Hot corrosion behavior of electrodeposited SiO2 coating on TiAl alloy. (September 2020)

• Record Type: Journal Article
• Authors: Wu, Lian-Kui; Wu, Jing-Jia; Wu, Wei-Yao; Yan, Hao-Jie; Jiang, Mei-Yan; Cao, Fa-He
• Is Part Of: Corrosion science. Volume 174(2020)
• Publication Date: 2020-09
• Subjects: Hot corrosion -- TiAl alloy -- Coating -- SiO2; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2020.108827
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: Electrodeposited SiO2 coating can efficiently improve the hot corrosion resistance of TiAl alloy. Compact and adherent corrosion scale generates during the hot corrosion process. The dissolution of SiO2 into the molten sodium salt leads to the generation of Na2 Si4 O9 . The compact Al2 O3 layer at the coating/alloy interface benefits to improve the hot corrosion resistance. Abstract: To improve the hot corrosion resistance, thickness controllable SiO2 coating was electrodeposited on TiAl alloy. The hot corrosion behavior of the specimens contaminated with 75 wt.% Na2 SO4 + 25 wt.% NaCl salt mixture was investigated at 700 °C. Results showed that the generation of compact amorphous SiO2 embedded with Na2 Si4 O9 and cristobalite was responsible for the enhanced hot corrosion resistance. Moreover, the SiO2 coating does not only act as a diffusion barrier to sulfur and chlorine but also decreases the oxygen partial pressure at the coating/alloy interface, therefore promoting the selective oxidation of Al to form protective Al2 O3 layer.