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Corrosion characteristics of Al‐Si‐Mg/SiC p composites with varying Si/Mg molar ratio in neutral chloride solutions
Author(s) -
EscaleraLozano R.,
PechCanul M. A.,
PechCanul M. I.,
Quintana P.
Publication year - 2009
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.200805164
Subject(s) - materials science , molar , corrosion , molar concentration , composite material , molar ratio , chloride , dissolution , porosity , nuclear chemistry , metallurgy , catalysis , chemistry , medicine , biochemistry , dentistry , organic chemistry
The corrosion resistance of Al‐Mg‐Si/SiC p composites produced by the pressureless infiltration method [using SiC p preforms with 50% porosity containing rice hull ash (RHA) and four custom‐made alloys with varying Si/Mg molar ratio] was evaluated in neutral 0.1 M NaCl solutions. The deleterious phase Al 4 C 3 was successfully suppressed in composites with Si/Mg molar ratios of 0.89 and 1.05, but not in those with lower Si/Mg molar ratios (0.12 and 0.49). Results of cyclic polarizations in deareated 0.1 M NaCl solutions showed that with increasing Si/Mg molar ratio, passive current density increased but pitting susceptibility decreased both for reinforced and unreinforced alloys. Immersion tests in aerated 0.1 M NaCl showed that for composites with Si/Mg molar ratios of 0.12 and 0.49 chemical degradation by hydrolysis of Al 4 C 3 was followed by intense anodic dissolution at the matrix–reinforcement interface, while composites corresponding to Si/Mg molar ratios of 0.89 and 1.05 did not exhibit intense localized attack. Possible reasons for the improvement in resistance to localized corrosion are discussed.