宽频吸波材料多层次微纳结构的激光原位沉积机理及制造技术研究

A new generation wave-absorbing materials for invisibility cloak at short wavelengths is to be great application in fields of aeronautics and astronautics, defense military, and so on. To meet the ultra-broadband perfect absorption of visible-infrared-terahertz light, in this project, a new mulit-scale micro-nano structure is produced to improve the light-absorbing properties of the metal material: the structural characteristic of the mirco-nano structures in the X-Y plane is modified to widen the wave-absorbing spectrum of materials, and the nanoporous structure with various porosities and a sufficient thickness is formed on the surface of micro-nano structure, of which the combination can improve wide-band wave-absorbing efficiency of the material. To solve the problem of efficient high-quality manufacturing of the multi-scale micro-nano structures for extreme broadband antireflection performance, this project proposes a novel machining technology of in situ deposition using high-repetition-rate ultrafast laser, where the two processes of laser ablation and laser deposition are combined. This technology can realize the collaborative manufacturing of the “preparation of micro-nano structures by laser ablation” and “nanoporous structures deposition with high porosity”, and simplify the fabrication procedure of the multi-scale structures. As a result, it can be used to produce the ideal wave-absorbing structures on the surface of the component with all shapes and sizes, which breaks the bound of the limited manufacturing area in conventional laser deposition. This project will focus on the mechanism of the in situ material deposition under high-repetition-rate ultrafast laser irradiation, the regulation method for high-efficient production of multi-scale micro-nano structure, and the influence of structure characteristic on the wave-absorbing performance. This project aims to develop a novel multi-scale micor-nano structure forming method for ultra-broadband perfect light absorption, which is promising in promoting the development of the invisibility cloak at short wavelengths in our country.

开发面向短波长隐身的新一代吸波材料对于支撑航空航天、国防军事等发展至关重要。本项目针对金属材料“可见光-红外-太赫兹”宽频域高效吸波的需求，提出一种采用多层次微纳结构提升吸波性能的新思路：利用X-Y平面内的微纳复合结构拓宽材料的吸波频段；通过在微纳复合结构表面制备一定厚度的变孔隙率纳米多孔结构，提升宽频段内的吸波效率。为解决上述吸波结构的制造难题，本项目提出高重频超快激光原位沉积的新技术，该技术将激光加工与激光沉积过程合二为一，实现“微纳复合结构烧蚀”与“高孔隙率纳米多孔结构沉积”的协同制造，减少了多层次结构制造的流程，摆脱了常规沉积对制造面积的束缚，有望实现不同形状尺寸构件的大面积吸波结构制造。本项目将在超快激光原位沉积机理、多层次微纳结构调控方法、结构特征对吸波性能影响规律等三个方面探索基础理论，建立金属材料宽频吸波结构制造技术，获得性能优越的宽频吸波材料，推动我国短波长隐身领域发展。

宽频吸波硅材料在航空航天、国防军事、新能源等领域有着巨大的应用潜力。本项目针对硅材料“紫外-可见光-红外”宽频域高效吸波的需求，提出了一种采用飞秒激光制备多层次微纳结构提升硅材料表面宽频高效吸波的新思路：利用 X-Y 平面内的微纳复合结构拓宽材料的吸波频段；通过在微纳复合结构表面进一步诱导制备小尺寸微纳米结构或制备纳米多孔结构，提升宽频段内的吸波效率。为了完成上述结构制备的新思路，本项目提出了两种高效高质制备多层次微纳结构的新技术：空气中飞秒激光烧蚀与激光清洗诱导复合制造技术，解决了空气中激光加工因硅氧化难以获得宽频域优异吸波性能的多层次微纳结构难题；飞秒激光烧蚀/原位沉积协同制造技术，提高了多层次微纳结构的抗反射性能和制备效率。为了进一步提高飞秒激光烧蚀/原位沉积技术制备多层次微纳结构的效率，针对高重频飞秒激光加工中由于过度热累积导致微纳多孔结构团聚结核的问题，提出基体冷却辅助高重频飞秒激光高效加工新方法，在保持硅表面超低反射率的同时提高1.5-3倍的加工效率。最后，实验验证了多层次微纳结构具有高效的太阳能蒸馏淡化性能。