Anticorrosive interfacial coatings for metallic substrates

Abstract

The present state-of-the-art in anticorrosive coatings technology is a multistep process where multilayered hybrid coatings are applied on metallic substrates with each layer having certain functionality and properties. These layers are mainly an interfacial layer, such as inorganic phosphate coatings and/or sol-gel hybrid coatings, which are accompanied by a paint/polymer topcoat. While the main characteristic of the polymer topcoat is a "barrier" role to prevent the diffusion of corrosive species to the metal surface, the primer or the first layer in contact with metal surface is of significant importance due to its role in "active" corrosion prevention capability and promotion of strong adhesion between the substrate surface and subsequent layers. In this article, recent developments in processing and functional properties of zinc-phosphate sacrificial primers and sol-gel-based hybrid coatings will be overviewed. Finally, some of the innovative advancements in this area developed by this research group and others will also be discussed.

Natural Polyphenols and the Corrosion Protection of Steel: Recent Advances and Future Perspectives for Green and Promising Strategies

“…A multilayered and hybrid coating system is achieved (Figure 3 [86]) and is composed of the interfacial or primer layer and a topcoat, that acts as a barrier to external corrosion, against the diffusion of oxygen, water, and corrosive compounds, such as chloride ions, to the metal surface. Primer layers play a key functional role because they markedly contribute to the efficiency of corrosion prevention [86]. Moreover, primers should have high cohesion towards the metal surface and ensure superior adhesion to the subsequent paint layers [87].…”

Thermal and Dry Sliding Wear Behavior of Plasma Sprayed Red Mud-Fly Ash Coatings on Mild Steel

“…The operating conditions implemented are given in Table 1. Design is conducted in accordance with L 27 (3 13 ) orthogonal array and corresponding linear graph is shown in Fig. 3.…”

“…Literature reveals bond strength of Al-Si coating on mild steel by kinetic spraying deposition technique [11]. Results of adhesion measurements for different systems of steel sheet-phosphate inter layer ceramic coating are described [12,13].The development of new coating technological methods is still in progress. Relatively simple and low-cost manufacturing technique of thermal barrier coatings has been developed, which is called the slurry spray technique [14].…”

Modified Zinc Phosphate Coatings: A Promising Approach to Enhance the Anti-Corrosion Properties of Reinforcing Steel

“…When the steel comes into contact with phosphate solution which is basically a phosphoric acid-based solution, an electrochemical reaction takes place where Fe 2+ start to dissolve and release electrons at the anodic site, and the reduction of H + occurs at the cathodic site. The evolution of hydrogen and consumption of H + ions results in a local increase of pH at the surface leading to precipitation of zinc phosphate crystals [29]. According to Zimmermann [23], Donofrio [30] and Kunst [31], the possible reactions taking place in the zinc phosphating bath are as follows: …”