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Detalles de la revista
Formato
Revista
eISSN
1804-1213
Publicado por primera vez
03 Apr 2012
Periodo de publicación
4 veces al año
Idiomas
Inglés

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Volumen 60 (2016): Edición 1 (March 2016)

Detalles de la revista
Formato
Revista
eISSN
1804-1213
Publicado por primera vez
03 Apr 2012
Periodo de publicación
4 veces al año
Idiomas
Inglés

Buscar

5 Artículos
Acceso abierto

Study of diffusion processes in the oxide layer of zirconium alloys

Publicado en línea: 19 Mar 2016
Páginas: 1 - 5

Resumen

Abstract

In the active zone of a nuclear reactor where zirconium alloys are used as a coating material, this material is subject to various harmful impacts. During water decomposition reactions, hydrogen and oxygen are evolved that may diffuse through the oxidic layer either through zirconium dioxide (ZrO2) crystals or along ZrO2 grains. The diffusion mechanism can be studied using the Ion Beam Analysis (IBA) method where nuclear reaction 18O(p,α)15N is used. A tube made of zirconium alloy E110 (with 1 wt. % of Nb) was used for making samples that were pre-exposed in UJP PRAHA a.s. and subsequently exposed to isotopically cleansed environment of H218O medium in an autoclave. The samples were analysed with gravimetric methods and IBA methods performed at the electrostatic particle accelerator Tandetron 4130 MC in the Nucler Physics Institute of the CAS, Řež. With IBA methods, the overall thicknesses of corrosion layers on the samples, element composition of the alloy and distribution of oxygen isotope 18O in the corrosion layer and its penetration in the alloy were identified. The retrieved data shows at the oxygen diffusion along ZrO2 grains because there are two peaks of 18O isotope concentrations in the corrosion layer. These peaks occur at the environment-oxide and oxide-metal interface. The element analysis identified the presence of undesirable hafnium.

Acceso abierto

Electrochemical deposition of coatings of highly entropic alloys from non-aqueous solutions

Publicado en línea: 19 Mar 2016
Páginas: 6 - 12

Resumen

Abstract

The paper deals with electrochemical deposition of coatings of highly entropic alloys. These relatively new materials have been recently intensively studied. The paper describes the first results of electrochemical coating with highly entropic alloys by deposition from non-aqueous solutions. An electrochemical device was designed and coatings were deposited. The coatings were characterised with electronic microscopy scanning, atomic absorption spectrometry and X-ray diffraction methods and the combination of methods of thermic analysis of differential scanning calorimetry and thermogravimetry.

Acceso abierto

The influence of total reinforcement anchorage length on misinterpretation of the impact of hot-dip galvanised steel corrosion on its bond strength with concrete

Publicado en línea: 19 Mar 2016
Páginas: 13 - 20

Resumen

Abstract

To begin with, the intorduction of this paper summarises literature sources that wrongly interpret results of the bond strength between hot-dip galvanised reinforcements and concrete. The influence of the total reinforcement anchorage length on the bond strength results assessment was studied in detail. The numeric analysis of beam models with various testing anchorage lengths (the analysis input data comprised the results of previous bond strength tests carried out in a laboratory) unambiguously confirmed that when the bond strength between concrete and hot-dip galvanised reinforcement with a sufficient test anchorage length is tested in a beam test, the negative impact of the coating corrosion on bond strength with concrete may be biased. It is more objective to test bond strength with concrete in a pull-out test where a very short test reinforcement anchorage length is set out as a standard.

Acceso abierto

Operation corrosion test of austenitic steel bends for supercritical coal boilers

Publicado en línea: 19 Mar 2016
Páginas: 21 - 27

Resumen

Abstract

Corrosion tests of both annealed and not annealed bends of HR3C and S304H steels in operation conditions of black and brown coal combustion boilers in EPRU and EDE. After a long-term exposure, the samples were assessed gravimetrically and metallographically. The comparison of annealed and unannealed states showed higher corrosion rates in the annealed state; corrosion of the sample surface did not essentially differ for compression and tensile parts of the beams. Detailed assessment of both steels is described in detail in this study.

Acceso abierto

Protection of historical lead against acetic acid vapour

Publicado en línea: 19 Mar 2016
Páginas: 28 - 34

Resumen

Abstract

Historical lead artefacts (small figurines, appliques, bull (metal seal) can be stored in depository and archives in inconvenient storage conditions. The wooden show-case or paper packagings release volatile organic compound to the air during their degradation. These acids, mainly acetic acid are very corrosive for lead. The thin layer of corrosion products which slows atmospheric corrosion is formed on lead surface in atmospheric condition. In presence of acetic acid vapour the voluminous corrosion products are formed and fall off the surface. These corrosion products do not have any protection ability. The lead could be protected against acid environment by layer of “metal soup” which is formed on surface after immersion in solution of salt of carboxylic acid for 24 hours. The solutions of acids (with vary long of carbon chain) and their salts are examined. Longer carbon chain provides better efficiency convers layer. The disadvantages are low solubility of carboxylic acids in water and bad abrasion resistance of formed layer.

