ปฏิกิริยาเคมีที่น่าสนใจ ฉบับ การเตรียมผิวชิ้นงาน Metals Surface Coating Reactions.

Metals Surface Coating Reactions.

        MSC are a crucial component in many industries, as they provide a protective layer to metals and improve their overall performance. prevent corrosion, reduce wear and tear, enhance appearance. With numerous types of coatings available in the market, it can be challenging to determine the best one for your application. In this article, we will discuss the 3 most common types of  coatings.
👉 Iron Coating


👉Zinc Coating


👉Zirconium Coating

        
    The pretreatment process for metal surfaces provides multiple benefits as it is the foundation of the paint layering system. A quality metal treatment process enhances adhesion between the metal and paint layers by providing a more uniform surface and provides greater corrosion resistance with less undercutting of the paint film.

Enhanced Metal Surface Pretreatment of:

💚Adhesion

💚Corrosion Protection Performance

Reaction of Iron Phosphate Coating

        Hydrogen evolution increases the pH at the metal/solution interface, which then alters the dissociation equilibrium, leading to the formation of PO4 3−

     

Deposition of an amorphous phase:

Surface Coating with Iron Phosphate



Reaction of Zinc Phosphate Coating

Hydrogen evolution increases the pH at the metal/solution interface, which then alters the dissociation equilibrium, leading to the formation of PO4 3−
Deposition of an amorphous phase:

Crystallization and crystal growth

SEM Microphotographs of Zinc Phosphate Coating


Journals ref.  Jiang, Congcong; Gao, Zidong; Pan, Hong; Cheng, Xin (2020). The initiation and formation of a double-layer phosphate conversion coating on steel. Electrochemistry Communications, (), 106676–. doi:10.1016/j.elecom.2020.106676 

        Journals ref. Bi, M.; Zhu, J.; Luo, Y.; Cai, H.; Li, X.; Wang, X.; Wei, Y.; Wang, X.; Hu, C.; Hu, J.; et al. Effect of Deposition Temperature on the Surface, Structural, and Mechanical Properties of HfO2 Using Chemical Vapor Deposition (CVD). Coatings 2022, 12, 1731. https://doi.org/10.3390/coatings12111731

Reaction of Zirconium Coating

Hypothesis of the zirconium conversion 

    The main components of the Jiuhe zirconium solution are hexafluorozirconic acid, water-soluble polymers and other traces of non-hazardous auxiliaries. The following balanced reaction can be occurred:
    Under the conditions of solution pH 4.5 and in the presence of F-, the golden yellow color of the zirconium conversion on CRS would be associated with the iron compound b-FeOOH (golden yellow color), which can only be generated in the presence of F- or Cl- .

    Furthermore, along with H? consumption, ZrO2 would be generated continually. Once more, ZrO2, b-FeOOH and water-soluble polymers fitted together and formed the zirconium conversion coating, as shown in below. Actually, as EDS results show, F content would be high so that in the reaction process [FeF6] 3- does not turn into [Fe(H2O)6] 3- completely and becomes a part of the conversion coating directly. Iron oxide hydroxide (FeOOH) has outstanding features such as environmental compatibility, high photostability and anti-aging stability as reported. the zirconium compound conversion results in excellent anticorrosion ability and binding force with powder coating.


        Journals ref.  Wu, Ai-Hua; Wang, Yao-Zu; Xu, Tong-Kuan; Li, Zhi; Luan, Sheng-Ji; Qu, Feng-Zuo (2018). Corrosion resistance properties of colored zirconium conversion coating and powder coating on cold-rolled steel. Rare Metals, (), –. doi:10.1007/s12598-017-0969-7 
        Journals ref. Wu, Ai-Hua; Wang, Yao-Zu; Xu, Tong-Kuan; Li, Zhi; Luan, Sheng-Ji; Qu, Feng-Zuo (2018). Corrosion resistance properties of colored zirconium conversion coating and powder coating on cold-rolled steel. Rare Metals, (), –. doi:10.1007/s12598-017-0969-7 


Reaction of Zirconium & Titanium Coating

       Journals ref. Sun M, Zhao T, Ma Z, Li Z. Facile preparation of macro-mesoporous zirconium titanate monoliths via a sol–gel reaction accompanied by phase separation. Journal of Materials Research. 2019;34(24):4066-4075. doi:10.1557/jmr.2019.280

        Mechanism of deposition of Zr/Ti layer on AA6016: schematic presentation of course of formation of conversion coating (left panel), and Volta potential map as a function of time of immersion in conversion bath (right panel). Reprinted from the publication by F. Andreatta, A. Turco, I. de Graeve, H. Terryn, J.H.W. de Wit, and L. Fedrizzi, Surf. Coat. Technol., 201, 7668−7685 (2007)


    Journals ref. Milošev, I.; Frankel, G. S. (2018). Review—Conversion Coatings Based on Zirconium and/or Titanium. Journal of The Electrochemical Society, 165(3), C127–C144. doi:10.1149/2.0371803jes 

Reaction of Zirconium & Organometallics Coating


        Journals ref. L.I. Fockaert, S. Pletincx, B. Boelen, T. Hauffman, H. Terryn, J.M.C. Mol,
Effect of zirconium-based conversion treatments of zinc, aluminium and magnesium on the chemisorption of ester-functionalized molecules, Applied Surface Science, Volume 508, 2020, 145199, ISSN 0169-4332, https://doi.org/10.1016/j.apsusc.2019.145199.

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