Stress influence on high temperature oxide scale growth: modeling and investigation on a thermal barrier coating system.

International audienceIn thermal barrier coating (TBC) systems, an oxide layer develops at high temperature below the ceramic coating, leading at long term to the mechanical failure of the structure upon cooling. This study investigates a mechanism of stress-affected oxidation likely to induce the growth of a non-uniform oxide scale detrimental to the TBC lifetime. A continuum thermodynamics formulation is derived accounting for the influence of the stress and strain situation at the sharp metal/oxide phase boundary on the local oxidation kinetics. It specially includes the contributions of the large volumetric strain and the mass consumption associated with metal oxidation. A continuum mechanics/mass diffusion framework is used along with the developed formulation for the interface evolution to study the growth of an oxide layer coupled with local stress development. The implementation of the model has required the development of a specific simulation tool, based on a finite element method completed with an external routine for the phase boundary propagation. Results on an electron-beam physical vapor deposited (EB-PVD) TBC case are presented. The processes resulting in a non-uniform oxide scale growth are analyzed and the main influences are discussed

A physics-based life prediction methodology for thermal barrier coating systems

A novel mechanistic approach is proposed for the prediction of the life of thermal barrier coating (TBC) systems. The life prediction methodology is based on a criterion linked directly to the dominant failure mechanism. It relies on a statistical treatment of the TBC's morphological characteristics, non-destructive stress measurements and on a continuum mechanics framework to quantify the stresses that promote the nucleation and growth of microcracks within the TBC. The last of these accounts for the effects of TBC constituents' elasto-visco-plastic properties, the stiffening of the ceramic due to sintering and the oxidation at the interface between the thermally insulating yttria stabilized zirconia (YSZ) layer and the metallic bond coat. The mechanistic approach is used to investigate the effects on TBC life of the properties and morphology of the top YSZ coating, metallic low-pressure plasma sprayed bond coat and the thermally grown oxide. Its calibration is based on TBC damage inferred from non-destructive fluorescence measurements using piezo-spectroscopy and on the numerically predicted local TBC stresses responsible for the initiation of such damage. The potential applicability of the methodology to other types of TBC coatings and thermal loading conditions is also discussed

Modelling stress-diffusion controlled phase transformations : application to stress corrosion cracking

National audienceStress Corrosion Cracking (SCC) represents a significant cause of failure in pressurised water reactors and many efforts have been made to address this problem [1]. It involves the combined action of the environment, mechanical stresses and material properties on the damage of engineering components. Current SCC models developed to predict crack growth behaviour or SCC susceptibility criteria do not fully incorporate the complex multiphysical processes that occur during oxidation at the scale of the microstructure. The aim of the work is to formulate a multi-physics modelling framework based on continuum thermodynamics able to describe the growth of an oxide film on a polycrystalline material using the phase field method

Determinación del rendimiento y del coeficiente global de pérdida de un ramal colector plástico mediante un método calorimétrico simple

Se exponen en el presente artículo los resultados obtenidos para el valor del coeficiente global de pérdida térmica K, y el rendimiento η, de un ramal colector plástico. En la determinación experimental el ramal colector fue sometido a ensayos calorimétricos simples bajo diferentes condiciones: convección natural, circulación forzada y con la radiación solar como fuente de calor. Se plantea el modelo teórico base para el análisis de los resultados experimentales y su aplicabilidad a las particularidades del sistema ensayado.The determination of the overall heat loss coefficient K, and the efficiency η, for a single line plastic collector is presented. The collector was the object of simple calorimetric tests under varying conditions: natural convection, forced convection and with solar radiation as heat source. The theoretical model used in the analysis of the experimental data and its applicability to our system is stated as well.Tema 3: Energía solar, aplicaciones térmicas y químicas.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

De la permisibilidad a la restricción. Un análisis de la incidencia de los condicionantes sistémicos sobre la política exterior del kirchnerismo (2003-2015)*

There is a broad consensus on the importance that the domestic constraints have had on the design of foreign policy during the governments of Néstor and Cristina Kirchner. In line with this diagnosis, systemic constraints have tended to be neglected in the studies related to the argentinean foreign policy during this period. Therefore, in this work, we intend to fill part of that gap. For this reason, by way of hypothesis, we argue that the systemic factors were not constant in the twelve years of Kirchner's administration, but that they changed from a permissive profile to a more restrictive one in the second term of Cristina Fernández. This dynamic had an impact on multiple dimensions of foreign policy, but was more evident in the economic sphere.Existe un consenso amplio sobre la importancia que los condicionantes domésticos tuvieron en el diseño de la política exterior durante los gobiernos de Néstor y Cristina Kirchner. En consonancia con ese diagnóstico los condicionantes sistémicos han tendido a ser dejados de lado en los estudios referidos a la política exterior argentina durante esa etapa. Por ello, en este trabajo, pretendemos cubrir parte de esa laguna. Consecuentemente argumentamos, a modo de hipótesis, que los condicionantes sistémicos no fueron constantes en los doce años de gestión kirchnerista, sino que mudaron desde un perfil permisivo a uno más restrictivo en el segundo mandato de Cristina Fernández. Esta dinámica tuvo impacto sobre múltiples dimensiones de la Política Exterior, pero fue más evidente en el ámbito económic

De la permisibilidad a la restricción. Un análisis de la incidencia de los condicionantes sistémicos sobre la política exterior del kirchnerismo (2003-2015)

