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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2022, Vol. 43 ›› Issue (4): 525353.doi: 10.7527/S1000-6893.2021.25353

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Water-assisted laser scanning machining test of thermal barrier coating

WANG Bin1,2,3, WANG Haitao1,2, WANG Yufeng1,2, ZHANG Wenwu1,2   

  1. 1. Institute of Advanced Manufacturing Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China;
    2. Key Laboratory of Aero Engine Extreme Manufacturing Technology of Zhejiang Province, Ningbo 315201, China;
    3. College of Materials Science and Opto-electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2021-02-01 Revised:2021-03-02 Published:2021-07-20
  • Supported by:
    Key Deployment Projects of the Chinese Academy of Sciences (ZDRW-CN-2019-01);Excellent Projects of Zhejiang Province (2020C01036);Natural Science Foundation of Zhejiang Province (LY18E050027);Science and Technology Innovation 2025 Major Project of Ningbo City (2019B10074)

Abstract: To improve the overall performance and reliability of turbine engines, it is necessary to drill a large number of air film cooling holes on the single-crystal superalloy turbine blades with Thermal Barrier Coating (TBC). Laser processing is an advantageous method to realize coating before drilling. By using the water-assisted laser scanning machining, the orthogonal test and the single factor test have been conducted to study the effects of various factors on the TBC damage and its material removal rate. The results show that the impacts of spot overlap rate, laser repetition frequency, laser current and the pump voltage on the coating damage are in descending order. When the spot overlap rate is 98%, the laser repetition frequency 50 kHz, the laser current 38 A and the pump voltage 14 V, the peeling damage can be avoided in TBC water-assisted laser processing. While the effects of laser current, laser repetition frequency, pump voltage and spot overlap rate on TBC material removal rate are in descending order. When the optimal laser current is 38 A, laser repetition frequency 15 kHz, pump voltage 14 V and spot overlap rate 80%, the material removal efficiency of TBC is the highest. It has been analyzed that the coating peeling damage in TBC water-assisted laser processing is resulted from the joint effects of thermal stress and plasma dynamical shock. Meanwhile, the bubble cavitation caused by water-assisted laser processing will whiten the color of the coating around the processing area, with an influence range of about 59.5 μm and the removal thickness of cavitation about 2.7 μm. The research above has provided technical support for efficient and low damage laser processing of gas film holes in single-crystal superalloy turbine blades with thermal barrier coating.

Key words: thermal barrier coating, water-assisted laser scanning machining, turbine blade, film cooling hole, damage analysis, orthogonal test, process parameter optimization

CLC Number: