摘要
超疏水表面具有自清洁、耐腐蚀等优异性能,在户外装饰、海洋腐蚀等领域具有广阔应用前景。然而,超疏水表面颜色单一,难以满足人们对其装饰性能的需求。作为铝合金常用的防护手段之一,超疏水表面的多彩化可以扩展铝合金在更多有装饰性需求的领域的进一步应用。通过阳极氧化工艺和低表面能物质改性,在铝合金表面分别制备了接触角为160.0°和162.7°的黑色和芥末黄色超疏水膜层。利用扫描电子显微镜(SEM)和能谱仪(EDS)分析彩色膜层改性前后表面形貌和元素组成;利用光学接触角测试仪来表征超疏水膜层的静态接触角,并对其进行了自清洁测试和大气暴露试验;利用电化学工作站研究彩色超疏水膜层在3.5%NaCl下的腐蚀性表现。结果表明:超疏水膜层的腐蚀电流密度(Icorr)较改性前下降两个数量级,较铝基体下降5个数量级,具备优异的耐蚀性能;同时彩色超疏水膜层还具备良好的自清洁性和环境适应性。
In the 1970s,the"Lotus Effect"was put forward,so that the superhydrophobic materials attracted the attention of researchers in various countries.Superhydrophobic surface referred to the surface where the water contact angle(CA)was greater than150°and the rolling angle(SA)was less than 10°.The self-cleaning,anti-fouling,anti-icing and other characteristics of superhydrophobic materials made them widely used in various fields,such as the surface protection of aluminum alloy.It could not only provide corrosion protection for aluminum alloy,but also gave aluminum substrate self-cleaning,antifouling,antibacterial and other special functions.Superhydrophobic surface colorization could make aluminum alloy better used in architectural decoration materials,shipbuilding and other fields with decorative requirements.To prepare artificial superhydrophobic surface,it was necessary to improve surface roughness and reduce surface free energy.The construction of color super hydrophobic film layer needed to add another coloring step.Specific steps included anodic oxidation,electrolytic coloring,hot water sealing and low surface energy modification.Anodic oxidation was used to preparing a layer of porous oxide film on the surface of 7A04 aluminum alloy,and then put the anodized samples into different coloring solutions for electrolytic coloring.The metal ions in the coloring solution were reduced to single substance or compound and deposited at the bottom of the porous layer,showing black(Sample H)and mustard yellow(Sample J)respectively.Hot water sealing could not only improve the color protection of color film layer,but also construct the rough structure needed for super hydrophobic surface.Finally,black(Sample S-H)and mustard yellow(Sample S-J)superhydrophobic film was successfully prepared after low surface energy modification.Scanning electron microscope(SEM)and energy spectrometer(EDS)were used to analyze the surface morphology and elements of the color film before and after modification.The static contact angle of the superhydrophobic film was characterized by the optical contact angle tester,and the self-cleaning test and atmospheric exposure test were carried out.The corrosion resistance of color superhydrophobic film was studied by electrochemical workstation.The results showed that:(1)the surface of the color film layer was covered by petal-like substances,which were the hydrated alumina generated during the hot water sealing process.A large number of hydrated alumina provided the required rough structure for the super-hydrophobic surface,and the surface structure did not change after the modification of the low-surface energy substances.(2)According to EDS detection,metal elements from the coloring solution were detected on the film surface before the modification of low surface energy,while F and Si elements from the modification solution were detected on the film surface after modification,which proved that the long chain fluoride in the modification solution was grafted to the sample surface.(3)When the droplets were in contact with the superhydrophobic surface,most of the surface area of the droplet was supported by a cushion of air provided by the coarse structure,and the droplet remains spherical on the superhydrophobic surface.The contact angles of the black and mustard yellow superhydrophobic film measured by the contact angle tester were 160°and 162.7°,respectively,showing the superhydrophobic performance.(4)During the atmospheric exposure experiment lasting up to 180 days,the static water contact angle on the color superhydrophobic surface showed an overall downward trend,but it was still greater than 150°after 180 d,indicating that the prepared color superhydrophobic film had good stability under atmospheric environment.(5)According to the self-cleaning test process recorded by high-speed digital camera,the aluminum powder on the surface carried by the droplet slided down together.The amount of aluminum powder carried by the droplet was related to the volume of the droplet.(6)According to the polarization curve,the corrosion resistance of the color superhydrophobic membrane layer at different stages showed an upward trend.The corrosion potential(Ecorr)of the aluminum alloy substrate was-0.75 V,the corrosion current density(Icorr)was 1.10×10^(-3)A·cm^(-2),Ecorrof Samples H and S-H was-0.63 and-0.31 V,and Icorrwas 3.12×10^(-6)and 1.35×10^(-8)A·cm^(-2),respectively.Ecorrof Samples J and S-J were-0.62 and-0.18 V,and Icorrof Samples J and S-J were 4.61×10^(-7)and 8.27×10^(-9)A·cm^(-2),respectively.The superhydrophobic film showed excellent corrosion resistance.The fitting results of samples’electrochemical impedance spectrum also illustrated this change.Before the modified low surface energy,the impedance modulus values of the two color films reached 1×10^(5)Ωorders of magnitude,and the modified color superhydrophobic films impedance modulus values reached more than 1×10~7Ωorders of magnitude.To sum up,the black and mustard yellow superhydrophobic films with bright luster and uniform color were prepared on the surface of 7A04 aluminum alloy by combining anodic oxidation process and low surface energy modification.The contact angle was up to 160°(Sample S-H)and 162.7°(Sample S-J),respectively,and the film had good superhydrophobicity,self-cleaning property and atmospheric environment adaptability.The results of polarization curve and electrochemical impedance spectroscopy showed that the superhydrophobic modification,as one of the common surface treatment methods for aluminum alloy protection,could provide better corrosion protection performance for aluminum alloy.
作者
徐乾坤
张玉林
解承东
李明泽
赵莹
陈飞
Xu Qiankun;Zhang Yulin;Xie Chengdong;Li Mingze;Zhao Ying;Chen Fei(School of Safety Engineering,Beijing Institute of Petrochemical Technology,Beijing 102617,China;Insti-tute for Advanced Materials and Technology,University of Science and Technology Beijing,Beijing 100083,China;School of Materials Science and Engineering,Beijing Institute of Petrochemical Technology,Beijing 102617,China;Beijing Key Laboratory of Specail Elastomer Composites Materials,Beijing Institute of Petrochemical Tech-nology,Beijing 102617,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2022年第12期1580-1588,共9页
Chinese Journal of Rare Metals
基金
北京市自然科学基金项目(2202017)资助。
关键词
铝合金
阳极氧化
超疏水
耐腐蚀性能
aluminum alloy
anodic oxidation
corrosion resistance
superhydrophobic
