Characterisation of PVD-TiN coated austempered ductile iron: Effects of nodule count and austempering temperature

In this work PVD-TiN coatings are deposited on ADI substrates austempered at 280 and 360°C, with nodule counts varying between 490 and 1 100 nod/mm2. The deposition is performed at 300°C by the arc ion plating technique. The effects of the substrates' microstructure on the characteristics of the coatings and the possible changes in ausferritic microstructure owing to the effects of the deposition process are evaluated. The existing phases, preferred orientation, film thickness, hardness, Young's modulus, surface topography and adhesion of each coated sample are determined. A metallographic characterisation of the ausferritic matrices and determination of the retained austenite content are performed before and after deposition. The results obtained indicate that PVD-TiN coatings feature a preferred orientation of (111) planes parallel to the surface and film thicknesses of about 2m m. Knoop hardness is influenced by the substrates characteristics, the values range from 1 700 to 2 100 HK0.015. Nanohardness values are close to 25 GPa, while Young's modulus shows some scattering (323 to 336 GPa). The surface topography is dependent on the microstructure of the substrates and the surface preparation method employed as well as on the deposition process used. The adhesion strength quality of the coatings, according to the Rockwell-C adhesion test, can be related to HF1-HF2 and is affected neither by the hardness differences between the different substrates nor by the nodule count variation. After the coating process, the microstructure of ADI substrates only suffers negligible changes and the amount of retained austenite decreases slightly.Fil: Colombo, Diego Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Echeverría, María D.. Universidad Nacional de Mar del Plata; ArgentinaFil: Moncada, Osvaldo Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Massone, Juan Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Symplectic Cuts and Projection Quantization

The recently proposed projection quantization, which is a method to quantize particular subspaces of systems with known quantum theory, is shown to yield a genuine quantization in several cases. This may be inferred from exact results established within symplectic cutting.Comment: 12 pages, v2: additional examples and a new reference to related wor

Surface alterations produced in grinding of austempered ductile iron

The technological advances achieved in recent decades have allowed to obtain cast parts of ductile iron with no metallurgical defects and of complex shapes and dimensions very close to the final ones. Heat treatments have enabled to obtain ADI within a wide range of mechanical properties. After properly choosing the processing variables, the most suitable combination of strength and toughness can be attained for each application. When restrictive dimensional or shape accuracy is required, a high precision machining process, such as grinding, is used. This process induces significant temperature gradients and surface plastic deformations which could affect the surface characteristics. The aim of this paper is to analyze the effects of grinding on power consumption, surface characteristics, roughness and distortion on ADI plates grade 2 and 5. The results indicate that it is possible to achieve excellent surface finishes with moderate power consumption and low residual stresses and distortions.Fil: Sosa, Amadeo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación En Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Echeverría, M. D.. Universidad Nacional de Mar del Plata. Facultad de Ingenieria. Departamento de Mecanica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentin

Systematic Review Approach to identifying key trends in adaptation governance at the supranational level

In this paper authors have analyzed peer-reviewed literature on adaptation governance focused on food security at the supranational level. A total of 281 papers were collected, of which 52 met our focus. We used 10 criteria (and 74 sub-criteria) to categorize the included papers. With research presented in these papers as our focus, we looked at key aspects of food security explored, identified types of governance measures and major challenges, and finally developed an understanding of the location of the research teams and involved countries. Overall, we found that the supranational focus in the context of adaptation governance on food security is not prevalent in current peer-reviewed literature—only approximately 16 per cent of the papers focus on this topic. In terms of the identified trends, there was a strong focus on developed countries and research led by teams from these countries; the governance systems aimed to prepare for a range of climate change impacts; and finally, there was limited interest in exploring the role of regional agencies in adaptation governance. In terms of future research needs, there is a strong need to develop processes for the integration of diverse sectors and issues when designing policies on food security in the context of climate change. It is also important to improve the skills and opportunities of research teams in the Global South to engage effectively in research on food security and governance

Multivector Field Formulation of Hamiltonian Field Theories: Equations and Symmetries

We state the intrinsic form of the Hamiltonian equations of first-order Classical Field theories in three equivalent geometrical ways: using multivector fields, jet fields and connections. Thus, these equations are given in a form similar to that in which the Hamiltonian equations of mechanics are usually given. Then, using multivector fields, we study several aspects of these equations, such as the existence and non-uniqueness of solutions, and the integrability problem. In particular, these problems are analyzed for the case of Hamiltonian systems defined in a submanifold of the multimomentum bundle. Furthermore, the existence of first integrals of these Hamiltonian equations is considered, and the relation between {\sl Cartan-Noether symmetries} and {\sl general symmetries} of the system is discussed. Noether's theorem is also stated in this context, both the ``classical'' version and its generalization to include higher-order Cartan-Noether symmetries. Finally, the equivalence between the Lagrangian and Hamiltonian formalisms is also discussed.Comment: Some minor mistakes are corrected. Bibliography is updated. To be published in J. Phys. A: Mathematical and Genera

