Effects of mechanical and chemical pre-treatments on the morphology and composition of surfaces of aluminium alloys 7075-T6 and 2024-T3

Tiringer, Urša; Kovač, Janez; Milošev, Ingrid

doi:10.1016/j.corsci.2017.02.018

Cited by 75 publications

(46 citation statements)

References 40 publications

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“…5 shows the E OCP curves for 18 h of immersion in 3.5% NaCl. The E OCP values for the AA 7075-T6 alloy substrate were between −0.7 and −0.8 V vs. Ag|AgCl|KCl 3mol/L , which are typical values for aluminum alloys in chloride solutions containing oxygen [63,64], and tended to stabilize at around −0.78 V vs. Ag|AgCl|KCl 3mol/L . Small potential oscillations were observed, which could have been related to the attack of the oxide layer by chloride ions and repassivation of the surface [65].…”

Section: Open Circuit and Polarization Studiesmentioning

confidence: 82%

Corrosion behavior of WC-Co coatings deposited by cold gas spray onto AA 7075-T6

et al. 2018

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This work reports a morphological, mechanical, and corrosion resistance characterization of WC-12Co and WC-25Co coatings deposited by cold gas spray (CGS) onto AA 7075-T6 alloy. Cross-sectional images of the coatings revealed dense structures with low porosities. The coating thicknesses were 65 μm for WC-12Co and 118 μm for WC-25Co. XRD analysis showed that no fragile phases were formed in the coatings. SEM images and electrochemical results obtained after 700 h exposure to NaCl solution showed that WC-25Co exhibited better corrosion resistance performance. The WC-12Co and WC-25Co coatings withstood 1000 and 3000 h of salt fog spray test, respectively.

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Section: Open Circuit and Polarization Studiesmentioning

confidence: 82%

Corrosion behavior of WC-Co coatings deposited by cold gas spray onto AA 7075-T6

et al. 2018

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“…Following E corr , the increase in current density was not abrupt and E bd appeared at −0.66 V, giving a ∆E of 120 mV. This behavior indicates a relatively good corrosion resistance of AA3003 in chloride-containing solution compared to other, less corrosion-resistant alloys [15]. Compared to the untreated AA3003, the chemically pre-treated samples showed smaller j corr and more positive E corr ( Table 1).…”

Section: Electrochemical Measurementsmentioning

confidence: 90%

“…Coated samples show similar position of the O 1s peak but the shape of the peak became broader, indicating that was composed of several oxides, i.e., Al, Cr, and Zr. The Al 2p spectrum (Figure 15b) for pre-treated AA3003 consist of two peaks at 72.3 eV and 74.8 eV characteristic for Al metal and oxidized Al [15]. After immersion in the conversion bath for 90 s, the Al 2p peaks slightly shifted but the shape and Al content remained similar (Figure 15b).…”

Section: Locationmentioning

confidence: 98%

Protection of Aluminum Alloy 3003 in Sodium Chloride and Simulated Acid Rain Solutions by Commercial Conversion Coatings Containing Zr and Cr

et al. 2019

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The morphology, composition and corrosion properties of commercial hexafluoro-zirconate trivalent chromium coatings (SurTec® 650) deposited on chemically cleaned aluminum alloy 3003 were studied. The coatings were deposited at room temperature using different concentrations of SurTec® 650 (10, 25 and 50 vol.%) and different conversion times (90 s, 11 min and 18 min). Scanning electron microscopy with energy dispersive X-ray spectrometry, X-ray photoelectron spectroscopy and time-of-flight secondary ion spectrometry were employed to investigate the surface morphology, composition and thickness of uncoated and coated AA3003 samples. The morphology of the coating varied from uniform nodular to non-uniform and cracked; coatings were deposited at intermetallic particles and at the alloy matrix. The main constituents of conversion coatings were Zr(IV) and Cr(III) oxides; in addition to oxides, fluorides were also formed. The corrosion properties were investigated in two solutions: more aggressive sodium NaCl and less aggressive simulated acid rain. These commercial conversion coatings exhibited a good corrosion resistance but only after longer immersion in solution, i.e., 24 h. The results reveal an interesting behavior of zirconate-based coatings on aluminum-manganese alloy.

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“…La relación de las intensidades de ambos picos, I ox /I Met , se emplea para estimar el espesor de la capa pasiva de las muestras (Moffitt et al, 2001;Hughes et al, 2005;Viroulaud et al, 2017;Tiringer et al, 2017) a través de la Ec. (1), propuesta por Strohmeier (1990).…”

Section: Caracterización Superficial Mediante Xpsunclassified

Modificaciones de la microestructura y la capa pasiva de la aleación 2024-T3 Al-Cu durante una limpieza química empleada en la industria aeroespacial

et al. 2019

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Se han investigado los efectos de un pretratamiento superficial empleado en el sector aeroespacial sobre la aleación 2024-T3 Al-Cu antes de la generación de recubrimientos por conversión química. Estos pretratamientos influyen en las fases metálicas, que desempeñan un papel clave en el desarrollo de nuevos recubrimientos de conversión sin cromo y en la susceptibilidad a la corrosión localizada en medios que contienen cloruros. El pretratamiento estudiado consta de dos etapas alcalinas y una ácida. La microscopía electrónica de barrido reveló que después del proceso completo, las fases Al(Cu,Mg) se eliminaban parcial o totalmente mediante desaleación y su posterior enriquecimiento de cobre, mientras que solo se atacó la matriz de aluminio que rodeaba las fases Al(Cu,Fe,Mn,Si). El análisis electroquímico reveló el viraje a catódico de las fases Al(Cu,Mg) que aún permanecen en la superficie mientras que la fases Al(Cu,Fe,Mn,Si) presentaron un mayor potencial de corrosión que la matriz de aluminio. Por el contrario, ninguna de estas fases se vio afectada cuando se emplearon únicamente las dos etapas alcalinas. Identificados los procesos que tienen lugar cuando la aleación es sometida a un pretratamiento superficial, es posible diseñar sistemas de protección alternativos a los cromatos.

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Effects of mechanical and chemical pre-treatments on the morphology and composition of surfaces of aluminium alloys 7075-T6 and 2024-T3

Cited by 75 publications

References 40 publications

Corrosion behavior of WC-Co coatings deposited by cold gas spray onto AA 7075-T6

Corrosion behavior of WC-Co coatings deposited by cold gas spray onto AA 7075-T6

Protection of Aluminum Alloy 3003 in Sodium Chloride and Simulated Acid Rain Solutions by Commercial Conversion Coatings Containing Zr and Cr

Modificaciones de la microestructura y la capa pasiva de la aleación 2024-T3 Al-Cu durante una limpieza química empleada en la industria aeroespacial

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