Getting smart about corrosion

Jerry Lee speaks with Olga Koper, business lead for Energy at Battelle, to find out more about the company’s corrosion resistant coating, which seeks to “heal” cracks in pipelines.

Koper.

Battling corrosion is a constant struggle in the offshore environment, and effective inspection is made more difficult when the problems are too small to see. Addressing these issues, Battelle has developed a corrosion resistant coating using novel self-healing oligomer filled microcapsules, the Smart Corrosion Detector bead. The function of this technology is to “heal” cracks caused by corrosion and indicate the location of the issue.

OE: What is the technology behind the Smart Corrosion Detector bead?

You have a capsule that is filled with an active material, which is then released upon a stimuli. It is an approach in which you are able to deliver an active material and control its release.

We use a particle forming polymerization approach to form a shell or capsule, 30-50 microns in size, which encapsulate the active material, a thermoplastic oligomer.

OE: What were some considerations during the development process?

“Smart beads,” filled with chemicals that can fill cracks caused by pipeline corrosion, are added to a coating that is painted on the asset before it is deployed. Terahertz spectroscopy devices enable maintenance personnel to identify where the beads have burst and the pipe requires repairs. Images from Battelle.

There are several different factors that you have to take into consideration with this technology. You have to ensure that the active material is stable in the capsule, does not interact with your shell material and deactivate; the capsules must be correctly sized and dispersed in your coating or paint; that it has a life shelf ability; the capsules must have the right mechanical type of strength for the application so they are not damaged when mixing within the paint or coating; and there needs to be the right amount of capillary action to ensure the active material flows out when the capsule is broken and fills the crack.

These are interesting problems because there are so many variables that you have to get just right to get the desired properties.

OE: How does Smart Corrosion Detector bead work?

If you have a surface (aluminum) that starts corroding, trivalent ions (tri-aluminum) begin to form. These ions interact with the outside of the capsule and form a complex that causes the capsule to stretch to the point of breakage. The healing agent, a thermoplastic oligomer, flows out of the capsule and fills the crack that formed during corrosion. In addition, the complex fluoresces when exposed to UV light. So, not only is the crack healed, but you’re able to see where the crack occur because it will be able to fluoresce.

OE: How is this a “smart” technology?

It is smart because the trigger is the corrosion by-product reacting with the shell of the capsule, stressing it to the point of breaking. The Smart Corrosion Detector bead mitigates corrosion and provides a visual indication, offering a multifunctional type of material that act when and where you want the action to occur.

OE: What applications are there for this technology?

The smart coating fluoresces in cracks under UV light.

This technology is focused on metals surfaces that are prone to corrosion. Since we are incorporating it into paints and coating, anywhere you can use coatings or paints you can add the capsules to have the self-healing application working. For offshore applications, we envision that it may have applications on pipelines, hardware, and equipment.

This is a flexible technology that can be used on many different equipment and surfaces. However, if the coating or paint is not able to withstand the environment, the capsules also will not be able to withstand it.

OE: What are the benefits of using the Smart Corrosion Detector bead?

Potentially, the beads can be incorporated into a paint or coating up to 10% by weight without any significant increase in the cost. Applying this paint or coating can elongate the life of your equipment so that you don’t have to change the equipment that often or reapply the paint coating. We estimate that a 10% by weight inclusion of the beads would double the life of the paint or coating. Also, when the cracks are filled, some of the original strength may return, because you no longer have the cracks that are more pliable to breakage.