Nanosecond Laser-Based High-Throughput Surface Nanostructuring (nHSN) and Process Mechanisms

该研究项目将研究激光和化学加工方法的基本原理，以在金属合金上创建功能表面纹理。制造的表面具有随机的微纳米级表面结构，可以促进超疏水（排斥水），并且具有高度抗反射特性，有利于减少阻力，防结冰，自清洁和光吸收应用。该加工方法可应用于许多关键工程材料，包括钢、铝、钛和镁合金，并提供能够处理大表面积的高通量工艺链。通过这种方法，激光加工时间将从目前要求的每6.5 cm^2（平方英寸）数百分钟大大减少到几秒钟。实现这些潜在的制造业收益将通过提高美国先进制造业的竞争力来促进国家的繁荣和福利，并将在包括航空航天、能源和国防在内的许多制造业领域得到应用。该奖项还将促进未来劳动力的培训，因为各级学生将获得先进制造和表面科学基础知识的经验。通过农村学者研究计划，将为来自爱荷华州农村地区的代表性不足的新生提供额外的教育机会。本项目的研究目标是了解驱动纳秒激光高通量表面纳米结构工艺的潜在基本机制。该工艺包括两个步骤：(1)水约束纳秒激光织构，在此过程中，高能纳秒脉冲激光扫描浸入水中的金属表面，使用大的空间增量和快速的处理速度；(2)化学浸泡处理，在此过程中，通过氯硅烷试剂浸泡进一步处理激光织构表面。具体任务有以下几个方面：1)验证增加的激光功率强度通过表面化学和微观结构变化产生所需的表面，2)验证化学蚀刻和化学浸泡处理过程中发生的表面硅化的竞争机制驱动纳米结构的形成，3)确定表面属性在高温、腐蚀性和/或磨蚀环境中的长期耐久性。4)确定随机表面纳米结构的尺寸、形状和变化对超疏水性、毛细附着力和抗反射特性的功能影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This research project will study the fundamentals of laser and chemical processing methods to create functional surface textures on metal alloys. The fabricated surfaces have random micro- and nanoscale surface structures that promote superhydrophobic (repels water), and highly anti-reflective characteristics that are favorable for drag reduction, anti-icing, self-cleaning, and light absorption applications. The processing method can both be applied to many critical engineering materials including steel, aluminum, titanium and magnesium alloys, and offer a high-throughput process chain capable of treating large surface areas. By this method, the laser processing time will be significantly reduced from hundreds of minutes per 6.5 cm^2 (square inch), as currently required, to a few seconds. Realization of these potential manufacturing gains will advance the national prosperity and welfare by increasing U.S. advanced manufacturing competitiveness, and will find application across many manufacturing sectors including aerospace, energy, and defense. The award will also facilitate training of the future workforce as students across all levels will gain experience in advanced manufacturing and surface science fundamentals. Additional educational opportunities will be made available for underrepresented freshman from rural areas of Iowa through the Rural Scholar Research Program.The research objective of this project is to understand the underlying fundamental mechanisms driving the nanosecond Laser-based High-throughput Surface Nanostructuring process. The process comprises two steps: (1) water-confined Nanosecond Laser Texturing, during which a high-energy, nanosecond pulse laser scans a metal surface submerged in water, using a large spatial increment and a fast processing speed: and (2) Chemical Immersion Treatment, during which the laser-textured surface is further treated by immersion in a chlorosilane reagent. Specific tasks are aimed at the following; 1) verifying that the increased laser power intensity generates the desired surfaces via surface chemistry and microstructural changes, 2) verifying that the competing mechanisms of chemical etching, and surface silianization occurring during the chemical immersion treatment drive the formation of the nanostructures, 3) determining the long-term endurance of surface attributes in high-temperature, corrosive, and/or abrasive environments, and 4) identification of the functional effects of random surface nanostructure size, shape and variation on superhydrophobicity, capillary adhesive forces, and anti-reflection characteristics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.