Existe un consenso amplio sobre la importancia que los condicionantes domésticos tuvieron en el diseño de la política exterior durante los gobiernos de Néstor y Cristina Kirchner. En consonancia con ese diagnóstico los condicionantes sistémicos han tendido a ser dejados de lado en los estudios referidos a la política exterior argentina durante esa etapa. Por ello, en este trabajo, pretendemos cubrir parte de esa laguna. Consecuentemente argumentamos, a modo de hipótesis, que los condicionantes sistémicos no fueron constantes en los doce años de gestión kirchnerista, sino que mudaron desde un perfil permisivo a uno más restrictivo en el segundo mandato de Cristina Fernández. Esta dinámica tuvo impacto sobre múltiples dimensiones de la Política Exterior, pero fue más evidente en el ámbito económico.There is a broad consensus on the importance that the domestic constraints have had on the design of foreign policy during the governments of Néstor and Cristina Kirchner. In line with this diagnosis, systemic constraints have tended to be neglected in the studies related to the argentinean foreign policy during this period. Therefore, in this work, we intend to fill part of that gap. For this reason, by way of hypothesis, we argue that the systemic factors were not constant in the twelve years of Kirchner's administration, but that they changed from a permissive profile to a more restrictive one in the second term of Cristina Fernández. This dynamic had an impact on multiple dimensions of foreign policy, but was more evident in the economic sphere.Fil: Actis, Esteban. Universidad Nacional de Rosario; ArgentinaFil: Busso, Anabella. Universidad Nacional de Rosario; ArgentinaFil: Calderón, Emilse. Universidad Nacional de Rosario; ArgentinaFil: Zelicovich, Julieta. Universidad Nacional de Rosario; Argentin

Determinación del rendimiento y del coeficiente global de pérdida de un ramal colector plástico mediante un método calorimétrico simple

Se exponen en el presente artículo los resultados obtenidos para el valor del coeficiente global de pérdida térmica K, y el rendimiento η, de un ramal colector plástico. En la determinación experimental el ramal colector fue sometido a ensayos calorimétricos simples bajo diferentes condiciones: convección natural, circulación forzada y con la radiación solar como fuente de calor. Se plantea el modelo teórico base para el análisis de los resultados experimentales y su aplicabilidad a las particularidades del sistema ensayado.The determination of the overall heat loss coefficient K, and the efficiency η, for a single line plastic collector is presented. The collector was the object of simple calorimetric tests under varying conditions: natural convection, forced convection and with solar radiation as heat source. The theoretical model used in the analysis of the experimental data and its applicability to our system is stated as well.Tema 3: Energía solar, aplicaciones térmicas y químicas.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Modelos de desarrollo e inserción internacional: aportes para el análisis de la política exterior argentina desde la redemocratización: 1983-2011, actores y temas de agenda.

En este e-book titulado “Modelos de desarrollo e inserción internacional. Aportes para el análisis de la política exterior argentina desde la redemocratización (1983-2011). Actores y temas de agenda”se sistematizan parte de los resultados obtenidos a través del proyecto de investigación “Modelos de desarrollo e inserción internacional. Aportes para el análisis de la política exterior argentina desde la redemocratización (1983-2011)”, financiado por la Agencia Nacional de Promoción Científica y Tecnológica (ANCyT) bajo el código PICT-2011-0681.Fil: Busso, Anabella. Universidad Nacional de Rosario. Facultad de Ciencia Política y Relaciones Internacionales; Argentina.Fil: Actis, Esteban. Universidad Nacional de Rosario. Facultad de Ciencia Política y Relaciones Internacionales; Argentina.Fil: Ceppi, Natalia. Universidad Nacional de Rosario. Facultad de Ciencia Política y Relaciones Internacionales; Argentina.Fil: Fabani, Ornela. Universidad Nacional de Rosario. Facultad de Ciencia Política y Relaciones Internacionales; Argentina.Fil: Fernández Alonso, José. Universidad Nacional de Rosario. Facultad de Ciencia Política y Relaciones Internacionales; Argentina.Fil: Lorenzini, María Elena. Universidad Nacional de Rosario. Facultad de Ciencia Política y Relaciones Internacionales; Argentina.Fil: Novello, María Rocío. Universidad Nacional de Rosario. Facultad de Ciencia Política y Relaciones Internacionales; Argentina.Fil: Paredes Rodríguez, Rubén. Universidad Nacional de Rosario. Facultad de Ciencia Política y Relaciones Internacionales; Argentina.Fil: Simonoff, Alejandro. Universidad Nacional de La Plata; Argentina.Fil: Zelicovich, Julieta. Universidad Nacional de Rosario. Facultad de Ciencia Política y Relaciones Internacionales; Argentina

Infrared two-colour diagrams for AGB stars using AKARI, MSX, IRAS and NIR data

Using a revised version of the catalog of AGB stars by Suh & Kwon (2009), we present various infrared two-colour diagrams (2CDs) for 3003 O-rich, 1168 C-rich, 362 S-type and 35 silicate carbon stars in our Galaxy. For each object in the new catalog, we cross-identify the AKARI, MSX and 2MASS counterparts by finding the nearest one from the position information in the IRAS PSC. For the large sample of AGB stars, we present infrared two-colour diagrams using IRAS (PSC), AKARI (PSC and BSC), MSX (PSC) and near infrared (K and L bands; including 2MASS data at KS band) data for different classes of AGB stars based on the chemistry of the dust shell and/or the central star. The infrared 2CDs of AGB stars can provide useful information about the structure and evolution of the dust envelopes as well as the central stars. On the 2CDs, we plot tracks of the theoretical radiative transfer model results with increasing dust shell optical depths. Comparing the observations with the theoretical models on the new 2CDs, we find that the basic model tracks roughly coincide with the densely populated observed points. Generally, we can explain the observations of O-rich and C-rich AGB stars on the various 2CDs with the theoretical models using dust opacity functions of amorphous silicate, amorphous carbon, SiC and corundum. For O-rich AGB stars, we find that the models using corundum as well as silicate can improve the fit with the observations