Structure and bonding of halonium compounds

The geometrical parameters and the bonding in [D···X···D]+ halonium compounds, where D is a Lewis base with N as the donor atom and X is Cl, Br, or I, have been investigated through a combined structural and computational study. Cambridge Structural Database (CSD) searches have revealed linear and symmetrical [D···X···D]+ frameworks with neutral donors. By means of density functional theory (DFT), molecular electrostatic potential (MEP), and energy decomposition analyses (EDA) calculations, we have studied the effect of various halogen atoms (X) on the [D···X···D]+ framework, the effect of different nitrogen-donor groups (D) attached to an iodonium cation (X = I), and the influence of the electron density alteration on the [D···I···D]+ halonium bond by variation of the R substituents at the N-donor upon the symmetry, strength, and nature of the interaction. The physical origin of the interaction arises from a subtle interplay between electrostatic and orbital contributions (σ-hole bond). Interaction energies as high as 45 kcal/mol suggest that halonium bonds can be exploited for the development of novel halonium transfer agents, in asymmetric halofunctionalization or as building blocks in supramolecular chemistry

Las obras de ingeniería civil, base fundamental para cambios sociales

Civil works are of vital importance for the development of individuals’ lives since they generate changes in the natural environment in response to a specific need of a certain group of people. Each one of these constructions brings with it a social impact in the face of concrete activities. Factors such as the economy, demography, and culture allow us to talk about positive and negative impacts. Finally, the awareness of civil engineers regarding the responsibility of safeguarding the life of other individuals becomes fundamental; executing projects with excellent planning is the first step to avoid the diverse difficulties in which a work may be involved, but more important than this, imparting the premise of a correct exercise of civil engineering seems to be a mandatory need.Las obras civiles son de vital importancia para el desarrollo de la vida de los individuos, ya que estas generan cambios en el entorno natural respondiendo a una necesidad específica de un determinado grupo de personas. Cada una de estas construcciones trae consigo un impacto social frente a actividades concretas. Factores como la economía, la demografía y la cultura permiten hablar sobre los impactos positivos y negativos. Finalmente la concientización hacia los ingenieros civiles en cuanto a la responsabilidad de salvaguardar la vida de los demás individuos se torna fundamental, ejecutar proyectos con excelente planeación es el primer paso para evitar las diversas dificultades en las cuales se puede ver involucrada una obra, pero más importante que esto, impartir la premisa de un correcto ejercicio de la ingeniería civil parece ser una necesidad de obligatorio cumplimiento

Comportamiento mecánico de ADI tratada superficialmente mediante la aplicación de recubrimientos PVD de baja temperatura

En este trabajo se aplican recubrimientos PVD de TiN y CrN sobre ADI y se analiza la influencia del material del recubrimiento sobre las propiedades mecánicas del producto ADI recubierto. Se analiza también, el efecto del proceso de deposición sobre la microestructura de los sustratos. Los recubrimientos se aplican en un reactor industrial mediante la técnica de plateado iónico con arco catódico, utilizando parámetros de proceso específicamente seleccionados para este material. Se determinan fases presentes, orientación preferencial, topografía superficial, espesor de película, dureza, tensiones residuales, adherencia y coeficiente de fricción de las muestras recubiertas. Además, se determina la cantidad de austenita retenida presente en los sustratos antes y después de las deposiciones. Los resultados obtenidos muestran que los recubrimientos de TiN y CrN aplicados sobre muestras de ADI a una temperatura de 300ºC y con tiempos de deposición de hasta 180 min presentan muy buenas características en cuanto a espesor de película, dureza, tensiones residuales y adherencia, sin producir deterioro de la microestructura ausferrítica. Los procesos de deposición modifican la topografía superficial de las muestras, produciendo un aumento de la rugosidad media. Las muestras recubiertas con TiN presentan mayores durezas y tensiones residuales. Las muestras sin recubrir y recubiertas con TiN muestran coeficientes de fricción similares, mientras que las muestras recubiertas con CrN coeficientes significativamente inferiores. Los ensayos de deslizamiento no produjeron la fractura y/o delaminación de los recubrimientos en ningún caso.Fil: Colombo, Diego Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina; Universidad Nacional de Mar del Plata; Argentina;Fil: Echeverría, María D.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina; Universidad Nacional de Mar del Plata; Argentina;Fil: Massone, Juan Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina; Universidad Nacional de Mar del Plata; Argentina

Scanning electron microscopy of the oral apparatus and buccopharyngeal cavity of Atelognathus salai larvae (Anura, Neobatrachia)

The aim of this study is to describe the horny structures of the buccal apparatus and buccopharyngeal cavity of A. salai by means ofscanning electron microscopy (SEM), and to compare them to those of the other known species of Atelognathus and related genera

On the k-Symplectic, k-Cosymplectic and Multisymplectic Formalisms of Classical Field Theories

The objective of this work is twofold: First, we analyze the relation between the k-cosymplectic and the k-symplectic Hamiltonian and Lagrangian formalisms in classical field theories. In particular, we prove the equivalence between k-symplectic field theories and the so-called autonomous k-cosymplectic field theories, extending in this way the description of the symplectic formalism of autonomous systems as a particular case of the cosymplectic formalism in non-autonomous mechanics. Furthermore, we clarify some aspects of the geometric character of the solutions to the Hamilton-de Donder-Weyl and the Euler-Lagrange equations in these formalisms. Second, we study the equivalence between k-cosymplectic and a particular kind of multisymplectic Hamiltonian and Lagrangian field theories (those where the configuration bundle of the theory is trivial).Comment: 25 page