An Nb2O5-SiO2-Al2O3/NbSi2/Nb5Si3 multilayer coating on Nb-Hf alloy to improve oxidation resistance

作者：Ge, Yulin; Wang, Yaming^*; Chen, Junchen; Zou, Yongchun; Guo, Lixin; Ouyang, Jiahu; Jia, Dechang; Zhou, Yu

来源：Journal of Alloys and Compounds, 2018, 745: 271-281.

DOI：10.1016/j.jallcom.2018.02.107

• Nb alloy
• Multilayer coating
• Pack cementation
• Microarc oxidation
• High temperature oxidation resistance

An Nb2O5-SiO2-Al2O3/NbSi2/Nb5Si3 multilayer coating is fabricated by a two-step method of pack cementation and microarc oxidation. The isothermal oxidation resistances of Nb2O5-SiO2-Al2O3/NbSi2/Nb5Si3 multilayer coated and NbSi2/Nb5Si3 coated Nb alloy are investigated at 1250 degrees C. The results show that the oxidation kinetics of NbSi2/Nb5Si3 coated Nb alloy follows a parabolic-like law with the parabolic rate constant k(p) of 0.79 mg(2) cm(-4) h(-1). Whereas the multilayer coated Nb alloy exhibits better oxidation resistance with a lower k(p) of 0.06 mg(2) cm(-4) h(-1) for the first 15 h oxidation period, and a comparable oxidation resistance to that of NbSi2/Nb5Si3 coated Nb alloy in the following oxidation period. The multilayer coating has successfully retarded the oxidation process, which is attributed to the formation of Al2O3 and glassy SiO2 within the Nb2O5-SiO2-Al2O3 outer layer.

• 出版日期2018-5-15
• 单位哈尔滨工业大学