Acta Photonica Sinica, Volume. 52, Issue 4, 0414002(2023)

Complex Coupling Model and Morphology Effect of Femtosecond Laser Ablation of Tooth Surface

Xingzu MING1,2, Xuekun LI2、*, Chengji MI2, Guoqi HE2, Xian ZHOU1, Chao LI3, and Rui MING2、**
Author Affiliations
  • 1School of Mechanical Engineering, Hubei University of Arts and Science, Xianyang 441053, China
  • 2School of Mechanical Engineering, Hunan University of Technology, Zhuzhou 412007, China
  • 3Technology Center of Zhuzhou Gear Co., LTD., Zhuzhou 412000, China
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    The two-temperature model is commonly used to analyze the femtosecond laser ablation process, simulating laser ablation by analysing the coupling of electrons to the lattice and the temperature change. Due to the extremely short pulse width of the femtosecond laser, a variety of dynamic effects are generated during the ablation process, such as energy accumulation effects, defocusing effects and dynamic material absorption rate effects. Therefore, when studying the femtosecond laser ablation process, it is necessary to consider the effect of dynamic effects on the size of the ablation. The existing ablation models need to be improved to improve the efficiency of femtosecond laser processing and the accuracy of ablation models. In this paper, a quantitative relationship between the variation in the number of pulses and the total laser energy absorbed by the material is established for the energy accumulation effect; the laser energy at different ablation depths is also obtained based on the effect of the variation in ablation depth on the laser focus radius. By coupling the energy accumulation effect and the defocusing effect into the dual-temperature model, the temperature distribution of the electrons and lattice of the laser-ablated surface gear material 18Cr2Ni4WA is obtained by the finite difference method at different pulse widths and energy densities. The temperature at equilibrium is around 3 000 K, which reaches the cavitation temperature of the face gear material 18Cr2Ni4WA, and the material can be ablated, and the depth and radius of the ablation crater are 4.07 μm and 24.23 μm, respectively.Considering that the surface of the material processed by the femtosecond laser is mostly a complex curved surface, the angle between the laser beam and the surface to be processed during the processing of the curved material will change due to the vertical writing of the laser beam. The laser beam is tilted to ablate the surface of the material and only the laser component perpendicular to the material surface acts on the microstructure of the material surface. Therefore, it is necessary to establish quantitative relationships between the refractive index of the laser beam and the tilt angle, as well as between the focus radius and the tilt angle, to analyze the effect of the tilt angle between the laser beam and the machined surface on the size and shape of the machined surface when the laser beam is ablated on curved materials. The simulations show that the effective laser intensity decreases significantly after the tilt angle between the laser beam and the material being processed exceeds 40°. The laser spot is elliptical on the surface of the material. Finally, it was experimentally verified that when the laser energy density was 1.783 J/cm2 and the bottom angle of the machined tooth surface was too large, the ablation process only occurred on the surface of the material; when the energy density was 2.376 J/cm2 and the number of laser pulses was 3 000, the microstructure of the ablation crater was good and fine. The results show that the laser energy decreases with the change in tilt angle when the surface is ablated by the femtosecond laser, while the energy distribution of the laser spot affects the change in the depth of the ablation crater.

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    Xingzu MING, Xuekun LI, Chengji MI, Guoqi HE, Xian ZHOU, Chao LI, Rui MING. Complex Coupling Model and Morphology Effect of Femtosecond Laser Ablation of Tooth Surface[J]. Acta Photonica Sinica, 2023, 52(4): 0414002

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    Paper Information

    Category:

    Received: Aug. 7, 2022

    Accepted: Oct. 27, 2022

    Published Online: Jun. 21, 2023

    The Author Email: LI Xuekun (1281855580@qq.com), MING Rui (844153340@qq.com)

    DOI:10.3788/gzxb20235204.0414002

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