Graphene oxide:

the new ally of primary coatings in corrosion protection

Corrosion is an electrochemical reaction that occurs when the metal reacts with the surrounding environment forming ferric oxide, causing the metal to lose its main characteristics of hardness and resistance. Oxygen, temperature, humidity, contaminants, gases, and the physicochemical characteristics of water are the main factors that affect the rate at which metals corrode.

One of the most widely used methods to control corrosion is the application of protective (primer) coatings to metal surfaces. The coating forms a barrier between the substrate (metal) and the surrounding medium, retarding the deterioration or oxidation of the metal. The coatings are polymer-based substances (paints), resistant to degradation, which are used to cover the material to be protected.

Nowadays, a wide variety of primers have been developed based on different types of resin, such as the alkyd and epoxy type. Efficiency is generally associated with an increase in cost. Unfortunately, most of these coatings or paints are not perfect barriers and eventually fail due to holes or micropores in the coating or the diffusion of oxygen and water through it (they are not completely waterproof). On the other hand, the coatings continue to have low thermal resistance and above all a limited chemical resistance.

Currently Energeia – Graphenemex®, a leading Mexican company in Latin America in the research and production of graphene materials for the development of industrial applications, through its Graphenergy line, has launched a range of primers and other nanotechnological coatings.

Graphenergy anticorrosive primers are coatings based on graphene oxide (GO), a new nanotechnological additive that provides multiple properties to coatings, including extraordinary corrosion protection and barrier technology (barrier effect). Graphene oxide creates pathways that are very tortuous, which prevents oxygen and water molecules from diffusing through the coating and eventually reaching the metal surface, providing protection against corrosion (Fig. 1). These primaries can act as mentioned, by (1) forming a barrier, which greatly prevents the penetration of oxygen and water molecules, or (2) the inhibition of the corrosion process, by increasing the electrical and ionic resistivity, cutting the corrosion cycle.

Fig. 1 Mechanism of anticorrosive protection of coatings based on polymers and graphene.

Among the anticorrosive primers that are currently for sale by Graphenergy, there are two: “Graphenergy anticorrosive alkyd primer” and “Graphenergy anticorrosive epoxy primer”, each one designed according to different needs and conditions.

A. Graphenergy anticorrosive alkyd primer.

Provides high anticorrosive protection, resistance to UV rays and provides extraordinary adherence to the substrate. Ideal for the protection of industrial infrastructure, for the application of ferrous surfaces, both for interiors and exteriors. It is recommended for non-coastal areas or where humidity conditions are not high.

B. Graphenergy anticorrosive epoxy primer.

In addition, this coating offers extraordinary chemical resistance, with high wear resistance, resistance to UV rays, impermeability and greater adhesion, in order to improve the useful life of any metal surface or installation and reduce maintenance costs.

Graphene coatings provide enhanced properties and many more benefits, including:

Higher performance than existing coating technologies on the market today.
Fewer applied coating layers are required and with higher anti-corrosion protection.
Zinc reduction in formulations can reduce the amount by up to 50%.
Primers with greater chemical resistance and high thermal resistance.
Coatings with greater impermeability and non-stick effect (dirt does not adhere to it). Graphene oxide creates a two-dimensional network on the surface of the coating, which does not allow the anchoring or diffusion of water molecules or chemical substances, which allows the development of coatings with a hydrophobic effect, resulting in coatings that are easier to clean (See Fig.2).

Fig. 2. Behavior of coatings without and with graphene oxide, after subjecting them to a chemical attack (corrosive solution) for more than two hours.

Improves adhesion to the substrate. The primers with graphene oxide increase their adherence by up to 50% with respect to the control (Fig. 3).

Fig. 3. Primer adhesion test with and without graphene oxide.

More flexible coatings. The incorporation of graphene oxide not only improves adhesion, but also allows flexibility to the coating, allowing it to have high resistance to bending or greater resistance to fracture (Fig. 4).

Fig.4. Flexibility test in primary without and with graphene oxide.

