Corrosion Protection of Light Alloys Using Low Pressure Cold Spray
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JTTEE5 21:304–313 DOI: 10.1007/s11666-011-9729-7 1059-9630/$19.00 ASM International
Corrosion Protection of Light Alloys Using Low Pressure Cold Spray D. Dzhurinskiy, E. Maeva, Ev. Leshchinsky, and R.Gr. Maev (Submitted July 19, 2011; in revised form December 1, 2011) Corrosion attack of aluminum- and magnesium-based alloys is a major issue worldwide. This study provides a report on the electrochemical behavior of several types of protective metal coatings obtained by low pressure cold spray (LPCS) and describes the performance of the latters corrosion resistance properties. In this manner several metal feedstock compositions were cold sprayed on AA2024-T3 Alclad substrate. Electrochemical methods, such as open circuit potential and potentiodynamic polarization, were used in combination with materials characterization techniques to assess the performance of LPCS protective coating layers. All sprayed samples were tested in the accelerated corrosion salt spray chamber for a time period of up to 500 h to obtain corrosion kinetics data, and with specific attention being focused on the characterization of the coatings microstructural and mechanical properties. The overall conclusion of this study is that the LPCS process could be utilized to deposit corrosion protection coatings of light alloys as well as to repair aluminum and aluminum cladding structures during overhaul maintenance schedule in industry.
Keywords
AA2024, aluminum, coating, corrosion, corrosion protection, low pressure cold spray
1. Introduction High-strength aluminum alloys such as AA2024 and AA7075 are widely used in aircraft manufacture as well as in many other industries as structural components due to their high-strength/weight ratio (Ref 1, 2). Nevertheless, those alloys can be affected by different forms of corrosion such as pitting and galvanic corrosion, intergranular corrosion, stress corrosion cracking or exfoliation corrosion (Ref 1–6). It is well known that in chloride ion containing solution Al-Zn-Mg-Cu alloys are susceptible to severe localized corrosion, such as exfoliation corrosion, intergranular or crevice corrosion, and most severely, pitting (Ref 7). Localized corrosion usually sets in at heterogeneities in the microstructure of the alloy, such as coarse intermetallic phases, constituent particles, inclusions, dispersoids, or even precipitates or segregations at grain boundaries. Among these, coarse intermetallic phases always attracted attention as they are the most prominent initiation sites in alloys due to galvanic coupling effects. It is well known that Cu, Fe and Ti containing intermetallic phases are cathodic with respect to the matrix and thus promote the dissolution of the surrounding matrix (Ref 8). The Mg, Zn, or Si rich intermetallics are usually anodic D. Dzhurinskiy and R.Gr. Maev, Institute for Diagnostic Imaging Research, University of Windsor, Windsor, ON, Canada; and E. Maeva and Ev. Leshchinsky, Department of Physics, University of Windsor, Windsor, ON, Canada. Contact e-mail: [email protected].
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