Properties of Carbon Nanotubes and Zinc
Carbon-based products are well known for their uniquely light weight, unparalleled strength and conductivity. These are the driving principles behind the innovation that led to the creation of carbon nanotubes- structures that are a fraction of the width of a human hair but possess the reinforcing strength of rebar.
Zinc, on the other hand, is a material best known for its high electrochemical reactivity. This makes it one of the most popular choices in preventing corrosion of steel through a process known as cathodic protection. Cathodic protection operates on a simple principle of preferential chemical reactivity. When exposed to an electrolyte like saltwater, steel will readily give up its valent electrons to react with oxygen. This exchange, called oxidation, is what produces corrosion on the surface of metals. For cathodic protection to be effective, a metal that is prone to corrosion is treated with an outer coating of a more electrochemically reactive metal like zinc. Thanks to its high electrochemical reactivity, the zinc will more readily give up its electrons than the metal beneath when in contact with the electrolyte. In this electron exchange zinc acts as a sacrificial anode which preserves the integrity of the steel asset.
CNTs and Zinc Synergize to Reduce Offshore Corrosion
Traditionally, galvanizing or plating the steel with a layer of zinc to provide cathodic protection is very expensive, drastically increases lead times, and is difficult to repair in the field. The zinc layer will not be enough to protect the metal on its own when continuously faced with the relentless conditions of marine and offshore environments. Rather than plate every component with molten zinc, many offshore structures are instead protected by a coating which contains zinc and CNTs.
While CNTs may not seem to have much to do with zinc at an initial glance, the two function very well together as an electrically conductive pair. When distributed throughout a nanocoating, CNTs act as an electrically conductive network of hundreds of thousands of nanowires, similar to a grid of power lines. These conductive nanowires allow for valence electrons held by zinc atoms to be distributed freely across the CNT network. In other words, electrons can move freely across an entire nanocoating containing zinc and CNTs.
The presence of a coating zinc and CNTs on a metal structure in a saltwater environment enable cathodic protection to take place. In cathodic protection, a reactive metal anode (zinc) corrodes in place of a steel or iron cathode by more readily giving up its electrons when exposed to both a flow of electricity and an electrolyte such as sea water. Cathodic protection is crucial to maintaining the robustness of steel structures in offshore applications, especially in oil and gas facilities. The presence of zinc and CNTs across the entire surface of a marine structure dramatically slows down the rate of corrosion by not only allowing zinc to degrade in place of the metal it is protecting, but also by allowing additional electrons to flow from lesser exposed portions of a structure to be sacrificed in cathodic protection on areas that make high contact with seawater.
Looking for Zinc Rich Coatings? Meet TESLAN® ZINC CNT PRIMERS
Tesla NanoCoatings’ flagship product line is a two-step nanocoating system. The most commonly selected initial layer of material in this system is the TESLAN® 1102 ZINC CNT PRIMER– a primer that is rich in both zinc and CNT content. This primer is specifically formulated with marine and offshore applications in mind to strengthen cathodic protection of metal structures. This is best combined with TESLAN 3102 CNT TOPCOAT which offers unparalleled resistance to mechanical damage, thermal degradation, and photodegradation caused by UV exposure.
Compared to traditional 3 coat offshore systems, TNC’s solutions are markedly more robust, apply more quickly, and offer the lowest total installed cost. Applying a nanocoating from TNC is as easy as painting a single layer- you don’t even have to wait for it to dry completely before applying a topcoat! CNT technology delivers superior coating strength, longevity, and weather resistance. Combined with the presence of electrochemically reactive zinc, our coatings offer cathodic protection for offshore steel assets that other coatings just can’t match.
To learn more about TESLAN® ZINC CNT PRIMERS and other Tesla NanoCoatings technologies, visit our About Page. If you’re interested in utilizing our coatings in your marine and offshore operations, contact us today.