Journal of Inorganic Materials ›› 2013, Vol. 28 ›› Issue (12): 1369-1375.doi: 10.3724/SP.J.1077.2013.13091

• Research Paper • Previous Articles     Next Articles

Microstructure and High Temperature Oxidation Resistance of Si-Al-Y Co-deposition Coatings Prepared on TiAl alloy by Pack Cementation Process

LI Yong-Quan1, XIE Fa-Qin1, WU Xiang-Qing1, LI Xuan1,2   

  1. (1. School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China; 2. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China)
  • Received:2013-02-21 Revised:2013-03-18 Online:2013-12-20 Published:2013-11-15
  • Contact: XIE Fa-Qin.
  • About author:LI Yong-Quan.
  • Supported by:

    Science and Technology Program for Research and Development of Shanxi Province(2011K07-01)

Abstract: In order to improve the oxidation resistance of TiAl alloy, Al and Y modified silicide coating were prepared by pack cementation process at 1050℃ for 0-4 h. The formative mechanism and oxidation behavior of the coating were studied. The results show that the coating prepared by co-depositing Si-Al-Y at 1050℃ for 4 h has a multiple layer structure: an outer layer composed of TiSi2, a middle layer composed of (Ti,X)5Si4 and (Ti,X)5Si3 (X represents Nb and Cr elements), an inner layer composed of TiAl2, γ-TiAl phases and a Al-rich inter-diffusion zone. Y mainly existed in the outer layer and middle layer of the coating. The coating formation process followed a sequent deposition mechanism, with Al deposited at the initial stage and Si deposited at the later stage. After oxidation at 1000℃ for 20 h, a dense scale composed of a thin TiO2 outer layer and a thick SiO2·Al2O3 inner layer is formed on the co-deposition coating. During the oxidation process, the excessive Y2O3 particles form in the interface of the scale and the substrate, which might promote the adherence of the scale effectively.

Key words: TiAl alloy, Si-Al-Y co-deposition, structural formation, equilibrium partial pressure, high temperature oxidation resistance

CLC Number: 

  • TQ174