【作者】 李霞；

【导师】 李凌杰；

【作者基本信息】 重庆大学 ， 化学， 2020， 硕士

【摘要】 镁合金具有密度低、强度大、比强度高等特点,在汽车、电子、航天航空等领域具有广泛的应用。但是,镁合金化学性质非常活泼,极易发生腐蚀而影响其应用。近年来发展的超疏水、超疏油表面具有防腐蚀、自清洁等功能,不仅可以为镁合金提供防护作用,还能赋予其自清洁能力,有助于扩大镁合金的应用领域。然而,目前文献报道的镁合金超疏水、超疏油表面制备步骤复杂、对基底有选择性、无法实现大规模生产,特别是这些表面的耐久性不佳,严重影响镁合金的应用。为解决上述问题,本论文采用简便的一步喷涂法在镁合金表面制备了具有良好耐久性的聚甲基丙烯酸甲酯/硬脂酸锌(PMMA/Zn(C₁₇H₃₅COO)₂)超疏水涂层和磷酸铝/全氟辛基三氯硅烷（AP/PFOTS）超疏水超疏油的超双疏涂层。利用接触角测量仪（CA）、扫描电子显微镜（FESEM）、X射线光电子能谱（XPS）和傅里叶红外光谱（FTIR）分别表征了涂层的润湿性、微观形貌和化学组成。通过实验室模拟实验和实际自然环境实验测试了涂层的防腐蚀性能、机械性能、化学稳定性能、光稳定性能、耐高温性能、自然环境适应性和自清洁性能。综合各项性质表征和性能测试结果,讨论了涂层的成膜机理和耐久性机制。主要工作如下:1、基于聚甲基丙烯酸甲酯（PMMA）可形成网状结构、硬脂酸（SA）处理后的Zn O可提供粗糙度且降低表面能的思想,通过喷涂PMMA/Zn(C₁₇H₃₅COO)₂喷涂液在镁合金表面制备了超疏水涂层,其静态接触角为157.0°、滚动角为6.0°。涂层由紫菜状的微纳米结构组成,其主要成分为PMMA和硬脂酸锌。涂层中硬脂酸锌的长烷基链(C₁₇H₃₅-)能够显著降低涂层的表面能,使涂层具有超疏水性。性能测试结果表明,所制备的涂层具有优异的防腐蚀性（R_c=1.23×10⁵Ω·cm²）、自清洁性、耐砂粒冲击性(1.0 g min^-1,≥20 min)、耐水冲击性（2滴每秒,≥180 min）、耐摩擦磨损性（1.0 k Pa,≥1250 cm）、耐胶带剥离性（≥2.15 k Pa）、耐酸碱性（p H=1～13）、耐有机溶剂浸泡（≥24 h）和耐高温性能（200°C,≥24 h）。硬脂酸锌嵌入聚合物PMMA形成的网状结构中,被牢牢固定,因此涂层表现出良好的耐久性。2、基于磷酸铝（AP）在一定温度下可与镁合金反应形成微/纳米结构的同时增强涂层与基底的结合力、低表面能物质全氟辛基三氯硅烷（PFOTS）可提供极低表面能的思想,通过喷涂AP/PFOTS喷涂液在镁合金表面制备了超疏水、超疏油的超双疏涂层,该涂层对水及表面张力小于35.3 m N m^-1的油都具有超疏性。涂层呈多层网络结构且网络结构上分布着许多纳米突起,涂层中的含氟官能团赋予涂层极低的表面能。性能测试结果表明,所制备的涂层具有优异的耐砂粒冲击性(1.0 g min^-1,≥20 min)、耐水冲击性（2滴每秒,≥20 h）、耐摩擦磨损性（1.0 k Pa,≥2500 cm）、耐酸碱性（p H=1～14）、耐有机溶剂浸泡（≥48 h）和光稳定性（≥672h）,自然环境测试进一步表明该涂层具有良好的环境适应性。涂层对无机颗粒和有机物的污染均具有持久的自清洁性能。由于没有额外添加纳米颗粒,涂层完整均匀,磷酸铝自身的胶黏性质及其与镁合金基底反应增强了涂层与基底的结合力,使得涂层具有优异的耐久性。更多还原

