铝合金表面复合硅烷膜的制备及性能研究

发布时间：2018-02-07 13:44

  本文关键词： 硅烷偶联剂 复合硅烷膜 耐蚀性能 铈盐改性 杂化硅烷膜　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着社会对环境保护的重视,具有高度污染性的铬酸盐钝化处理技术正逐步退出铝合金表面处理的舞台,环境友好型的硅烷化处理技术应运而生,凭借其工艺简单、能耗低、处理液无毒性、膜层耐蚀性能高等一系列优点受到越来越多的关注。然而由于传统的硅烷膜功能单一、机械性能差、膜层不具备"自愈"能力,限制了硅烷化处理的应用发展。本实验针对传统硅烷化处理技术中存在的缺陷,在铝合金表面制备了复合硅烷膜并对其进行了一系列的表征测试;结合稀土转化膜的特点,实验选用硝酸铈铵改性复合硅烷膜,制备了具有一定自修复能力的杂化硅烷膜。本实验将两种性质不同的硅烷偶联剂KH560和PTMS进行复配,制备复合硅烷处理液。通过监测溶液水解过程中的电导率,采用控制变量法研究了不同因素对复合硅烷液水解过程的影响,并确定了处理液的最佳水解体系为甲醇用量15wt%、硅烷偶联剂浓度8wt%、水解液pH为6、水解温度30。℃。将达到水解平衡的硅烷液用于铝合金表面处理工艺中,通过对硅烷浓度、固化温度、成膜时间等条件进行优化,在铝合金表面制备一层复合硅烷膜层。对膜层进行耐蚀性和机械性能测试,结果表明:用KH560:PTMS为1:2的处理液在150℃高温下干燥1.5h后制备的复合硅烷膜性能最好。红外光谱测试揭示了复合膜层的形成机理,通过与不同膜层试样进行对比测试,直观评价了复合硅烷膜的综合性能,其中,在电化学测试中复合硅烷膜的腐蚀电流为1.641×10^-8A/cm2较单一膜层下降了 1个数量级、较氧化膜试样下降了 2个数量级,表明复合膜层试样的腐蚀速率最慢;接触角测试中复合膜层与水的接触角为92.5°,较其他试样具有更高的疏水性;而膜层表面SEM扫描图则表明复合硅烷膜层更加平整均匀。实验选用硝酸铈铵对复合硅烷膜进行改性,研究了硝酸铈铵的掺杂对成膜工艺带来的变化。结果表明:添加了 0.5g硝酸铈铵的复合硅烷处理液在180℃下固化1.0h后形成的杂化膜层综合性能最好。红外谱图中没有出现与铈相关的吸收峰,表明在成膜过程中硝酸铈铵不与硅烷偶联剂反应;杂化膜层的SEM扫描图中出现颗粒状物质,经EDS分析知颗粒物中含有Ce;XRD测试结果中出现铈的氧化物的吸收峰,表明在杂化膜成膜过程中硝酸铈铵铈以其氧化物的形式对硅烷膜进行了填充。将杂化膜层与硅烷膜层进行一系列的对比测试,直观的体现了硝酸铈铵的加入对膜层的各方面性能的提高,而盐雾试验则证明了杂化膜层所具有的自修复能力。
[Abstract]:With the attention of society to environmental protection, chromate passivation technology with high pollution is gradually withdrawing from the stage of aluminum alloy surface treatment. The environmentally friendly silane treatment technology emerges as the times require, with its simple process and low energy consumption. A series of advantages, such as non-toxicity of the treatment solution and high corrosion resistance of the film, have attracted more and more attention. However, due to the single function and poor mechanical properties of the traditional silane film, the film does not have the ability of "self-healing". In view of the defects of traditional silane treatment technology, the composite silane film was prepared on the aluminum alloy surface and a series of characterization tests were carried out, which combined with the characteristics of rare earth conversion film. Hybrid silane membranes were prepared by cerium ammonium nitrate modified composite silane membranes. In this experiment, two silane coupling agents, KH560 and PTMS with different properties, were prepared. By monitoring the conductivity of the solution during hydrolysis, the influence of different factors on the hydrolysis process of the composite silane solution was studied by the method of controlling variables. The optimum hydrolysis system was determined as follows: methanol dosage 15 wtt, silane coupling agent concentration 8 wt, hydrolytic solution pH 6, hydrolysis temperature 30.1 鈩，

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