13 documents found, page 1 of 2
Redução electroquímica de iões de terras raras e o seu efeito na corrosão de me...
Oliveira, Marco; Bastos, A.C.; Kallip, Silvar; Zheludkevich, Mikhail; Ferreira, M.G.S.RESUMO: Os iões de terras raras estão entre os inibidores de corrosão de nova geração mais promissores. No entanto, foram encontradas condições onde a corrosão é acelerada na presença destes iões [1]. O caso mais relevante devido à sua importância é o aumento da corrosão do zinco no par galvânico zinco-ferro. Esse aumento está associado a uma reacção catódica adicional inesperada que é observada nas curvas de p...
Smart coating for detection of early-stage corrosion of steel
Sushkova, Alesia; Wilhelm, Manon; Montes, Rodrigo; Neves, Cristina; Quevedo-Reyes, Marcela; Bastos, A.C.; Ferreira, M.G.S.; Tedim, JoãoABSTRACT: The work describes the investigation of LDH-based nanoadditives for early-stage corrosion detection of steel, and subsequent development of a multi-layer functional protection coating. A systematic study on the level of degradation and the detected colorimetric signal was performed using electrochemical characterisation. The protection properties and detection functionality were also studied in condit...
Um roteiro para a produção de metal duro com maior resistência à corrosão
Ferro Rocha, Alexandre; Senos, A.M.R.; Bastos, A.C.; Ferreira, M.G.S.RESUMO: Com o objetivo de racionalizar o desenvolvimento de compósitos de metal duro com maior resistência à corrosão, realizou-se um estudo sistemático da influência de vários parâmetros que determinam o seu desempenho. Neste trabalho apresentam-se resultados da influência de parâmetros relacionados com a constituição do material (tipo de ligante e tamanho de grão de carboneto de tungsténio - WC) e de parâmetr...
Insights into corrosion behaviour of uncoated Mg alloys for biomedical applicat...
Neves, C.S.; Sousa, I.; Freitas, M.A.; Moreira, L.; Costa, C.; Teixeira, J.P.; Fraga, S.; Pinto, E.; Almeida, A.; Scharnagl, N.; Zheludkevich, M.L.MgCa and MgGd series of alloys are often reported as promising candidates for biomedical applications. In the present study, cytotoxicity and corrosion behavior of Mg1Ca and Mg10Gd alloys in different electrolytes (NaCl, PBS, MEM) have been investigated in order to make a direct comparison and understand the mechanisms behind their performance. Potentiodynamic polarization and electrochemical impedance spectros...
A critical look at interpretation of electrochemical impedance spectra of sol-g...
Yasakau, K. A.; Starykevich, M.; Ferreira, M.G.S.; Zheludkevich, M.L.A proper assignment of time constants is important for the correct interpretation of the electrochemical impedance spectra of coated substrates. In this work, several model aluminium samples with different anodic oxide thicknesses were prepared and characterised. The aluminium samples were coated by a hybrid sol-gel formulation and studied by electrochemical impedance spectroscopy (EIS) during immersion in NaCl...
Microstructural characterization and corrosion resistance of WC-Ni-Cr-Mo compos...
Santos, R.F.; Rocha, A.M. Ferro; Bastos, A.C.; Cardoso, J.P.; Rodrigues, F.; Fernandes, C.M.; Sacramento, J.; Ferreira, M.G.S.; Senos, A.M.R.WC-Ni-Cr-Mo are good candidates for replacing WC-Co for its better corrosion performance. This work investigated the effect of different Mo content on the mechanical properties and corrosion susceptibility of WC-Ni-Cr-Mo composites in chloride and sulphate acidic media. Chemical, microstructural, and electrochemical analysis were performed. Results show chlorides are frankly more aggressive than sulphates, but ...
Cast iron corrosion protection with chemically modified Mg Al layered double hy...
Vieira, D.E.L.; Sokol, D.; Smalenskaite, A.; Kareiva, A.; Ferreira, M.G.S.; Vieira, J. M.; Salak, A. N.Layered double hydroxides (LDHs) intercalated with corrosion inhibitive species are considered as promising additives to protection coatings. However, the conventional method of LDH preparation via co-precipitation followed by anion exchange is a water consuming and slow process hardly applicable to industrial use. In this work, a novel approach to LDH synthesis via hydration of sol-gel prepared mixed metal oxi...
Corrosion behaviour of WC hardmetals with nickel - based binders
Rocha, A.M. Ferro; Bastos, A.C.; Cardoso, J.P.; Rodrigues, F.; Fernandes, C.M.; Soares, E.; Sacramento, J.; Senos, A.M.R.; Ferreira, M.G.S.Cobalt is the standard binder in tungsten carbide (WC) hardmetals due to its compatibility with the WC phase, resulting in composites with exceptional hardness and wear resistance. However, their corrosion resistance is not satisfactory in many applications, leading to the early deterioration and failure of tools and equipment. In this work, the corrosion of WC hardmetals with three alternative binders (FeCoNi,...
Layered double hydroxide based active corrosion protective sealing of plasma el...
Bouali, A.C.; Straumal, E.A.; Serdechnova, M.; Wieland, D.C.F.; Starykevich, M.; Blawert, C.; Hammel, J.U.; Lermontov, S.A.; Ferreira, M.G.S.This work reports a novel approach for growing layered double hydroxide (LDH) films on any plasma electrolytic oxidation (PEO) coated AA2024 independently of the nature of the PEO coating. The specific PEO coating chosen to carry out this work is considered to be not suitable for direct LDH growth because of phase composition and morphological features. In this paper, we describe a new methodology that consists...
Nanostructured corrosion sensing coatings for aeronautical applications
Galvão, T.L.P.; Sousa, I.; Wilhelm, M.; Opršal, J.; Kukačková, H.; Špaček, V.; Scharnagl, N.; Maia, F.; Gomes, J.R.B.; Ferreira, M.G.S.; Tedim, J.It is critical for the aeronautical industry that the next generation of smart coatings allows the early detection and continuous monitoring of corrosion. Once corrosion is detected, preventive actions can be taken in order to mitigate its costs. Our strategy relies on functional coatings capable of detecting metallic corrosion early on. After appropriate selection of sensing compounds and subsequent loading in...