2A12铝合金基体超疏水表面制备及性能研究

Preparation and performance analysis of superhydrophobic surface on 2A12 aluminum alloy

铝合金在使用过程中极易引发基体腐蚀现象,如点蚀、晶间腐蚀等,为保障铝合金在腐蚀环境中的应用,可通过建立超疏水表面改变铝合金表面的润湿性,从而在一定程度上减少腐蚀液与铝合金表面的接触,进而改善耐蚀性。本文通过酸刻蚀和沸水刻蚀两种方法在铝合金表面构筑微纳米结构,并使用低表面能物质硬脂酸进行表面处理得到超疏水表面。采用扫描电子显微镜、接触角测试仪、原子力显微镜分别对铝合金表面形貌、疏水性和粗糙度进行测试,得到两种方法的最佳制备时间,而后通过极化曲线对两种方法制备的铝合金表面耐蚀性能进行对比,进而研究两种刻蚀方法对铝合金耐蚀性的影响。实验结果表明:酸刻蚀时间为15 s时,铝合金表面接触角达到峰值163.9°,呈现超疏水状态,相对于空白样品,表面粗糙度增加了24倍,电化学自腐蚀电位正向移动0.362 8 V;沸水刻蚀时间为1 min时,其表面接触角达到峰值109.6°,比空白样品疏水性强但未呈现超疏水状态,相对于空白样品,经沸水刻蚀的铝合金表面粗糙度增加了4.4倍,电化学自腐蚀电位正向移动0.074 8 V。两种方法处理得到的铝合金表面的耐蚀性与空白铝合金试样相比均有显著提高,而酸刻蚀法的缓蚀效率远高于沸水法,可达94.13%。

Matrix corrosion phenomena such as pitting corrosion and intergranular corrosion are likely to develop during the use of aluminum alloys.For the application of aluminum alloys in corrosive environments,superhydrophobic surface can be established to change the wettability of metal surface,so as to reduce the contact between the corrosion solution and surface and improve the corrosion resistance.Micro/nano-structures were constructed on the surface of aluminum alloy by acid etching and boiling water etching,and the superhydrophobic surface was obtained by surface treatment with stearic acid,a low surface energy material.The surface morphology,hydrophobicity,and roughness of aluminum alloy were measured by scanning electron microscope,contact angle tester,and atomic force microscope,and the optimal preparation time of the two methods was obtained.Finally,polarization curves were used to compare the corrosion resistance of aluminum alloy surface prepared by the two methods,and the influence of the two etching methods on the corrosion resistance of aluminum alloy was studied.Results show that when the acid etching time was 15 s,the surface contact angle of aluminum alloy reached a maximum of 163.9°,indicating a superhydrophobic state.The surface roughness increased by 24 times in comparison to the blank sample,and the electrochemical self­corrosion potential moved 0.3628 V positively.When the boiling water etching time was 1 min,the surface contact angle peaked at 109.6°,which was more hydrophobic than the blank sample but did not exhibit superhydrophobic state.Compared with the blank sample,the surface roughness of aluminum alloy etched by boiling water increased by 4.4 times,and the electrochemical self-corrosion potential moved 0.0748 V positively.The corrosion resistance of the aluminum alloy obtained by the two methods was significandy improved compared with the blank aluminum.