Abstract
Calcium phosphate was encapsulated into mesoporous silica nanoparticles (MSN). The effect of pH on the structure and morphology of the MSN and the release of calcium phosphate from the MSN was investigated. Epoxy coatings with encapsulated (3 wt%) and non-encapsulated (3 wt% and 5 wt%) calcium phosphate were formulated and their anti-corrosive performance was evaluated by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) techniques. Results showed that encapsulation of the calcium phosphate as inhibitive pigment in the coating can enhance the anti-corrosive performance by preventing spontaneous pigment dissolution and controlling the pigment's release from the coating.
Highlights
Applying organic coatings is the most common way to protect metal structures from corrosion failures
Epoxy coatings with encapsulated (3 wt%) and non-encapsulated (3 wt% and 5 wt%) calcium phosphate were formulated and their anti-corrosive performance was evaluated by open circuit potential (OCP) and electro chemical impedance spectroscopy (EIS) techniques
Results showed that encapsulation of the calcium phosphate as inhibitive pigment in the coating can enhance the anti-corrosive performance by preventing spontaneous pigment dissolution and controlling the pigment's release from the coating
Summary
Applying organic coatings is the most common way to protect metal structures from corrosion failures. An anti-corrosive coating offers an effective physical barrier, impeding the diffusion of corrosive species to the metal substrate [1]. To enhance the coatings' anti-corrosive prop erties, the addition of pigments that inhibit the corrosion process is required if the barrier effect is disrupted [2]. The role of inhibitive pigments is to passivate the substrate by building up a protective layer, which hinders the further transportation of aggressive species. The pigment dissolves due to water penetration and travels to the coatingsubstrate interface where the inhibitive ions react and form a passive layer with the metal substrate [3,4]. Zinc phosphate is more commonly used as a non-toxic alternative in coating formulations. Alternatives like calcium phosphate have been adopted commer cially [7,8]
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