Microstructural and in‐depth electrochemical characterization of Zn diffusion layers on aluminum 3xxx alloy

Lanzutti, A.; Andreatta, F.; Magnan, M.; Fedrizzi, L.

doi:10.1002/sia.6602

Cited by 6 publications

(2 citation statements)

References 26 publications

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“…The measured root mean square, RMS, was 29 nm. The Volta potential difference between intermetallics and alloy matrix was determined by SKPFM, [51][52][53][54][55][56] on the same area as topographic images in Fig. 4a.…”

Section: Resultsmentioning

confidence: 99%

Real-Time AFM and Impedance Corrosion Monitoring of Environmentally Friendly Ceria Films on AA7075

Stevanović

Lekka

Lanzutti

et al. 2020

J. Electrochem. Soc.

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Cerium-based conversion coatings have emerged as promising green alternatives to the harmful chromium-based ones, but the mechanism of corrosive protection still remains a subject of academic and industrial research. This study focuses at small scale phenomena of corrosion inhibition imparted by ceria (CeO2) to AA7075. Ceria nanoparticles were deposited from diluted and concentrated CeO2 sols by immersion. A multi-analytical approach, combining Atomic Force microscopy (AFM), Scanning Kelvin Probe Force Microscopy, Glow Discharge Optical Emission Spectroscopy, open circuit potential and electrochemical impedance spectroscopy was employed. Deposition of ceria films led to deactivation of cathodic sites, i.e. decreased Volta potential difference, resulting in increased corrosion inhibition. In situ AFM real-time monitoring revealed that during exposure to NaCl electrolyte, the changes in size of deposited ceria aggregates occurred: nanoparticles disintegrated/desorbed and re-deposited at the coating surface. The process was found to be dynamic in nature. Small particles size and inherent reactivity are believed to accelerate this phenomenon. Due to the greater CeO2 reservoir, this phenomenon was more pronounced with a thicker film, imparting longer term protection.

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Section: Resultsmentioning

confidence: 99%

Real-Time AFM and Impedance Corrosion Monitoring of Environmentally Friendly Ceria Films on AA7075

Stevanović

Lekka

Lanzutti

et al. 2020

J. Electrochem. Soc.

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“…The liquidus temperature of Al-Zn alloy is from 380 °C to 450 °C. Although it has a perfect melting temperature, its wettability is much worse than that of Al-Si alloy, and more importantly, the corrosion resistance of Al-Zn alloy is much lower than that of Al-Si alloy, which makes it difficult to be used in heat exchangers [ 17 , 18 ]. Mg can break oxide film on the surface of aluminum alloys in vacuum conditions since Mg has stronger atomic activity and higher vapor pressure than Al, making Al-Mg alloy often used as a vacuum brazing filler metal [ 19 , 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

Controlled Atmosphere Brazing of 3003 Aluminum Alloy Using Low-Melting-Point Filler Metal Fabricated by Melt-Spinning Technology

Gao

Qin

2022

Materials

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3003 aluminum alloy was widely used for the manufacturing of heat exchangers in the automotive industry by employing controlled atmosphere brazing (CAB) with NOCOLOK flux brazing technology. However, commercially available filler metals for NOCOLOK flux brazing technology are usually required to be carried out at a relatively high temperature, causing the assembled heat exchanger to be partially molten or easily deformed. A new low-melting-point brazing filler metal Al-5.0Si-20.5Cu-2.0Ni was prepared by using melt-spinning technology and then applied to CAB of 3003 aluminum alloy in this research. The solidus and liquidus of brazing filler metal was 513.21 °C and 532.48 °C. All elements were evenly distributed and free from elemental segregation. The microstructure of brazing filler metal was uniform, and the grain size was less than 500 nm. As the brazing temperature reached 575 °C, the void in the joint disappeared completely. The morphology of CuAl2 was sensitive to the brazing temperature and dwell time. The appearance of net-like CuAl2 brazed at 575 °C for 20 min was more beneficial to improve joint mechanical properties. The leakage rate of the joint was qualified to be 10−10 Pa·m3/s when the brazing temperature was 570 °C or higher. The maximum shear strength of 76.1 MPa can be obtained when the joint was brazed at 575 °C for 20 min. More dwell time induced growth of the interfacial layer and reduced joint shear strength. The open circuit potential and corrosion current density test indicated that the brazing filler metal Al-5.0Si-20.5Cu-2.0Ni had better corrosion resistance than that of 3003 aluminum alloy.

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Effects of post-printing heat treatment on microstructure, corrosion and wet wear behavior of CoCrW alloy produced by L-PBF process

et al. 2023

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CoCr alloys are widely used as human implants because of both their superior corrosion resistance and superior mechanical properties (fatigue, wear resistance, etc.) respect to other metal alloys used in biomedical field. In particular, CoCrW alloys are used mainly to produce dental implants. In this study, the effects of thermal treatment on the corrosion resistance and wet wear resistance of CoCrW alloys produced via Laser-Powder Bed Fusion (L-PBF) were investigated, and the corrosion resistance and wet wear resistance of the L-PBF specimens were compared with those of the specimens obtained after forging. The heat treatment involved the solubilization of the alloy at 1150 °C in an Ar-saturated atmosphere, followed by furnace cooling. A detailed microstructural characterization of the L-PBF specimens was carried out using a light microscope and a scanning electron microscope in both the horizontal and vertical growth directions. Scanning Kelvin probe measurements were performed on the heat-treated specimens obtained by three-dimensional printing and forging. The void contents of the specimens were evaluated using the Archimedes’ method and image analysis. Vickers (HV2) hardness measurements were performed to evaluate the mechanical properties of the specimens. The corrosion properties of the specimens were evaluated by carrying out potentiodynamic tests in two different corrosive media (aqueous solution (9 g/L NaCl) at pH = 2 and 7). The corroded areas of the specimens were then examined using scanning electron microscopy (SEM). Finally, tribological tests were performed using the pin (Ti counter material)-on-flat configuration under dry and wet conditions, using the same corrosive environments as those used in the potentiodynamic tests and two different stroke lengths. The worn samples were characterized using SEM to investigate their wear mechanisms, and a stylus profilometer was used to determine the wear rates of the materials. The experimental results showed that the additively manufactured CoCrW L-PBF alloy had higher corrosion resistance than the wrought material. In addition, the additively manufactured material showed better dry and wet wear performances than the wrought material. Nevertheless, the heat treatment did not affect the properties evaluated in this study.

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Microstructural and in‐depth electrochemical characterization of Zn diffusion layers on aluminum 3xxx alloy

Cited by 6 publications

References 26 publications

Real-Time AFM and Impedance Corrosion Monitoring of Environmentally Friendly Ceria Films on AA7075

Real-Time AFM and Impedance Corrosion Monitoring of Environmentally Friendly Ceria Films on AA7075

Controlled Atmosphere Brazing of 3003 Aluminum Alloy Using Low-Melting-Point Filler Metal Fabricated by Melt-Spinning Technology

Effects of post-printing heat treatment on microstructure, corrosion and wet wear behavior of CoCrW alloy produced by L-PBF process

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