【Abstract】 For their low density,high strength and high specific strength,magnesium alloys are widely used in automotive,electronics,aerospace and other fields.However,the chemical property is so active that the application seriously compromised because of their high susceptibility to corrosion.The superhydrophobic and superoleophobic surfaces developed in recent years have the functions of anti-corrosion and self-cleaning property,which can not only provide protection for magnesium alloys,but also endow them with self-cleaning ability,which helps to expand the application field of magnesium alloys.However,the superhydrophobic and superoleophobic surfaces of magnesium alloys reported in the current literature have complicated preparation processes,substrate-dependence,and small-scale production.In particular,the poor durability of these surfaces seriously affects the application of magnesium alloys.In order to solve the above problems,in this paper,a simple one-step spray method was used to prepare a polymethyl methacrylate/zinc stearate(PMMA/Zn(C₁₇H₃₅COO)₂)superhydrophobic coating and aluminum phosphate/perfluorooctyl trichlorosilane（AP/PFOTS）superamphiphobic coating with superhydrophobicity and superoleophobicity on the surface of magnesium alloys with good durability.The wettability,micro-morphology and chemical composition of the coating were characterized by contact angle measuring instrument（CA）,scanning electron microscope（FESEM）,X-ray photoelectron spectroscopy（XPS）and Fourier infrared spectroscopy（FTIR）.The anti-corrosion performance,mechanical performance,chemical stability,light stability,high temperature resistance,natural environment adaptability and self-cleaning performance of the coating were tested through laboratory simulation experiments and actual natural environment experiments.Based on the characterization of various properties characterization and performance test results,the film formation mechanism and durability mechanism of the coating are discussed.And the main tasks as follows:1.Based on polymethyl methacrylate（PMMA）can form a network structure,Zn O modified with stearic acid（SA）can provide the idea of roughness and reduce surface energy,a superhydrophobic coating was prepared with a static contact angle of 157.0°and a rolling angle of 6.0°by spraying PMMA/Zn(C₁₇H₃₅COO)₂ suspension on the surface of magnesium alloys.The coating consists of laver-like micro-nano structures,whose main components are PMMA and zinc stearate.The long alkyl chain(C₁₇H₃₅-)of zinc stearate in the coating can significantly reduce the surface energy of the coating,making the coating superhydrophobic.Performance test results show that the prepared coating has excellent corrosion resistance（R_c=1.23×10⁵Ω·cm²）,self-cleaning property,sand impact resistance(1.0 g min^-1,≥20 min),water impact resistance（2drops per second,≥180 min）,friction and wear resistance（1.0 k Pa,≥1250 cm）,tape peel resistance（≥2.15 k Pa）,acid and alkali resistance（p H=1～13）,resistance to organic solvent immersion（≥24 h）and high temperature resistance（200°C,≥24 h）.Zinc stearate is embedded in the network structure formed by the polymer PMMA and is firmly fixed,so the coating shows good durability.2.Aluminum phosphate（AP）can react with magnesium alloys to form micro/nano structure at a certain temperature to enhance the binding force between the coating and the substrate,and perfluorooctyltrichlorosilane（PFOTS）can provide extremely low surface energy substance.Based on the above reasons,the superhydrophobic and superoleophobic coatings were prepared on the surface of magnesium alloys by spraying AP/PFOTS suspension The coating has a multi-layer network structure and many nano-protrusions are distributed on the network structure.The fluorine-containing functional groups in the coating give the coating extremely low surface energy.Performance test results show that the prepared coating has excellent impact resistance to sand particles(1.0 g min^-1,≥20 min),water impact resistance（2 drops per second,≥20 h）,and friction and wear resistance（1.0 k Pa,≥2500 cm）,acid and alkali resistance（p H=1～14）,resistance to organic solvent immersion（≥48 h）and light stability（≥672 h）,and natural environment testing further shows that the coating has good environmental adaptability.The coating has long-lasting self-cleaning performance on the pollution of inorganic particles and organic matter.Without additional nanoparticles adding,the coating is complete and uniform.The adhesive property of aluminum phosphate and the reaction with the magnesium alloy substrate enhanced the bonding force between the coating and the substrate,making the coating have excellent durability.更多还原