentration of released zinc ions in the solution with inductively coupled plasma. The inhibitor storage capacity can be as high as 200 meq/100 g, and it is much higher than that found in other reported ion exchange compounds. Furthermore, structure changes from non-crystalline to crystalline, upon exchange with alkaline ions, can be detected by x-ray diffraction, providing an important indication of activation of the corrosion protection. This is a form of corrosion sensing. The inhibition performance of zinc ferrocyanide in the coating was examined by salt spray tests and electrochemical impedance spectroscopy, and both tests showed that zinc ferrocyanide could provide good protection on aluminum alloy 2024.
The study is published in: Progress in Organic Coatings, Volume 104, March 2017, Pages 210–216
Event tip:
If you want to refresh your basic knowledge or dive in into the latest findings on protective coatings, you should visit the European Coatings Show Conference in Nuremberg, Germany. On April 2 it will host a pre-conference tutorial on the basics of protective coatings.
On April 4 there will be two complete session on protective coatings with the latest findings from some of the biggest players in the coatings industry.
