Corrosion characteristics of hybrid Al/SiC_p/MgAl₂O₄ composites fabricated with fly ash and recycled aluminum

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• 作者：R. Escalera-Lozano ; C.A. Gutié ; rrez ; M.A. Pech-Canul ; M.I. Pech-Canul
• 关键词：Al/SiC_p composites ; Corrosion ; Recycling aluminum ; Fly ash ; Galvanic couple
• 刊名：Materials Characterization
• 出版年：2007
• 期刊代码：57_10445803
• 类别：ms
• 出版时间：October 2007
• 卷：58
• 期：10
• 页码：953-960
• 文件大小：971 K

摘要

The corrosion characteristics of Al/SiC_p/spinel composites fabricated with SiC_p, fly ash (FA) and recycled aluminum were experimentally assessed. For type A composites prepared with the alloy Al–8Si–15Mg (wt.%), the Mg₂Si intermetallic precipitated during solidification acted as a microanode coupled to the matrix (in the presence of condensed humidity) and led to catastrophic localized corrosion. Although the potential attack of SiC by liquid aluminum was successfully avoided by the presence of SiO₂ in the FA, Al₄C₃ was still formed due to the reaction of carbon in the FA with aluminum. For type B composites, processed with the alloy Al–3Si–15Mg (wt.%) and calcinated FA, the silicon content was low enough to avoid formation of Mg₂Si. Moreover, chemical degradation by Al₄C₃ hydrolysis did not happen either because of the absence of carbon and the presence of SiO₂. This explains the physical integrity of type B composites even after 11 months of exposure to humid environment.