Flow microcapillary plasma mass spectrometry-based investigation of new Al-Cr-Fe complex metallic alloy passivation.
Al-Cr-Fe complex metallic alloys are new intermetallic phases with low surface energy, low friction, and high corrosion resistance down to very low pH values (0-2). Flow microcapillary plasma mass spectrometry under potentiostatic control was used to characterize the dynamic aspect of passivation of an Al-Cr-Fe gamma phase in acidic electrolytes, allowing a better insight on the parameters inducing chemical stability at the oxyhydroxide-solution interface. In sulfuric acid pH 0, low element dissolution rates (in the µg cm(-2) range after 60 min) evidenced the passive state of the Al-Cr-Fe gamma phase with a preferential over-stoichiometric dissolution of Al and Fe cations. Longer air-aging was found to be beneficial for stabilizing the passive film. In chloride-containing electrolytes, ten times higher Al dissolution rates were detected at open-circuit potential (OCP), indicating that the spontaneously formed passive film becomes unstable. However, electrochemical polarization at low passive potentials induces electrical field generated oxide film modification, increasing chemical stability at the oxyhydroxide-solution interface. In the high potential passive region, localized attack is initiated with subsequent active metal dissolution.
Laboratory for Analytical Chemistry, EMPA - Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland; EPFL - École Polytechnique Fédérale de Lausanne, ENAC-IIE, 1015 Lausanne, Switzerland. Electronic address: noem.ott@gmail.com.
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Ott
Laboratory for Joining Technologies and Corrosion, EMPA - Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
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Beni
Laboratory for Analytical Chemistry, EMPA - Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
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Ulrich
EPFL - École Polytechnique Fédérale de Lausanne, ENAC-IIE, 1015 Lausanne, Switzerland; PSI - Paul Scherrer Institute, ENE-LBK, 5232 Villigen PSI, Switzerland.
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Ludwig
Laboratory for Joining Technologies and Corrosion, EMPA - Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland. Electronic address: patrik.schmutz@empa.ch.
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Schmutz
D000497:Alloys / Q000737:chemistry*; D000535:Aluminum / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D003343:Corrosion; D004573:Electrolytes / Q000737:chemistry; D004867:Equipment Design; D007501:Iron / Q000737:chemistry*; D013058:Mass Spectrometry / Q000295:instrumentation*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation; D013499:Surface Properties
D000497:Alloys; D004573:Electrolytes; D002857:Chromium; D000535:Aluminum; D007501:Iron
Al–Cr–Fe complex metallic alloys; Flow cell; ICPMS analysis; Microcapillary; Passivity; Potentiostatic polarization