射流抛光中纳米颗粒碰撞的材料去除机理研究

The fabrication of ultra-smooth surfaces of aspherical components is a great challenge in the ultra-precision machining. The conventional polishing techniques are difficult to meet the requirements. The Fluid Jet Polishing (FJP) can polish complex curved surfaces and can obtain atomic-scale roughness and damage-free surface, and thus has been considered to be one of the most potential techniques for the ultra-smooth processing of aspherical surfaces. However, FJP still can not meet the processing requirements of the next-generation products due to its low material removal rate. Knowning the material removal mechanism of FJP is the key to solve the problem. This project is to establish the model for the collision between the nanoparticles and the polished surface in FJP by combining the direct observations on the collisions, the solid-liquid two phase flow theory, the surface physical chemistry, the nanotribology and the numerical techniques. Then, considering also the measurements of the material removal distribution on the polished surface, the effect of the nanoparticle-surface collision in FJP on the material removal will be studied, the microscopic material removal mechanism in FJP can be revealed, and the technologies and methods to improve the material removal rate and the surface quality can then be explored. The results can be useful to reveal the formation mechanism of the surface with high precision and without demage in the ultra-precision machining techniques, and thus has important scientific significance and academic value to establishing the processing theory of the nanoscale and sub-nanoscale ultra-smooth surfaces.

非球面元件的超光滑表面加工是目前超精密加工中面临的巨大难题,传统的抛光技术很难满足要求。由于能够加工复杂型面且可获得原子级粗糙度和无损伤表面，射流抛光（FJP）被认为是当前非球面超光滑加工最有潜力的技术之一。但目前的FJP技术仍存在去除率低等诸多问题，尚不能满足下一代产品的表面加工要求。充分了解FJP的微观材料去除机理是解决这一问题的关键。本课题从FJP中冲击射流流场以及纳米颗粒和加工表面碰撞的实验观测出发，结合固液二相流动理论、表面物理化学、纳米摩擦学和数值计算技术，建立FJP中纳米颗粒和工件表面的碰撞模型，并结合材料去除分布的测量，研究纳米颗粒对工件表面冲击的材料去除作用，进而阐明FJP中的微观材料去除机理，探索提高FJP去除率和表面质量的工艺和途径。本课题的研究对于揭示超精密加工技术中高精度无损伤表面的形成机理，建立纳米和亚纳米级超光滑表面加工理论具有重要的科学意义和学术价值。

非球面元件的超光滑表面加工是目前超精密加工中面临的巨大难题，传统的抛光技术很难满足要求。由于能够加工复杂型面且可获得原子级粗糙度和无损伤表面，射流抛光（FJP）被认为是当前非球面超光滑加工最有潜力的技术之一。但目前的FJP 技术仍存在去除率低等诸多问题，尚不能满足下一代产品的表面加工要求。充分了解FJP 的微观材料去除机理是解决这一问题的关键。本课题针对纳米颗粒碰撞的材料去除特性，将荧光技术与颗粒成像测速技术相结合，围绕射流中纳米颗粒运动、纳米颗粒-固体表面相互作用、液滴蒸发及颗粒沉积等科学问题，探索超光滑表面加工中的微观材料去除机制及后清洗过程。突破传统实验手段，成功研制了可用于射流中纳米颗粒运动、纳米颗粒-固体表面碰撞等观测的在线探测平台。进一步，在实验新平台的基础上，结合理论分析和数值计算，研究了射流中纳米颗粒的运动、碰撞规律，揭示了射流中纳米颗粒碰撞的材料去除机理，并对减少颗粒在抛光表面沉积进行了初步研究，可为射流抛光技术提供理论指导。