Luo Haoqi, Wang Xue, Qin Lin, Zhao Hongxin, Zhu Deqing, Ma Shanyi, Zhang Jianguo, Xiao Junfeng
State Key Laboratory of Intelligent Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
Beijing Precision Engineering Institute for Aircraft Industry, Aviation Industry Corporation of China, Beijing 100076, China.
Micromachines (Basel). 2024 Oct 21;15(10):1275. doi: 10.3390/mi15101275.
Polycrystalline ZnS is a typical infrared optical material. It is widely used in advanced optical systems due to its excellent optical properties. The machining accuracy of polycrystalline ZnS optical elements must satisfy the requirements of high-performance system development. However, the soft and brittle nature of the material poses a challenge for high-quality and efficient machining. In recent years, in situ laser-assisted diamond cutting has been proven to be an effective method for ultra-precision cutting of brittle materials. In this study, the mechanism of in situ laser-assisted cutting on ultra-precision cutting machinability enhancement of ZnS was investigated. Firstly, the physical properties of ZnS were characterized by high-temperature nanoindentation experiments. The result revealed an increase in ductile machinability of ZnS due to plastic deformation and a decrease in microhardness and Young's modulus at high temperatures. It provided a fundamental theory for the ductile-brittle transition of ZnS. Subsequently, a series of diamond-cutting experiments were carried out to study the removal mechanism of ZnS during in situ laser-assisted cutting. It was found that the mass damage initiation depth groove generated by in situ laser-assisted cutting increased by 57.99% compared to the groove generated by ordinary cutting. It was found that micron-sized pits were suppressed under in situ laser-assisted cutting. The main damage form of HIP-ZnS was changed from flake spalling and pits to radial cleavage cracks. Additionally, the laser can suppress the removal mode difference of different grain crystallographic and ensure the ductile region processing. Finally, planning cutting experiments were carried out to verify that a smooth and uniform surface with Sa of 3.607 nm was achieved at a laser power of 20 W, which was 73.58% better than normal cutting. The main components of roughness were grain boundary steps and submicron pit. This study provides a promising method for ultra-precision cutting of ZnS.
多晶硫化锌是一种典型的红外光学材料。由于其优异的光学性能，它被广泛应用于先进光学系统中。多晶硫化锌光学元件的加工精度必须满足高性能系统开发的要求。然而，该材料的软脆特性给高质量、高效率加工带来了挑战。近年来，原位激光辅助金刚石切割已被证明是一种用于脆性材料超精密切割的有效方法。在本研究中，对原位激光辅助切割提高硫化锌超精密切割加工性能的机理进行了研究。首先，通过高温纳米压痕实验对硫化锌的物理性能进行了表征。结果表明，由于塑性变形，硫化锌的延性加工性能有所提高，且在高温下显微硬度和杨氏模量降低。这为硫化锌的延性-脆性转变提供了基础理论。随后，进行了一系列金刚石切割实验，以研究原位激光辅助切割过程中硫化锌的去除机理。结果发现，原位激光辅助切割产生的质量损伤起始深度槽比普通切割产生的槽增加了57.99%。发现在原位激光辅助切割下微米级凹坑得到了抑制。热等静压硫化锌的主要损伤形式从片状剥落和凹坑转变为径向解理裂纹。此外，激光可以抑制不同晶粒晶体学的去除模式差异，并确保延性区域加工。最后，进行了规划切割实验以验证在20W激光功率下可获得表面粗糙度平均高度Sa为3.607nm的光滑均匀表面，这比普通切割提高了73.58%。粗糙度的主要成分是晶界台阶和亚微米级凹坑。本研究为硫化锌的超精密切割提供了一种有前景的方法。
