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Cinética de dissolução da superfície de aço SAE-AISI 1005 em meio ácido

Magnani, Marina; Fugivara, Cecílio Sadao; Garcia, Roberto; Benedetti, Assis Vicente
Fonte: Editora Unesp Publicador: Editora Unesp
Tipo: Artigo de Revista Científica Formato: 113-124
POR
Relevância na Pesquisa
46.33%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); O setor automotivo é um dos mais competitivos e um grande consumidor de materiais ferrosos, que exigem uma eficiente proteção contra a corrosão. Esta proteção é alcançada aplicando revestimentos adequados. Para se aplicar revestimentos se requer uma cuidadosa preparação da superfície que pode ser feita por ataque químico. Neste trabalho, determinou-se a velocidade de reação do aço extra-doce, SAE-AISI 1005, laminado a frio (CFF) utilizando várias soluções ácidas, de baixo custo, baixa agressividade ao meio ambiente e que geram pouco hidrogênio. O estudo cinético foi realizado medindo-se a perda de massa (deltam/mg cm-2) de chapas de aço CFF em função do tempo (s) de reação nas diferentes soluções, com e sem agitação, a 30ºC. Os resultados foram interpretados considerando-se os efeitos de transporte de massa, o efeito oxidante dos íons Me3+ e inibidor dos íons Fe2+. Dentre as várias soluções estudadas a que apresentou maior velocidade de reação foi a solução de H2SO4 2 M + MeCl3 1 M, v = 15,44 x 10-6 g cm-2s-1 para tempos até 1800 s.; The automotive sector is one of the biggest consumers of ferrous materials...

Electrochemical behavior of cobalt oxide coatings on cold-rolled steel in alkaline sodium sulfate

Silva, G. C.; Fugivara, C. S.; Tremiliosi, G.; Sumodjo, PTA; Benedetti, A. V.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 1875-1883
ENG
Relevância na Pesquisa
106.33%
The electrochemical behavior of a coating of cobalt oxide on cold-rolled steel in alkaline sodium sulfate was Studied using the electrochemical techniques of open-circuit potential measurements and electrochemical impedance spectroscopy. The coating was prepared at different annealing temperatures ranging from 350 to 750 degreesC and characterized by SEM, EDX and XRD. Below 550 degreesC the composition of the coating was basically of Co3O4. At 750 degreesC CoO was formed and big cracks appeared on the film exposing an inner layer of iron oxides. Analysis of the EIS data is very difficult because of the complexity of the interface structure. It can be inferred that the charge transfer resistance of the coatings prepared at 350 and 450 C were higher than those for the coatings prepared at temperatures above 550 degreesC. (C) 2002 Published by Elsevier B.V. Ltd.

A Protective packaging evaluation involving a high barrier film lamiation, desiccants and oxygen absorbers

Rollo, Philip
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.01%
The purpose of the following study was to evaluate and compare the corrosion protection capabilities of specific packaging devices / systems-high barrier film lamination, desiccant and oxygen absorber. The hypothesis of this particular study states that a film pouch constructed from a high barrier film laminated material, can offer a moderate to high degree of protection for metal surfaces exposed to a highly corrosive environment. The particular high barrier film laminated pouch (film pouch) incorporated film layers of polyester, aluminum foil and polyethylene into its structure. The particular metal surface used in the study was a commonly used metal-cold rolled steel. Each set of metal testing subjects, called populations, contained four separate packaging systems. These four systems had a common element-they all contained the film pouch. The four systems were broken down into separate testing populations-one testing population contained a metal test subject enclosed alone in the film pouch, another population contained a desiccant with the metal subject in the film pouch, another population contained an oxygen absorber with the metal subject and another population contained both a desiccant and oxygen absorber with the metal subject. The methodology used to test the hypothesis centered around a controlled humidity chamber laboratory study. This particular test used high temperatures...

Influence of gadolinium on the microstructure and mechanical properties of steel and stainless steel

Khan,Z
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2012 EN
Relevância na Pesquisa
46.27%
Iron, in the form of steel and stainless steel, is the most commonly used metal in the world. Plain steels corrode and oxidize easily, while stainless steels exhibit improved corrosion and oxidation resistance. It has been found that rare earth metal (REM) additions, such as cerium and erbium, result in the improvement of the abovementioned properties in iron-containing compounds. Gadolinium is a REM, however, there is very little information available on the influence of gadolinium on the microstructure and mechanical properties of iron-containing compounds. Thus, the purpose of this research project was to determine the influence of gadolinium additions on the microstructure and mechanical properties of mild steel and 316 stainless steel. Ten alloys were produced for the purposes of this research. Five of the alloys had a base composition of mild steel while the remaining five had base composition of 316 stainless steel. The alloys for each of the base composition contained gadolinium additions of 0.1, 0.5, 1.2, and 5 weight per cent. The as-cast and the cold-rolled alloys were analysed. The alloys responded well to the cold-rolling with the exception of the 5 weight per cent gadolinium mild steel and stainless steel alloys. These alloys were extremely brittle and underwent a significant amount of cracking during the cold rolling process. A microstructural analysis of the alloys was conducted using a light optical microscope...