纳秒激光制备超疏水铝合金表面及液滴热弹跳行为研究

Study on Nanosecond Laser Fabrication of Superhydrophobic Surface on Aluminum Alloy and Thermal Bounce Behavior of Droplets

  • 摘要: 金属材料超疏水表面制备近年来引起了高度关注。在本研究中,采用纳秒激光技术制备具有螺旋状微米脊状结构的6061铝合金超疏水表面,对液滴在该表面上的接触角和滚动角进行测量,并结合格子玻尔兹曼数值模拟方法对液滴在该表面上的热弹跳行为进行研究。结果表明,样品的刻蚀深度随激光扫描速度的增大而减小;液滴在未经氟化处理的螺旋状微米脊状结构表面上的接触角约为7°,该表面呈超亲水性,在氟化处理后的螺旋状微米脊状结构表面上的接触角约为150°,该表面呈超疏水性;液滴在扫描速度较低与较高时制备的螺旋状微米脊状结构表面的滚动角分别约为(7±2)°与(33±1)°,不同激光扫描速度使铝合金表面具有了不同的黏附性;液滴在刻蚀深度较大的样品表面更容易发生热弹跳,这是因为此时液滴与热表面接触后的汽化作用在液滴下方产生了更大的向上压力,推动液滴出现连续弹跳。

     

    Abstract: In recent years, fabrication of superhydrophobic surfaces on metallic materials has attracted increasing attention. In this study, 6061 aluminum alloy superhydropholic surface with spiral micron ridge structure is fabricated by using the nanosecond laser processing method. The contact and roll angles between the droplets and surfaces are measured, and combined with the lattice Boltzmann simulation method, the thermal bounce behavior of droplets on the spiral micron ridge structure is investigated. The results show that the etching depth of the sample decreases with the increase of scanning speed. The contact angle between the droplet and surface with the spiral micron ridge structure and no fluoridation is about 7°, indicating that the surface has super hydrophilicity; the contact angle between the droplet with spiral micron ridge structure and fluoridation is about 150°, indicating the surface has superhy drophobicity. The roll angles between the droplets and spiral micron ridge structures prepared at low and high scanning speeds are about (7±2)° and (33±1)° respectively. Different scanning speeds make the aluminum alloys have different adhesiveness. The droplets are more likely to undergo thermal bouncing on the surface having a larger etching depth because the vaporization of the droplet after contacting with the hot surface generates a greater upward pressure underneath the droplet, pushing the droplet to bounce continuously.

     

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