| WU Hui,WANG Jihu,WEN Shaoguo,DING Shengnan,SONG Jia,WANG Haopeng,SUI Peichen.Preparation of Magnesium-aluminium Hydrotalcite and Corrosion Resistance of Its Composite Coatings[J],53(12):126-134 |
| Preparation of Magnesium-aluminium Hydrotalcite and Corrosion Resistance of Its Composite Coatings |
| Received:July 29, 2023 Revised:November 02, 2023 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2024.12.010 |
| KeyWord:s, 2011, 32(11):18-23. |
| Author | Institution |
| WU Hui |
College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai , China |
| WANG Jihu |
College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai , China |
| WEN Shaoguo |
College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai , China |
| DING Shengnan |
College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai , China |
| SONG Jia |
College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai , China |
| WANG Haopeng |
College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai , China |
| SUI Peichen |
College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai , China |
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| Abstract: |
| In order to improve the corrosion resistance of waterborne industrial coatings, anti-corrosion fillers containing zinc are often added. However, with the increasing environmental requirements and the European Union's zinc restriction decree, lamellar zinc-free magnesium aluminum hydrotalcite (MgAl-LDHs) is expected to be used to replace zinc-containing fillers in coatings. Hydrotalcite (LDHs) has a layered structure, as well as features such as ion exchangeability, thermal stability, modifiable compositional structure, and recoverability. In this paper, the Zn-free hydrotalcite composite filler was synthesized by co-precipitation method, which is a commonly used method at present. The surface of the filler was modified by silane coupling agent, and finally added to the acrylic resin to prepare an anticorrosive coating. The relationship between different preparation process and the structure of hydrotalcite was explored to study the effect of MgAl-LDHs content on corrosion resistance of composite coating and determine the optimal content of MgAl-LDHs by analyzing the effect of MgAl-LDHs on the corrosion resistance of the composite coating. The crystal structure and phase composition of hydrotalcite were analyzed by X-Ray Diffraction (XRD). The surface morphology, particle size and dispersion of the filler were observed by scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) was used to determine the active functional groups present in the hydrotalcite, which was beneficial to surface modification and improved the interaction between the filler and the resin. The corrosion rate and anti-corrosion effect of fillers on the coating were evaluated by Tafel polarization curve and electrochemical impedance spectroscopy. In addition, the salt spray resistance of the coating was tested. In this work, the BGB 2300 tinplate steel (80 mm×25 mm×0.28 mm) was used as the metal substrate, and the D012 acrylic acid coating was rolled on the surface of the metal substrate. The test samples of the D012 acrylic acid coating/BGB 2300 tinplate steel system was put it into a salt spray resistant box. The test samples were divided into 3 cycles:24, 72, 96 h. The macro morphology of the acrylic acid coating surface. Through comparative experiments, it can be found that when n(Mg2+)∶n(Al3+)=2∶1 and the titration endpoint pH=11, relatively perfect Mg-Al hydrotalc with lamellar morphology, high crystallinity and complete structure could be prepared. The results of FTIR and suspension test showed that when MgAl-LDHs were successfully modified by KH570, the surface was transformed from hydrophilic to hydrophobic, which effectively increased the compatibility with the resin. The electrochemical test results show that the coating with 5wt.% hydrotalcite has the best anti-corrosion performance after soaking for 240 h. The lowest Tafel current density is 6.35 μA/cm2, and the curvature radius of the resistance arc is the largest. At the same time, the salt spray resistance test shows that the coating with 5wt.% filler also has the best corrosion resistance, which is consistent with the electrochemical test results. MgAl-LDHs, as a new type of zinc-free pigment filler, can effectively improve the anti-corrosion performance of the coating, and has a broad application prospect in the future. |
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