High aspect ratio to deliver anti-corrosion properties

The main function of anti-corrosion coatings is to protect steel structures against corrosion and chemicals. For the corrosion protection of steel structures situated in the most severe environmental conditions, predominantly two-component epoxy type of coatings is being used as the anti-corrosive protection layer. MicaFort improves the function of these industrial protective coatings.

MicaFort as an anti-corrosion coating additive in paint

MicaFort is produced from the naturally occurring minerals Phlogopite and Muscovitemica with several properties that all together make it unique in its features for use in a metal coating:

• a very high aspect ratio,
• a narrow particle size distribution,
• retaining of platy particles even after processing to ultrafine powder,
• lower density, lower weight, and lower formulation costs compared to commonly used platy fillers.

In general, flat, platy particles overlap in a film and prevent water, oxygen or other chemicals to reach the metal basis directly, meaning the time for corrosion stimulators to start their work is increased. The addition of such platy additives in rust prevention, anti-corrosive and concrete paints ensures optimal performances for surface protection.

Testing MicaFort in corrosion resistant coatings

We have completed an extensive testing programme throughout 2015 where MicaFort in corrosion resistant coatings were tested. We aimed to show the differences in the corrosion protective performance of Phlogopite and Muscovite Mica compared to other platy mineral fillers in a barrier coating.

The tests have been run by Electrochemical Impedance Spectroscopy (EIS) method and salt spray testing. The first mentioned has recently been introduced as a fast and reliable method to assess the anti-corrosive properties of a coating system. To prove the results, LKAB Minerals Research and Development team has also conducted extensive and time-consuming salt spray testing, fortunately producing the same results. The mineral filler has only been incorporated into an intermediate coat.

EIS Testing results

Salt Spray Testing results

As can be seen in the above results overview the type of mineral filler being used has a strong influence on the anti-corrosive properties of the coating. Compared to the reference, where no lamellar filler has been used, some formulations containing these have similar anti-corrosive performance. However, Electrochemical Impedance Spectroscopy clearly shows the advantages of both Phlogopite and Muscovite Mica but especially the newly developed grade MicaFort MM75, a Micronised Muscovite grade which shows a significant performance increase of the anti-rust coating. MicaFort MM75 is a very fine Mica product with a particle size top cut of 75 microns (D₉₈).

MicaFort in a metal coating

As it was decided to omit the use of a primer and top coat for this study and no other anti-corrosive pigments or additives have been used, it was interesting to see that by applying only one coat of an epoxy paint containing MicaFort the C5-M class of anti-corrosive behavior was achieved. It is expected that by optimization, i.e. including a primer and top coat, plus incorporating active anti-corrosion additives, one can further improve the corrosion resistance.

Micronised Muscovite Mica, in this case especially MicaFort MM75, is extremely well suited for anti-corrosive properties due to its well-defined shape and morphology.

Get in contact with us if you want to know more or have additional questions about our MicaFort in anti-corrosion coatings by finding your local contact in the contact field at the bottom of this page.