Referencias

Chang, C.-H. et al. Novel Anticorrosion Coatings Prepared from Polyaniline/Graphene Composites. Carbon N. Y. 50, 5044–5051 (2012).
Fengjuan Xiao, Chen Qian, et al., et al., Progress in Organic Coatings, 125, 79-88 (2018); doi.org/10.1016/j.porgcoat.2018.08.027
Karolina Ollik and Marek Lieder. Review of the application of graphene-based coatings as anticorrosion layers. Coatings 2020, 10(9), 883. 2020.
Zhang J., Kong, G., Li S., Le Y., Che C., Zhang S., Lai D., Liao X. Graphene-reinforced epoxy powder coating to achieve high performance wear and corrosion resistance. 20:1448-4160, 2020.
Ghosh Tuhin and Karak Niranjan. Mechanically robust hydrophobic interpenetrating polymer network-based nanocomposites of hyperbranched polyurethane and polystyrene as an effective anticorrosive coating. New J. Chem., 2020, 44, 5980-5994.

the era of graphene oxide

Corrosion is defined as the gradual deterioration of metallic materials and their properties, and occurs when the metal reacts with the surrounding environment to form rust or another chemical compound. In general, atmospheric air, humidity, rain, and aqueous solutions (chemical products) are the environments that are most frequently associated with corrosion problems.

Nowadays, corrosion damage is one of the most important problems to face for many industries in the world. It is estimated that corrosion causes economic losses of 3.4% of world GDP (about 2.5 billion dollars per year). However, there are three industries whose corrosion impact is more frequent and riskier for their processes: the chemical industry, the shipbuilding industry and the construction industry.

In the chemical industry, the use of chemical products is paramount within its operations, so equipment and machinery are in direct and constant contact with chemical substances, increasing maintenance and/or repair costs, affecting the industry budget and their production. In the case of the naval industry, humidity and salt are the main factors that contribute to the corrosion process and, consequently, the deterioration and affectation of its facilities, ships, containers and even merchandise. On the other hand, in the construction industry, both the machinery and the construction areas themselves can be affected by corrosion due to their exposure to the environment. Corrosion causes the metallic assets to weaken, generating mechanical failures, putting the work at risk.

Anticorrosive coatings are regularly used for protection against corrosion, humidity and fouling of installations, machinery and equipment. At a commercial level, there is a wide variety of anticorrosive coatings based on different additives and resins, their efficiency is generally associated with an increase in cost. However, the coatings still have low thermal and corrosion resistance and especially limited chemical resistance.

Graphene is currently the most revolutionary nanotechnological additive in the coatings and paints industry. The incorporation of graphene as an additive in coatings produces coatings with extraordinary protection against corrosion. Graphene creates pathways that are very tortuous, preventing water and oxygen molecules and/or chemical agents from diffusing to the surface of metal-based materials, resulting in metal protection against oxidation and corrosion. corrosion (Fig. 1).

Figure 1. Schematic representation of the tortuous path for oxygen and water molecules in polymer coatings with clay and graphene.

Graphene coatings provide many performance and anti-corrosion benefits, including:

Higher performance than existing coating technologies on the market today.

Fewer applied coating layers are required for greater benefits

Zinc reduction in formulations

Chemical resistance

Graphene and graphene oxide-enhanced anticorrosive coatings will replace traditional zinc-based coatings, which have several drawbacks, such as short life, high content of volatile organic compounds (VOCs), slow curing, high cost, sedimentation in storage.

Currently Energeia – Graphenemex®, a leading Mexican company in Latin America in research and production of graphene materials for the development of industrial applications, through its Graphenergy line, has launched a wide range of nanotechnological coatings with graphene. These coatings offer high anticorrosive protection, extraordinary chemical resistance, high wear resistance, resistance to UV rays, impermeability and greater adherence, in order to improve the useful life of any surface or installation and reduce maintenance costs.

References

Chang, C.-H. et al. Novel Anticorrosion Coatings Prepared from Polyaniline/Graphene Composites. Carbon N. Y. 50, 5044–5051 (2012).

Fengjuan Xiao, Chen Qian, et al., et al., Progress in Organic Coatings, 125, 79-88 (2018); doi.org/10.1016/j.porgcoat.2018.08.027

Chaudhry, A. U., Mittal, V. & Mishra, B. Inhibition and Promotion of Electrochemical Reactions by Graphene in Organic Coatings. RSC Adv. 5, 80365–80368 (2015).

Zhen, Z. & Zhu, H. Graphene: Fabrication, Characterizations, Properties and Applications. Graphene (Academic Press, 2018).