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(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

WC-CoCr coatings sprayed by high velocity oxygen-fuel (HVOF) flame on AA7050 aluminum alloy: electrochemical behavior in 3.5% NaCl solution

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Author(s):
Marina Magnani [1] ; Patrícia Hatsue Suegama [2] ; Abel André Cândido Recco [3] ; Josep Maria Guilemany [4] ; Cecílio Sadao Fugivara [5] ; Assis Vicente Benedetti [6]
Total Authors: 6
Affiliation:
[1] Universidade Estadual Paulista. Instituto de Química - Brasil
[2] Universidade Estadual Paulista. Instituto de Química - Brasil
[3] Universidade de São Paulo. Escola Politécnica - Brasil
[4] Universitat de Barcelona. Materials Engineering. CPT Thermal Spray Centre - Espanha
[5] Universidade Estadual Paulista. Instituto de Química - Brasil
[6] Universidade Estadual Paulista. Instituto de Química - Brasil
Total Affiliations: 6
Document type: Journal article
Source: MATERIALS RESEARCH-IBERO-AMERICAN JOURNAL OF MATERIALS; v. 10, n. 4, p. 377-385, 2007-12-00.
Abstract

In the present work, the electrochemical behavior of WC-CoCr coatings with 10 (W10), 15 (W15) and 20 (W20) torch passes sprayed by High Velocity Oxygen-Fuel (HVOF) flame on AA7050 aluminum alloy substrate, evaluated in 3.5% NaCl solution, were compared using open-circuit potential (E OC) measurements, electrochemical impedance spectroscopy (EIS) and polarization curves. The coating surfaces and their cross sections were characterized by X ray diffraction and the Rockwell-C hardness test, and also by optical (OM) and scanning electron microscopy (SEM) before and after the corrosion tests. The electrochemical data showed that sample W10 presented higher corrosion resistance than the others in chloride solutions. In some tests, aluminum salts on the coating surface were identified by EDS, indicating the corrosion of the substrate. And using aluminon, aluminum ions were detected and analyzing the surface via stereomicroscopy, hydrogen bubbles were observed, both showing that the electrolyte reached the substrate and galvanic corrosion possibly occurred. The physical characterization showed that sample W10 presented a lower number of cracks and pores, justifying its higher corrosion resistance. (AU)