单晶硅激光原位辅助塑性切削与低损伤加工机理研究

Monocrystalline silicon has the characteristics of high refractive index, small dispersion and high transmission in infrared band. It is widely used in the fields of national defense industry such as advanced infrared detection system and high-tech weapons. Laser in-situ assisted single point diamond cutting technology is expected to solve the difficult problem of ultra-precision cutting of monocrystalline silicon with high efficiency. But the core scientific problems of plastic cutting mechanism and low damage machining mechanism of materials involved in this technology are still unresolved. In this project, reconstruction of temperature field and optimization of process parameters, ductile cutting mechanism of monocrystalline silicon, surface/subsurface damage behavior and mechanism in laser in-situ assisted diamond cutting are investigated by transmission electron microscopy, Raman spectroscopy, molecular dynamics simulation and smooth particle fluid dynamics simulation. The brittle-ductile transition theoretical model for the deformation behaviors of the monocrystalline silicon and the distribution theoretical model of the subsurface strained layer are established. Moreover, the ductile removal mechanism of monocrystalline silicon and the subsurface strain energy dissipation mechanism during the cutting process are explored using the theory of crystal slip and dislocation movement, which is finally aim to reveal the low damage mechanism in laser in-situ assisted cutting. The research results of this project can provide theoretical guidance and technical support for the efficient and high-quality processing of monocrystalline silicon infrared optical elements.

单晶硅具有折射率高、色散小、红外波段透射率高等特性，广泛应用于先进红外探测系统与高端武器装备等国防工业领域。激光原位辅助单点金刚石切削技术有望解决单晶硅的高效超精密切削加工难题，但该技术所涉及的材料塑性切削机理与低损伤加工机理等核心科学问题仍未解决。本项目采用透射电子显微镜、拉曼光谱、分子动力学仿真及光滑粒子流体动力学仿真等技术手段，开展激光原位辅助切削温度场重构与工艺优化，阐明单晶硅激光原位辅助塑性切削机理与亚表层损伤行为及机理；构建温度诱发单晶硅脆-塑转变的理论模型与加工亚表面应变层的分布模型；运用晶体滑移与位错运动理论，阐明单晶硅的塑性去除机理与亚表层应变能的耗散机制，揭示激光原位辅助切削的低损伤机理。本项目的研究成果能够为单晶硅红外光学元件的高效高质量加工提供理论指导与技术支撑。

单晶硅具有折射率高、色散小、红外波段透射率高等特性，广泛应用于先进红外探测系统与高端武器装备等国防工业领域。激光原位辅助单点金刚石切削技术有望解决单晶硅的高效超精密切削加工难题，但该技术所涉及的材料塑性切削机理与低损伤加工机理等核心科学问题仍未解决。本项目采用透射电子显微镜、拉曼光谱、分子动力学仿真及光滑粒子流体动力学仿真等技术手段，开展激光原位辅助切削温度场重构与工艺优化，阐明单晶硅激光原位辅助塑性切削机理与亚表层损伤行为及机理；构建温度诱发单晶硅脆-塑转变的理论模型与加工亚表面应变层的分布模型；运用晶体滑移与位错运动理论，阐明单晶硅的塑性去除机理与亚表层应变能的耗散机制，揭示激光原位辅助切削的低损伤机理。.激光原位辅助单点金刚石切削技术与传统的单点金刚石切削技术的对比实验结果表明，激光原位辅助单点金刚石切削技术可以通过软化作用降低材料的硬度和促进次表层中的原子活动来提高硅的延展性和可加工性。建立的温度场模型可以精准预测激光辅助作用下切削区域温度分布，用于指导工艺参数的选择；激光原位辅助切削技术的临界切削深度增加了高达364%，并且其促进程度一般随着温度的升高而增加，摩擦系数降低了27.95%。透射电子显微镜观察结果表明，激光原位辅助切削技术能够有效抑制畸变层的形成，对单晶硅产生较小的亚表面损伤。与传统单晶硅单点金刚石车削相比，激光原位辅助切削获得了表面质量的显着改善：Sz降低了87%，Sa降低了50%。温度升高促进了位错的运动与变形区材料的解理剪切，工件内部的塑性变形区范围有所扩大，同时在切屑中形成了更多的微晶粒。基于不同温度下的切削模拟研究了激光热场对切削表面形貌和去除过程的影响；通过变形与再结晶模拟揭示了高温作用下非晶硅的自润滑与缺陷修复规律；通过微激光辅助变切深切削实验验证了非晶的自润滑与再结晶效应。本项目的研究成果能够为单晶硅红外光学元件的高效高质量加工提供理论指导与技术支撑。