Generation mechanism of optical surface in ultra-precision cutting polycrystalline zinc selenide

• Published in: Applied surface science Vol. 676; p. 161005
• Main Authors: Zheng, Jiangfeng, Zhang, Guoqing, Zhang, Wenqi, Huang, Zejia, Lai, Zhihui
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2024
• Subjects: Cutting mechanism; Molecular dynamics simulation; Polycrystalline ZnSe; Surface defects; Ultra-precision cutting; Polycrystalline ZnSe; Molecular dynamics simulation; Ultra-precision cutting; Cutting mechanism; Surface defects
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2024.161005

[Display omitted] •The surface defects of polycrystalline ZnSe after ultra-precision cutting, such as irregular microstructure, micron scale craters and submicron scale pits, were observed.•The molecular dynamics simulation reveals that the pits are caused by the expansion of shear stress along grain boundaries and within grains.•Increasing the cutting speed can depress the formation of micron-craters and material rebound.•The use of the negative rake angle of the tool will bring burrs to the surface and affect the surface quality. Despite having an excellent infrared optical property, efficient material removal of zinc selenide (ZnSe) is yet to be realized and its defect generation mechanisms during ultra-precision cutting are not fully elucidated. In this study, ultra-precision cutting experiments on polycrystalline ZnSe were conducted by considering various cutting parameters and utilising surface topography, chip morphology, cutting force, and X-ray diffraction data to investigate its surface generation mechanisms, which were further augmented by molecular dynamics simulations to analyse the generation and suppression of surface defects. The results revealed the presence of irregular microstructures on the surface of polycrystalline ZnSe, arising from variations in material rebound owing to differing grain orientations, as well as micron-sized craters located at grain boundaries and submicron-sized pits within individual grains. Increasing the cutting speed facilitated instantaneous grain fractures, thus preventing grain peeling and effectively suppressing the generation of micron-sized craters and material rebound. Although the use of a negative rake angle on the tool suppressed the generation of micron-sized craters, it introduced a proliferation of burrs that was detrimental to the surface finish. These findings provide valuable insights for optimising the ultra-precision machining process and enhancing the surface quality of brittle polycrystalline ZnSe.