Influence du pH sur les proprietes chimiques et structurales des films d'oxyde formes sur l'acier 316L et les alliages 600 et 690 dans les milieux aqueux a haute temperature |
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| Institution: | 1. Electricité de France, Service Contrôle des Matériaux Irradiés, BP 23, 37420 Avoine, France.;2. CNRS — CECM, 15 rue Georges Urbain, 94407 Vitry-sur-Seine, France.;3. Departamento da Quimica, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal;1. Department of Plant Physiology, Institute of Biology and Biochemistry, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland;2. Department of Agricultural and Environmental Chemistry, University of Life Sciences, Akademicka 15, 20-950 Lublin, Poland;1. Service de chirurgie orthopédique, traumatologique, chirurgie plastique, reconstructrice et assistance main, CHRU Jean-Minjoz, 3, boulevard Alexandre-Fleming, 25030 Besançon cedex, France;2. Unité de méthodologie et de qualité de vie en cancérologie (EA 3181) et plateforme de recherche clinique en cancérologie et qualité de vie, CHRU de Besançon, 2, place Saint-Jacques, 25000 Besançon, France;1. Laboratório de Produtos e Tecnologia em Processos (LPT), Departamento de Química Orgânica e Inorgânica, Universidade Federal do Ceará, Campus do Pici, Bloco 940, Cx. Postal 6021, 60440-900 Fortaleza, Ceará, Brazil;2. Núcleo de Pesquisas em Lubrificantes, Grupo de Pesquisa em Separações por Adsorção, Depto. De Engenharia Química, Universidade Federal do Ceará, Campus do Pici, 60455-900 Fortaleza, Ceará, Brazil;3. Laboratório de Eletroquímica e Corrosão, Departamento de Química Analítica e Físico-Química, Universidade Federal do Ceará, Bloco 939 Campus do Pici, 60455-970 Fortaleza, Ceará, Brazil;4. Departamento de Química, Instituto Federal de Educação, Ciência e Tecnologia do Maranhão, Campus São Luís Monte Castelo, São Luís, Maranhão, Brazil |
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| Abstract: | Influence of pH on the chemical and structural properties of the oxide films formed on 316L stainless steel, alloy 600 and alloy 690 in high temperature aqueous environments. The oxide films formed on 316L stainless steel, alloy 600 and alloy 690 at 320°C in high temperature aqueous environments of different pH have been examined by glow discharge optical spectroscopy, scanning electron microscopy, atomic force microscopy and capacitance measurements. The analytical study reveals that the films formed at pH 5 are mainly composed of chromium oxides. When the pH increases the chromium concentration decreases and those of the other two elements (Ni and Fe) tend to increase. The films formed at pH 5 on 316L stainless steel and alloy 600 are thick and powder-like. The film formed at the same pH on alloy 690 is thin and is composed of a compact protective inner layer and a less-compact outer layer formed by crystals of mixed iron-nickel-chromium oxides. The morphological appearance of the thick films and that of the thin films is very different. However, equivalent morphologies can be observed for the relatively thin duplex films formed at pH8 and pH9.5 on the 316L stainless steel and nickel-base alloys. The evolution of the chemical composition of the films is accompanied by important changes from the point of view of their semiconductivity. |
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