Electrochemical corrosion behaviour of Mg–Al alloys with thermal spray Al/SiCp composite coatings |
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Authors: | A Pardo S Feliu Jr M C Merino M Mohedano P Casajús R Arrabal |
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Affiliation: | 1. Materials Science Department, Chemistry Faculty , Universidad Complutense , 28040 , Madrid , Spain;2. Centro Nacional de Investigaciones Metalúrgicas CsiC , Avenida Gregorio del Amo 8, 28040 , Madrid , Spain |
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Abstract: | The corrosion protection of Mg–Al alloys by flame thermal spraying of Al/SiC particles (SiCp) composite coatings was evaluated by electrochemical impedance spectroscopy in 3.5 wt.% NaCl solution. The volume fraction of SiCp varied between 5 and 30%. The as-sprayed Al/SiCp composite coatings revealed a high number of microchannels, largely in the vicinity of the SiCp, that facilitated the penetration of the electrolyte and the subsequent galvanic corrosion of the magnesium substrates. The application of a cold-pressing post-treatment reduced the degree of porosity of the coatings and improved the bonding at the coating/substrate and Al/SiC interfaces. This resulted in improved corrosion resistance of the coated specimens. The effectiveness of the coatings slightly decreased with the addition of 5–30 vol.% SiCp compared with the unreinforced thermal spray aluminium coatings. |
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Keywords: | magnesium alloys composite coatings corrosion thermal spraying |
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