Abstract

In the current investigation, we targeted to improve the adhesion and corrosion resistant behavior of AZ31 Mg alloy by executing the two-stage treatment; initially by anodization then followed by the deposition of polyurethane (PU) coatings. The impact of the different anodized layers on the adhesion and corrosion protective performance of PU-coated AZ31 Mg substrates was systematically estimated by various characterization techniques. Surface characterization results revealed the influence of silicate content in the anodization bath on the surface microstructure of anodized layers. Surface wettability of Mg substrates after anodization was significantly improved (nearly 25°), confirming the enhanced surface hydrophilicity, possibly due to the higher surface roughness. From the scratch test results, the PU/A75Si coating exhibited the highest adhesion strength with a critical load of 4.8 ± 0.3, which corresponds to about ten-fold of improvement in comparison to PU/Bare. Corrosion test results confirmed the enhanced corrosion protection behavior of PU/A75Si coatings with higher values of R_ct (8.72 × 10⁷ Ω cm²), and R_f (1.881 × 10⁷ Ω cm²) with the lowest values of i_corr (2.0120 × 10⁻¹⁰ Acm⁻²) compared to that of PU/Bare samples. Based on the attained outcomes, it was concluded that the anodized layer could increase the adhesion between the polyurethane coatings and base substrate, which is the necessary factor in enhancing the corrosion resistant behavior of polyurethane coatings on AZ31 Mg substrates.

中文翻译：

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用于航空航天的阳极氧化镁合金上聚氨酯涂料的改进的附着力和耐腐蚀性能

摘要

在目前的研究中，我们的目标是通过执行两阶段处理来改善AZ31镁合金的附着力和耐腐蚀性能。首先进行阳极氧化，然后再沉积聚氨酯（PU）涂层。通过各种表征技术，系统地评估了不同阳极氧化层对PU涂层AZ31 Mg基材的附着力和腐蚀防护性能的影响。表面表征结果揭示了阳极氧化浴中硅酸盐含量对阳极氧化层表面微观结构的影响。阳极氧化后，Mg基材的表面润湿性得到了显着改善（接近25°），这证实了增强的表面亲水性（可能是由于较高的表面粗糙度）。从划痕测试结果来看，PU / A75Si涂层表现出最高的粘合强度，临界载荷为4.8±0.3，与PU / Bare相比，提高了约十倍。腐蚀测试结果证实，PU / A75Si涂层具有更高的腐蚀防护性能，具有更高的腐蚀防护性能。[R _CT（8.72×10 ⁷  Ω厘米²），和- [R _˚F（1.881×10 ⁷  Ω厘米²）用的最低值我_更正件（2.0120×10 ^-10 了Acm ^-2相比PU /裸的样品）。根据获得的结果，可以得出结论，阳极氧化层可以增加聚氨酯涂层与基础基材之间的附着力，这是增强AZ31 Mg基材上聚氨酯涂层的耐腐蚀性能的必要因素。