5 Artículos
Acceso abierto

Study of diffusion processes in the oxide layer of zirconium alloys

Publicado en línea: 19 Mar 2016
Páginas: 1 - 5

Resumen

Abstract

In the active zone of a nuclear reactor where zirconium alloys are used as a coating material, this material is subject to various harmful impacts. During water decomposition reactions, hydrogen and oxygen are evolved that may diffuse through the oxidic layer either through zirconium dioxide (ZrO2) crystals or along ZrO2 grains. The diffusion mechanism can be studied using the Ion Beam Analysis (IBA) method where nuclear reaction 18O(p,α)15N is used. A tube made of zirconium alloy E110 (with 1 wt. % of Nb) was used for making samples that were pre-exposed in UJP PRAHA a.s. and subsequently exposed to isotopically cleansed environment of H218O medium in an autoclave. The samples were analysed with gravimetric methods and IBA methods performed at the electrostatic particle accelerator Tandetron 4130 MC in the Nucler Physics Institute of the CAS, Řež. With IBA methods, the overall thicknesses of corrosion layers on the samples, element composition of the alloy and distribution of oxygen isotope 18O in the corrosion layer and its penetration in the alloy were identified. The retrieved data shows at the oxygen diffusion along ZrO2 grains because there are two peaks of 18O isotope concentrations in the corrosion layer. These peaks occur at the environment-oxide and oxide-metal interface. The element analysis identified the presence of undesirable hafnium.

Acceso abierto

Electrochemical deposition of coatings of highly entropic alloys from non-aqueous solutions

Publicado en línea: 19 Mar 2016
Páginas: 6 - 12

Resumen

Abstract

The paper deals with electrochemical deposition of coatings of highly entropic alloys. These relatively new materials have been recently intensively studied. The paper describes the first results of electrochemical coating with highly entropic alloys by deposition from non-aqueous solutions. An electrochemical device was designed and coatings were deposited. The coatings were characterised with electronic microscopy scanning, atomic absorption spectrometry and X-ray diffraction methods and the combination of methods of thermic analysis of differential scanning calorimetry and thermogravimetry.

Acceso abierto

The influence of total reinforcement anchorage length on misinterpretation of the impact of hot-dip galvanised steel corrosion on its bond strength with concrete

Publicado en línea: 19 Mar 2016
Páginas: 13 - 20

Resumen

Abstract

To begin with, the intorduction of this paper summarises literature sources that wrongly interpret results of the bond strength between hot-dip galvanised reinforcements and concrete. The influence of the total reinforcement anchorage length on the bond strength results assessment was studied in detail. The numeric analysis of beam models with various testing anchorage lengths (the analysis input data comprised the results of previous bond strength tests carried out in a laboratory) unambiguously confirmed that when the bond strength between concrete and hot-dip galvanised reinforcement with a sufficient test anchorage length is tested in a beam test, the negative impact of the coating corrosion on bond strength with concrete may be biased. It is more objective to test bond strength with concrete in a pull-out test where a very short test reinforcement anchorage length is set out as a standard.

Acceso abierto

Operation corrosion test of austenitic steel bends for supercritical coal boilers

Publicado en línea: 19 Mar 2016
Páginas: 21 - 27

Resumen

Abstract

Corrosion tests of both annealed and not annealed bends of HR3C and S304H steels in operation conditions of black and brown coal combustion boilers in EPRU and EDE. After a long-term exposure, the samples were assessed gravimetrically and metallographically. The comparison of annealed and unannealed states showed higher corrosion rates in the annealed state; corrosion of the sample surface did not essentially differ for compression and tensile parts of the beams. Detailed assessment of both steels is described in detail in this study.

Acceso abierto

Protection of historical lead against acetic acid vapour

Publicado en línea: 19 Mar 2016
Páginas: 28 - 34

Resumen

Abstract

Historical lead artefacts (small figurines, appliques, bull (metal seal) can be stored in depository and archives in inconvenient storage conditions. The wooden show-case or paper packagings release volatile organic compound to the air during their degradation. These acids, mainly acetic acid are very corrosive for lead. The thin layer of corrosion products which slows atmospheric corrosion is formed on lead surface in atmospheric condition. In presence of acetic acid vapour the voluminous corrosion products are formed and fall off the surface. These corrosion products do not have any protection ability. The lead could be protected against acid environment by layer of “metal soup” which is formed on surface after immersion in solution of salt of carboxylic acid for 24 hours. The solutions of acids (with vary long of carbon chain) and their salts are examined. Longer carbon chain provides better efficiency convers layer. The disadvantages are low solubility of carboxylic acids in water and bad abrasion resistance of formed layer.

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