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<p>This study focuses on the field of aero - engines. Nanosecond lasers are employed to machine film cooling holes (FCHs) on DZ40M cobalt - based superalloys with or without thermal barrier coatings (TBCs). The ablation mechanisms of different combinations of laser frequencies and energies are explored through a combination of simulation and experiments. A two-dimensional axisymmetric model was constructed to simulate the single - pulse ablation process. It was found that in the initial stage of laser irradiation, the energy density at the center of the laser spot was high, causing the material to rapidly heat up and vaporize. Heat diffused both longitudinally and transversely over time, expanding the heat affected zone. After the laser irradiation ceased, the surface temperature of the material dropped sharply, and heat was mainly conducted longitudinally. Under different parameter combinations, the material was mainly removed through continuous vaporization at high frequency and low energy (<i>f</i> = 500&#xa0;kHz, <i>E</i> = 0.4&#xa0;mJ). A mixed mechanism of central vaporization and peripheral melting occurred at medium frequency and medium energy (<i>f</i> = 250&#xa0;kHz, <i>E</i> = 0.8&#xa0;mJ). Heat diffusion, molten pool flow, and material redeposition were promoted at low frequency and high energy (<i>f</i> = 50&#xa0;kHz, <i>E</i> = 1.6&#xa0;mJ). Experiments indicated that different parameters had various effects on FCHs. Medium frequency and medium energy conditions were likely to generate cracks and melt accumulation, while low frequency and high energy conditions severely ablated the TBC structure. The material removal mechanisms mainly included vaporization, melting, shock waves, and melt injection. The dominant mechanisms differed under different parameters. The vaporization dominated at high frequency and low energy. The molten material was ejected and resolidified at the orifice at medium frequency and medium energy. The shock wave effect was significant at low frequency and high energy.</p>

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Effect of Laser Frequency and Energy on the Film Cooling Holes Drilling Process of Cobalt-Based Superalloys with Thermal Barrier Coating for Aircraft Engine Blade

  • 期刊论文

  • 发表日期：

    2025年5月29日

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  • Jiecai Feng,
  • Chengpeng Qie,
  • Taili Chen,
  • Hongfei Liu,
  • Yilian Zhang,
  • Shijin Zhang,
  • Lin Yuan,
  • Yingzhong Tian

摘要

This study focuses on the field of aero - engines. Nanosecond lasers are employed to machine film cooling holes (FCHs) on DZ40M cobalt - based superalloys with or without thermal barrier coatings (TBCs). The ablation mechanisms of different combinations of laser frequencies and energies are explored through a combination of simulation and experiments. A two-dimensional axisymmetric model was constructed to simulate the single - pulse ablation process. It was found that in the initial stage of laser irradiation, the energy density at the center of the laser spot was high, causing the material to rapidly heat up and vaporize. Heat diffused both longitudinally and transversely over time, expanding the heat affected zone. After the laser irradiation ceased, the surface temperature of the material dropped sharply, and heat was mainly conducted longitudinally. Under different parameter combinations, the material was mainly removed through continuous vaporization at high frequency and low energy (f = 500 kHz, E = 0.4 mJ). A mixed mechanism of central vaporization and peripheral melting occurred at medium frequency and medium energy (f = 250 kHz, E = 0.8 mJ). Heat diffusion, molten pool flow, and material redeposition were promoted at low frequency and high energy (f = 50 kHz, E = 1.6 mJ). Experiments indicated that different parameters had various effects on FCHs. Medium frequency and medium energy conditions were likely to generate cracks and melt accumulation, while low frequency and high energy conditions severely ablated the TBC structure. The material removal mechanisms mainly included vaporization, melting, shock waves, and melt injection. The dominant mechanisms differed under different parameters. The vaporization dominated at high frequency and low energy. The molten material was ejected and resolidified at the orifice at medium frequency and medium energy. The shock wave effect was significant at low frequency and high energy.