Effect of Yttrium Ion on YSZ-Al₂O₃ Composite Coating Formed by PEO on a Cast Al-Si-Cu-Ni Alloy

Abstract:

Y₂O₃-ZrO₂-Al₂O₃ (YSZ-Al₂O₃) composite ceramic coating was formed on a cast Al‑12Si-3Cu-2Ni alloy by plus AC plasma electrolytic oxidation (PEO) process, with yttrium ion concentrations varying from 0 to 0.5 g/l and process time from 0 to 45 min. The microstructures of the coatings were investigated by SEM and XRD. The results show that the PEO coating growth behaviour and microstructure were affected greatly by Y ion additions. At a given oxidation time, the coating growth rate accelerated and thickness increased in the PEO process when adding yttrium ions. When the content of Y ions is greater than the optimum value of 0.05 g/l, coating growth gradually decreases. In comparison with a ZrO₂-Al₂O₃ coating, the amount of micro particle in YSZ-Al₂O₃ coating is less and the ceramic layer is repeatedly deposited by ceramic particles and good binding was achieved between the ceramic coating and the base alloy. The uniform and compact YSZ-Al₂O₃ composite coating is mainly composed of c-Y_0.15Zr_0.85O_1.93 solid solution, m‑ZrO₂, α-Al₂O₃, γ-Al₂O₃ and Y₂O₃ phases. The ZrO₂ phase was well stabilized by solid solution containing yttrium element and Al₂O₃.

• Periodical: Materials Science Forum (Volume 765)
• Pages: 668-672
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.765.668
• Online since: July 2013
• Authors: Ping Wang, Dao Xin Liu, Jian Ping Li, Yong Chun Guo, Zhong Yang
• Keywords: Al-Si-Cu-Ni Aluminium Alloy, Composite Ceramic Coating, Plasma Electrolytic Oxidation, YSZ-Al₂O₃, Yttrium Ion, ZrO₂-A₂O₃

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