Ayoola, A. A. and Durodola, B. and Fayomi, O. S. I and Obigwe, C. and Agbeyegbe, A. and Okoji, Anthony I. (2024) IMPROVING ZINC PHOSPHATING TECHNIQUE USING CALCIUM OXIDE AND MAGNESIUM OXIDE. Rasayan Journal of Chemistry, 17 (3). |1324-1332. ISSN 0974-1496 | e-ISSN: 0976-0083
![[img]](http://eprints.covenantuniversity.edu.ng/style/images/fileicons/application_pdf.png) |
PDF
Download (1MB) |
Abstract
This study aims to improve the zinc phosphating technique, an industrial conversion coating technique, by investigating the performance of both calcium oxide and a combination of calcium oxide and magnesium oxide as particle modifiers in the zinc phosphating process. Mild steel samples were subjected to chemical pretreatment (degreasing, pickling, and activation) before being subjected to a zinc phosphate bath with process variables of phosphating temperatures (65℃ and 80℃), phosphating time (40, 60, and 80 minutes) and additive concentrations (calcium oxide and a combination of calcium oxide and magnesium oxide) of 0.9 g/L and 1.8 g/L. The SEM/EDX analysis of the coated samples was carried out before the sample weight loss test. For the calcium-modified phosphating process, bath conditions of 65 ℃ and 1.8 g/L produce a more uniform coating formation, with SEM/EDX analysis. A very high average inhibition efficiency of 54.11% was obtained for the coated mild steel at 65℃ and 1.8 g/L for calcium calcium-modified zinc phosphating process. For the calcium-magnesium additive-modified phosphate process, conditions of 80℃ and 1.8 g/L concentration gave the best coating. That is, the MgO and CaO-modified zinc phosphating process had a better synergetic and compatibility behavior at temperatures of 80℃ and increased additive concentration, with an inhibition efficiency of 32.68%. Based on the values of Kads and ΔGads obtained, both the calcium additive adsorption process and calciummagnesium additive adsorption process can be described by Langmuir and Freundlich isotherms. In each case, the adsorption process was physical adsorption and the process was exothermic, as justified by ΔHads.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Calcium Oxide, Coating, Corrosion, Magnesium Oxide, Zinc Phosphating |
| Subjects: | T Technology > TP Chemical technology |
| Divisions: | Faculty of Engineering, Science and Mathematics > School of Engineering Sciences |
| Depositing User: | Patricia Nwokealisi |
| Date Deposited: | 03 Mar 2025 15:28 |
| Last Modified: | 03 Mar 2025 15:28 |
| URI: | http://eprints.covenantuniversity.edu.ng/id/eprint/18846 |
Actions (login required)
 |
View Item |
