Promoted Anodizing Reaction and Enhanced Coating Performance of Al–11Si Alloy: The Role of an Equal-Channel-Angular-Pressed Substrate

Zhou, Zhikai; Song, Dandan; Liang, Ningning; Jiang, Haiyang; Gao, Bo; Wu, Yuna; Ma, Aibin; Qiao, Yanxin; Sun, Jiapeng; Jiang, Jinghua; Ma, Xiaolong

doi:10.3390/ma12193255

Cited by 8 publications

(2 citation statements)

References 58 publications

(64 reference statements)

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“…Figure 5 illustrates the EIS Bode plots (Figure 5a) and Nyquist plots ( Figure 5b) after immersion in 3.5 wt.% NaCl solution for 1 h. Coated samples showed three time constants in the Bode plots, including two capacitive peaks in the high/middle frequencies and one capacitive peak in the low frequency. Double peaks (as marked by the two blue arrows in Figure 5a) are the typical EIS characteristics for coated samples, of which one peak relates to the single response from the coating/substrate interface and one peak relates to the response from the coating [42,43]. In this study, a third capacitive peak was also found, which may relate to the single response from the outer porous layer of the anodizing coating.…”

Section: Microstructure Characteristicssupporting

confidence: 53%

Effect of Ultrafine Grains on the Coating Reaction and Anticorrosion Performance of Anodized Pure Aluminum

et al. 2020

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This work analyzes the effects of ultrafine aluminum (Al) grains on the anodizing coating reaction and anticorrosion performance of anodized industrial pure Al. Equal-channel angular pressing (ECAP) was applied to cast pure Al continuously for 16 passes at room temperature, and its average grain size was dramatically refined to about 1.5 μm. The ultrafine-grain (UFG) pure Al was further anodized with a cast sample via a parallel anodizing circuit at a constant total input current. Benefited by the higher volume fraction of grain boundaries and higher internal energy of the UFG substrate, the anodizing process of the ECAP-processed pure Al was significantly accelerated, showing a more intense initial anodizing reaction, a faster initial coating thickening, and much earlier porous-layer formation compared to the cast sample. As the anodizing reaction continued, the newly formed thicker coating of the ECAP-coated sample significantly hindered the diffusion process, weakening the thermodynamic advantage and decreasing the anodizing current of the ECAP-processed sample. During the entire anodizing duration, the ECAP-processed pure Al experienced gradually decreased anodizing current, while the cast sample experienced increased anodizing current. Because of the more total reaction, the ECAP-coated sample always maintained a relatively thicker coating and better anticorrosion performance during the entire anodizing duration.

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