Research on the hydrophobicity properties of metal materials by ultrashort laser pulses modification

在材料科学和工程中湿润性能是材料表面的一个重要因素。由于在机械润滑、摩擦、面料染色、绘画等方面的良好应用前景，关于材料表面湿润性能调控的研究越来越引起人们的注意。表面的湿润性能依赖于材料表面的化学构成和微观形貌两个因素。目前有很多方法可以调控材料表面湿润性能，比如相分离、化学气相沉积、软刻蚀、阳极氧化和电沉积等。上述的方法都有各自的优点，但它们都有不足之处。一方面，这些工艺流程耗时长、成本高。另一方面，这些方法不能实现空间选择性加工。 本论文的目的是提供一种超短脉冲激光诱导金属材料表面微纳结构从而调控金属疏水性能的方法。通过利用超短脉冲激光与金属表面等离子激元相互干涉，在金属材料表面诱导出周期性结构，从而改变金属表面的粗糙度，来调控金属的疏水性能。本文的工作以及所取得的主要成果分为如下两个方面： 1、 利用超短脉冲激光直写方法成功实现金属材料从亲水性能到疏水性能的转变。通过使用皮秒光纤激光器在不锈钢表面进行直写，诱导出微纳结构，成功将不锈钢表面的接触角从88度增加到105度，实现不锈钢材料从亲水性能到疏水性能的转变。 2、 提出一种新的超短脉冲激光调控金属表面湿润性能的方式。在金属上面放置高分子聚合物材料，通过超短脉冲激光聚焦到两种材料的交界面，将上层的高分子聚合物材料写到下层的金属材料上，同时实现材料表面能的改变和微纳结构的形成。The wettability of materials is one of key characters in materials science and engineering. As its application has bearing in many areas such as machinery lubrication, friction, fabric dyeing and painting, research on modification of the wettability of material surfaces has received much attention. Previous studies indicate that the wettability of material surfaces depends on the chemical composition and micro-geometry on the surface. There are several methods that can modify surface wettability, such as phase disengagement, chemical vapor deposition, soft etching, anode oxidation and electrodeposition. These methods have their own advantages, however, they also have shortages. On the one hand, these processes have the character of long period and high cost. On the other hand, these methods can not achieve the space selective processing. This thesis aims to provide an approach to modifying the wettability of metal surfaces by ultrashort laser pulses induced micro-/nano-structures. Through the interference between the ultrashort laser pulses and surface plasmon polaritons on metal surfaces, micro-/nano-structures can be fabricated, thus, changing the roughness on the metal surface, realizing the modification of wettability. The main research results are summarized as follows: 1. The transformation from hydrophilicity to hydrophobicity on metal surfaces are realized by ultrashort laser pulses direct writing method. By picosecond laser pulses irradiating stainless steel surfaces directly, micro-/nano-structures can be formed on stainless steel surfaces, contributing to the increase of contact angle from 88° to 105°, which realizes a transformation from hydrophilicity to hydrophobicity. 2. A new approach has been proposed by which the wettability of metal surfaces can be modified. Through placing polymer materials on metal surfaces, when the ultrashort laser pulses focus on the interface between metal and polymer materials. The molecule of the polymer materials will be adhered to metal surface, realizing the change of surface energy and the fabrication of micro/nano structures