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Environmental barrier coatings (EBCs) effectively protect the ceramic matrix composites (CMCs) from harsh engine environments, especially steam and molten salts. However, open pores inevitably formed during the deposition process provide the transport channels for oxidants and corrosives, and lead to premature failure of EBCs. This research work proposed a method of pressure infiltration densification which blocked these open pores in the coatings. These results showed that it was difficult for aluminum to infiltrate spontaneously, but with the increase of external gas pressure and internal vacuum simultaneously, the molten aluminum obviously moved forward, and finally stopped infiltrating at a depth of a specific geometry. Based on the wrinkled zigzag pore model, a mathematical relationship between the critical pressure with the infiltration depth and the pore intrinsic geometry was established. The infiltration results confirmed this relationship, indicating that for a given coating, a dense thick film can be obtained by adjusting the internal and external gas pressures to drive a melt infiltration.


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Pressure infiltration of molten aluminum for densification of environmental barrier coatings

Show Author's information Lin DONG1Mei-Jun LIU1( )Xiao-Feng ZHANG2( )Xue-Shi ZHUO2Jia-Feng FAN2Guan-Jun YANG1Ke-Song ZHOU2
State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China
National Engineering Laboratory for Modern Materials Surface Engineering Technology, Institute of New Materials, Guangdong Academy of Science, Guangzhou 510650, China

Abstract

Environmental barrier coatings (EBCs) effectively protect the ceramic matrix composites (CMCs) from harsh engine environments, especially steam and molten salts. However, open pores inevitably formed during the deposition process provide the transport channels for oxidants and corrosives, and lead to premature failure of EBCs. This research work proposed a method of pressure infiltration densification which blocked these open pores in the coatings. These results showed that it was difficult for aluminum to infiltrate spontaneously, but with the increase of external gas pressure and internal vacuum simultaneously, the molten aluminum obviously moved forward, and finally stopped infiltrating at a depth of a specific geometry. Based on the wrinkled zigzag pore model, a mathematical relationship between the critical pressure with the infiltration depth and the pore intrinsic geometry was established. The infiltration results confirmed this relationship, indicating that for a given coating, a dense thick film can be obtained by adjusting the internal and external gas pressures to drive a melt infiltration.

Keywords:

infiltration process, channel pore, densification, pressure assistant, environmental barrier coating (EBC)
Received: 06 April 2021 Revised: 22 July 2021 Accepted: 03 August 2021 Published: 10 November 2021 Issue date: January 2022
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Publication history
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Publication history

Received: 06 April 2021
Revised: 22 July 2021
Accepted: 03 August 2021
Published: 10 November 2021
Issue date: January 2022

Copyright

© The Author(s) 2021.

Acknowledgements

This research project was supported by the National Natural Science Foundation of China (No. 51901175), the Guangdong Province Outstanding Youth Foundation (No. 2021B1515020038), the Guangzhou Technical Research Program (No. 201906010015), the Industry University Research Project funded by Aero Engine Corporation of China (No. HFZL2019CXY015), the Postdoctoral Research Foundation of China (Nos. 2020T130499 and 2019M653602), and the National Program for Support of Top-notch Young Professionals.

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