Corrosion inhibition mechanism of steel reinforcements in mortar using soluble phosphates: A critical review
The corrosion inhibition mechanism of soluble phosphates on steel reinforcement embedded in mortar fabricated with ordinary Portland cement (OPC) are reviewed. This review focuses soluble phosphate compounds, sodium monofluorophosphate (NaPOF) (MFP), disodium hydrogen phosphate (NaHPO) (DHP) and tri...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/262646 |
| Acceso en línea: | http://hdl.handle.net/10261/262646 |
| Access Level: | acceso abierto |
| Palabra clave: | Steel reinforcements Concrete Migrating corrosion inhibitors Phosphate penetration Thermodynamics Reactivity |
| Sumario: | The corrosion inhibition mechanism of soluble phosphates on steel reinforcement embedded in mortar fabricated with ordinary Portland cement (OPC) are reviewed. This review focuses soluble phosphate compounds, sodium monofluorophosphate (NaPOF) (MFP), disodium hydrogen phosphate (NaHPO) (DHP) and trisodium phosphate (NaPO) (TSP), embedded in mortar. Phosphate corrosion inhibitors have been deployed in two different ways, as migrating corrosion inhibitors (MCI), or as admixed corrosion inhibitors (ACI). The chemical stability of phosphate corrosion inhibitors depends on the pH of the solution, HPO ions being stable in the pH range of 3-6, the HPO in the pH range of 8-12, while the PO ions are stable above pH 12. The formation of iron phosphate compounds is a thermodynamically favored spontaneous reaction. Phosphate ions promote ferrous phosphate precipitation due to the higher solubility of ferric phosphate, thus producing a protective barrier layer that hinders corrosion. Therefore, the MFP as well as the DHP and TSP compounds are considered anodic corrosion inhibitors. Both types of application (MCI and ACI) of phosphate corrosion inhibitors found MFP to present the higher inhibition efficiency in the following order MFP > DHP > TSP. |
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