摘要
为了实现复合材料表面涂层划痕的多点自修复,研究多级管径的修复剂输送系统。在涂层中分别布置了主管道、次级管道以及末端微纳/多孔结构,构成多级微脉管修复剂输送系统。研究发现三级微脉管输送系统输送修复剂的效果最好,修复剂扩散更为均匀,扩散速度更快;主级管道水平布置更为合理,管道不易堵塞,修复剂输送更流畅,而且将主级管道嵌入基体中,可以减少其对涂层性能的影响。对末级管道结构的进一步研究表明,导流网结构比多孔泡沫镍的输送效果更好。因此,使用将主管道水平嵌入基体,末端微纳结构使用导流网的三级微脉管系统有望应用于复合材料表面涂层划痕的自修复。
材料自修复技术可以延长材料的使用寿命,避免突然失效造成损失、减少成本。自修复技术通常通过预埋微胶
管道的设计与制备对修复效果的影响至关重要,MOTUKU等
为了解决一维管道存在的不足,WILLIAMS等
三维微脉管网络更接近人和动物血管结构,如

(a) 动物皮肤表层血管

(b) 双油墨直写互穿网络
图1 三维微脉管网络
Fig.1 3D microvascular network
针对修复剂不能长期保存的问题,有人提出了通过外部加压输送的方法。WHITE
人和动物体的血管系统不仅是三维结构,而且血管管径有大小之分,既能保证血液的流量,又能保证血液与体表皮肤细胞结构的有效联通。表皮的毛细血管结构还能避免破损处失血过多。因此,本文立足三维结构,研究了多级管径微脉管修复剂输送系统,将微脉管与微纳结构相结合,构建用于表面涂层的多级输送系统,采用将涂层表面划伤后进行修复的方式,对输送系统进行优化。
选用环氧底漆和聚氨酯面漆组成实验试样的涂

(a) 泡沫镍

(b) 导流网
图2 末级管道结构图片
Fig.2 Final pipeline structure picture
为了取得良好的修复剂输送效果,对不同管道材料和管道放置方式进行了研究。如
如
采用玻璃管、铜管、硅胶管三种材料作为微脉管的材料,其中铜管的内径/外径:0.8/1.2 mm;玻璃管的内径/外径:0.9/1.1 mm;硅胶管的内径/外径:0.9/1.8 mm。末级微纳/多孔结构的材料为导流网和泡沫镍。

(a) 一级微脉管系统

(b) 二级微脉管系统(竖直主管道)

(c) 二级微脉管系统(水平主管道)

(d) 三级微脉管系统

(e) 三级微脉管系统(主管道嵌入基体)
图3 多级微脉管系统结构示意图
Fig.3 Sketch map of multi-diameter microvascular system,
确定了微脉管的材料后,制作三组7个试样。
第一组为一级管道修复系统,包含试样
第二组为二级微脉管修复系统。试样
第三组为三级输送系统,主管道使用了铜管和玻璃管。试样
修复剂输送管道布置完成后,涂上聚氨酯底漆,放置12 h,待底漆完全固化后,涂上聚氨酯面漆。为了使得漆面分布均匀,聚氨酯面漆分三次涂上。每次涂完,放入干燥箱中85 ℃加热30 min,待漆面完全干燥,再进行下一步涂刷。到此试样制备完成。
将制备好的试样,参照D.M.Kim
一级微脉管输送系统的试样在涂层下方只存在主级微管道。主级微管道尺寸较大,为了减少对涂层的影响,主级管道布置比较稀疏。如

图4 一级微脉管扩散原理图
Fig.4 Schematic diagram of primary microvasculature diffusion
实验结果如

(a) 试样

(b) 试样
图5 一级微脉管试样自修复结果
Fig.5 Self-healing results of samples with primary diameter microvascular
二级微脉管输送系统包括主级微管道与末级微纳/多孔结构。由于末级微纳/多孔结构的存在,修复剂从主级管道流入后,经末级管道流至损伤区域。导流网可以覆盖整个试样,修复原理如

(a) 竖直主管道

(b) 水平主管道
图6 二级微脉管系统修复剂输送原理图
Fig.6 Schematic diagram of repair agent delivery of two-diameter microvasculature system
试样

(a) 试样

(b) 试样

(c) 试样
图7 二级微脉管试样自修复结果
Fig.7 Self-healing results of samples with two-diameter microvascular
三级微脉管输送系统包括主级管道,次级微管道和末级微纳结构。基于二级脉管输送系统的实验结果,末级微纳结构使用导流网的扩散效果更好。试样
如

图9 三级微脉管系统修复剂输送原理图
Fig.9 Schematic diagram of healing agent delivery in three-diameter microvasculature system

(a) 试样

(b) 试样
图8 三级微脉管试样自修复结果
Fig.8 Self-healing results of samples with three-diameter microvascular
针对复合材料表面涂层自修复问题,研究多级管径微脉管的修复剂输送系统,根据修复剂在涂层表面缝隙的渗透与铺展行为,对管道结构、管道布置、管道材料等开展了研究。对单级管径管道系统、二级管径管道系统以及三级管径管道系统的研究表明:
(1)三级微脉管输送系统输送修复剂的效果最好,修复剂从主管道通过次级微管道流向导流结构的末级结构,修复剂扩散更为均匀,扩散速度更快;
(2)主级管道水平布置比垂直布置效果更好,修复剂输送更顺畅,管道不易堵塞,主级微管道嵌入基体与铺放在涂层中相比,修复效果无明显差别,但是将主级微管道潜入基体,可以减少其对涂层性能的影响;
(3)对末级管道结构的研究表明,导流网结构比多孔泡沫镍的输送效果更好,可以取得更好的修复效果。次级管道可以根据连接主管道与末级管道结构的需要,采取在主管道上开槽或者向预埋在试样基体中的管道钻孔的方式,形成不同长度/深度的次级管道。
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