Dear Dr. Wan Mohamad Ikhmal ,

as you said, in recent years, research to identify and incorporate new ‘green’ (environmentally friendly) corrosion inhibitors into corrosion protective coatings has been a growing area in the field of corrosion protection.

These new corrosion inhibitors present opportunities, as well as challenges, in new corrosion protective coatings development. Organic inhibitors can be reactive, thus rendering them incompatible with coating systems, while inorganic corrosion inhibitors can be both reactive and highly water soluble.

For more details, please see the source:

- Microencapsulated indicators and inhibitors for corrosion detection and control

L.M. Calle, W. Li

in Handbook of Smart Coatings for Materials Protection, 2014

An abstract, regarding “Corrosion inhibitor delyvery system” is available at:

https://www.sciencedirect.com/topics/chemistry/corrosion-inhibitor

and I suggest you also to have a look at the following documents:

-Green Inhibitors for Corrosion Protection of Metals and Alloys: An Overview

B. E. Amitha Rani and Bharathi Bai J. Basu

International Journal of Corrosion, Article ID 380217 (2012)

Available at: https://www.hindawi.com/journals/ijc/2012/380217/

- Corrosion Inhibitors – Principles, Mechanisms and Applications

Alexandre Ferreira Galio, Camila G. Dariva

in book: Developments in Corrosion Protection Edition: 1st Chapter: Corrosion Inhibitors – Principles, Mechanisms and ApplicationsPublisher: InTechEditors: M. Aliofkhazraei (2014)

Available, on RG, at: https://www.researchgate.net/publication/260264538_Corrosion_Inhibitors_-_Principles_Mechanisms_and_Applications

- Emerging Corrosion Inhibitors for Interfacial Coating

Mona Taghavikish, Naba Kumar Dutta, and Namita Roy Choudhury

Coatings, 7(12), 217 (2017)

Available at: https://www.mdpi.com/2079-6412/7/12/217/htm

-Self-healing and superhydrophobic coatings for corrosion inhibition and protection

Manoj, A., Ramachandran, R. & Menezes, P.L.

Int. J. Adv. Manuf. Technol., 106, 2119–2131 (2020)

Available at: https://link.springer.com/article/10.1007/s00170-019-04758-z

My best regards, Pierluigi Traverso

Dear Wan Mohamad Ikhmal;

The corrosion Inhibitors used to reduce the corrosion rate by decreasing the reaction of the metal with the surrounding environment. this can be achieved in several ways. Chemical compounds with antioxidant activity can be used as corrosion inhibitors. The advantage of these inhibitors is to:

Reduce the ions and mass adsorption on the metal surface.

Decrease the anodic reaction on the metal surface.

The inhibitor may be an inorganic compound like chromate, nitrate phosphate which passivates the metal or an organic compound like thiourea, amines, octynol etc. Corrosion inhibitors are chemical products which, when added to water or to any other process fluid, slow down the rate of corrosion. They are normally classified as anodic, cathodic, film-forming and oxygen-absorbing agents depending on their mode of action. more details in theses references;

• https://www.nature.com/articles/s41598-020-61810-9
• https://www.suezwaterhandbook.com/water-and-generalities/corrosion-in-metal-and-concrete/protection-against-corrosion/corrosion-inhibitors

Dear Dr. Mahmood H. M.

Yes, that seems to be the case if the inhibitors are used individually in aggressive medium. But, what if now the inhibitors are incorporated inside an anticorrosion coating/paint? Does it retain these mechanisms which you have described?

dear Wan Mohamad Ikhmal;

The corrosion inhibitor usually used either for effect on the corrosive medium or isolate the corrosion substrate. the coating is kind of the isolating to protect the material. if you have an idea for specific corrosion-resistant coating react with the environment to produce inhibiting agent? this is not clear, please could you specify?

Dear Dr. Mahmood H. M.

The following are some example of the incorporation of corrosion inhibitors in coatings and how this has improved the coatings efficiency:

1. Development of anti-corrosive paint incorporated with henna extract as a natural inhibitor

Available at: Article Development of anti-corrosive paint incorporated with henna ...

2. Improved Corrosion Protection Due to Organic Corrosion Inhibitors in Waterborne Paint Coatings

Available at: https://www.paint.org/coatingstech-magazine/articles/improved-corrosion-protection-due-organic-corrosion-inhibitors-waterborne-paint-coatings/

3. Green Corrosion Inhibitory Potentials of Cassava Plant (Manihot esculenta Crantz) Extract Nanoparticles (CPENPs) in Coatings for Oil and Gas Pipeline

Available at: Chapter Green Corrosion Inhibitory Potentials of Cassava Plant ( Man...

