钛合金表面化学转化膜的制备及成膜机理研究

发布时间：2018-05-23 10:59

  本文选题：钛合金 + 结合力　； 参考：《南昌航空大学》2015年硕士论文

【摘要】：本文针对钛合金与有机涂层结合性能差的问题,研究了钛合金表面化学转化膜的制备工艺。根据选定的转化液基础配方,以转化膜膜重、转化膜与漆膜的结合力为评价指标,采用正交试验及单因素试验对转化液成分、转化工艺进行了优化;通过电位-时间曲线对转化膜生长过程进行了研究;在钛合金化学转化过程中,以转化液中磷酸根离子和氟离子的消耗量为指标调整转化液;采用SEM、EDS、XRD研究分析化学转化膜的表面形貌和成分,结果表明:在Na3PO4·12H2O 40 g/L,NaF 20 g/L,酸度调节剂25mL/L,p H值4.4~4.8,温度30℃条件下,对TC1钛合金转化处理6min,对TC4钛合金转化处理8min可以分别在其基体上获得一种灰黑色均匀的膜层,该化学转化膜经过100℃烘干处理30min后可进一步提高其与漆膜的结合力。测试结果表明:TC1、TC4钛合金化学转化膜试样与航空常用漆TB06-9底漆干法结合力、湿法结合力分别达到0级、1级;TC1、TC4钛合金表面化学转化膜试样分别通过了120h、144h盐雾实验;TC1化学转化膜试样的含氢量较基体增加了25.86 ppm,TC4增加了4.28ppm,二者均小于30ppm,满足钛合金零件使用规定;该化学转化工艺处理不会损伤钛合金的疲劳性能,甚至还略有提高。本文确定了连续加工过程中化学转化槽液中主要成分PO43-、F-、总酸度及Ti4+的分析及补加方法,并进行了生产验证。Na3PO4、Ti4+含量变化均可通过分光光度法测定;NaF浓度变化可采用直接电位法分析;总酸度变化可以通过酸碱滴定法确定。电位-时间曲线表明:转化45s之后转化液中Ti4+浓度上升到转化膜生长所需浓度,转化膜开始生长;随着Ti4+的消耗生长速度开始下降,600s后膜层生长溶解达到平衡,膜层不再生长,这与测试得到的膜层生长速率曲线相符合。SEM结果表明:钛合金化学转化膜由许多细小的球状晶粒组成,膜层结晶均匀、晶粒大小相近,同时晶粒之间存在微小的间隙。此结构既能保证膜层具有良好的表面形态,同时微间隙的存在有助于提高化学转化膜与漆膜的结合力;XRD结果显示:转化膜出现了大量的Na3TiOF5相和Na2TiF6相,且Na3TiOF5相衍射峰的数量和峰值高于Na2TiF6相,即膜层中Na3TiOF5相含量略高。
[Abstract]:In order to solve the problem of poor bonding property between titanium alloy and organic coating, the preparation process of chemical conversion film on titanium alloy surface was studied in this paper. According to the basic formula of conversion liquid, the composition and process of conversion solution were optimized by orthogonal test and single factor test, with the weight of conversion film and the binding force of conversion film and paint film as evaluation index. In the process of chemical transformation of titanium alloy, the consumption of phosphate ion and fluorine ion in the transformation solution was taken as the index to adjust the conversion solution. The surface morphology and composition of the chemical conversion film were studied by means of Na3PO4 12H2O EDSX XRD. The results showed that under the conditions of Na3PO4 12H2O 40 g / L NAF 20 g / L, acidity regulator 25 mL / L P H 4. 4 4. 8 and temperature 30 鈩，

本文编号：1924451