4. Henna leaves extract as a corrosion inhibitor in acrylic resin coating

Available at: Article Henna leaves extract as a corrosion inhibitor in acrylic resin coating

Dear Wan Mohamad Ikhmal ;

In my opinion, the corrosion is related to the reaction between the metal substrate and the surrounding environment. the inhibitor is an additive to the environment to protect the metal from corrosion. but these examples look like an additive to the protective coating to improve its corrosion protecting property. Even though it inhibits the corrosion, it seems like it related to the coating specification and coating protection efficiency than the corrosion inhibitor.

Dear Dr. Wan Mohamad Ikhmal ,

as you said, in recent years, research to identify and incorporate new ‘green’ (environmentally friendly) corrosion inhibitors into corrosion protective coatings has been a growing area in the field of corrosion protection.

These new corrosion inhibitors present opportunities, as well as challenges, in new corrosion protective coatings development. Organic inhibitors can be reactive, thus rendering them incompatible with coating systems, while inorganic corrosion inhibitors can be both reactive and highly water soluble.

For more details, please see the source:

- Microencapsulated indicators and inhibitors for corrosion detection and control

L.M. Calle, W. Li

in Handbook of Smart Coatings for Materials Protection, 2014

An abstract, regarding “Corrosion inhibitor delyvery system” is available at:

https://www.sciencedirect.com/topics/chemistry/corrosion-inhibitor

and I suggest you also to have a look at the following documents:

-Green Inhibitors for Corrosion Protection of Metals and Alloys: An Overview

B. E. Amitha Rani and Bharathi Bai J. Basu

International Journal of Corrosion, Article ID 380217 (2012)

Available at: https://www.hindawi.com/journals/ijc/2012/380217/

- Corrosion Inhibitors – Principles, Mechanisms and Applications

Alexandre Ferreira Galio, Camila G. Dariva

in book: Developments in Corrosion Protection Edition: 1st Chapter: Corrosion Inhibitors – Principles, Mechanisms and ApplicationsPublisher: InTechEditors: M. Aliofkhazraei (2014)

Available, on RG, at: https://www.researchgate.net/publication/260264538_Corrosion_Inhibitors_-_Principles_Mechanisms_and_Applications

- Emerging Corrosion Inhibitors for Interfacial Coating

Mona Taghavikish, Naba Kumar Dutta, and Namita Roy Choudhury

Coatings, 7(12), 217 (2017)

Available at: https://www.mdpi.com/2079-6412/7/12/217/htm

-Self-healing and superhydrophobic coatings for corrosion inhibition and protection

Manoj, A., Ramachandran, R. & Menezes, P.L.

Int. J. Adv. Manuf. Technol., 106, 2119–2131 (2020)

Available at: https://link.springer.com/article/10.1007/s00170-019-04758-z

My best regards, Pierluigi Traverso

See this link

https://www.sciencedirect.com/topics/chemistry/corrosion-inhibitor

we do Corrosion inhibitor injection in 45 kilometer long 20 inch dia Natural gas pipe line . The purpose of CI is to provide a layer of coating on inner walls of pipeline for some time period to prevent inner corrosion.

thump rule is when iron particles in condensate are more 100 ppm , Corrosion inhibitor must be injected either by Continuous injection or Between two soft pigs

Yes dear Wan Mohamad Ikhmal you put down a very interesting question . So I will lean on my own experience in this respect and the published works to put a short explanation relevant to this subject.

Now, there are many published works revealed that the incorporation of micro and/or nanometallic particles to polymeric matrix as coating materials will enhance the protective properties of such coatings and so mitigate the corrosion rate. These additions called as corrosion inhibitor in anticorrosion coating .

It's also discussed the effect of particles loading percent , type, size and temperature on the inhibition ability of such coating composite by the evidenced of obtaining highest corrosion resistance at higher corrosion potential and lower corrosion current values .The proposed mechanism for this inhibition is that the using of such addition in coating matrix could increase the length of the diffusion pathways for reactive corrosive species in polymeric coatings matrix and leads to a remarkable improvement in the corrosion inhibition of metallic substrate compared to normal polymer coating.

These improvements could be due to several factors. The one which is effective in our discussion is the surface area of the incorporated particles .This interfacial area between particles and matrix leads (in case of highly bonded particles)to a significant interaction zone volume fraction of polymer surrounding the particles which is affected by the particle surface and has properties different from the bulk polymer.

This volume fraction increases with particles loading percent or with decreasing the particles size toward the nano scale where the surface to volume ratio become very large. In this case the substantial increase in the interface area which is the characteristic of nanocomposites and so, much more significant volume fraction of polymer surrounding the particles affected by the particle surface and so the inhibition efficiency will depend on the volume fraction of these interaction zones.

Now the full inhibition could be reached when these interaction zones each connected with other by means of increasing the particles loading or by decreasing the size or by using particles with high aspect ratio. In this case the diffusion path through the coatings matrix will be very very long and the metallic substrate being far from the effect of corrosive environment.

Hope these explanations is helpful.

Best regards