Analysis of the microstructure and mechanical properties of Titanium-based composites reinforced by secondary phases and B4C particles produced via direct hot pressing

In the last decade, titanium metal matrix composites (TMCs) have received considerable attention thanks to their interesting properties as a consequence of the clear interface between the matrix and the reinforcing phases formed. In this work, TMCs with 30 vol % of B4C are consolidated by hot pressing. This technique is a powder metallurgy rapid process. Incorporation of the intermetallic to the matrix, 20 vol % (Ti-Al), is also evaluated. Here, the reinforcing phases formed by the reaction between the titanium matrix and the ceramic particles, as well as the intermetallic addition, promote substantial variations to the microstructure and to the properties of the fabricated composites. The influences of the starting materials and the consolidation temperature (900 C and 1000 C) are investigated. By X-ray diffraction, scanning and transmission electron microscopy analysis, the in-situ-formed phases in the matrix and the residual ceramic particles were studied. Furthermore, mechanical properties are studied through tensile and bending tests in addition to other properties, such as Young’s modulus, hardness, and densification of the composites. The results show the significant effect of temperature on the microstructure and on the mechanical properties from the same starting powder. Moreover, the Ti-Al addition causes variation in the interface between the reinforcement and the matrix, thereby affecting the behaviour of the TMCs produced at the same temperature.Junta de Andalucía TIC-752

Influence of sintering temperature on the microstructure and mechanical properties of in situ reinforced titanium composites by inductive hot pressing

This research is focused on the influence of processing temperature on titanium matrix composites reinforced through Ti, Al, and B4C reactions. In order to investigate the effect of Ti-Al based intermetallic compounds on the properties of the composites, aluminum powder was incorporated into the starting materials. In this way, in situ TixAly were expected to form as well as TiB and TiC. The specimens were fabricated by the powder metallurgy technique known as inductive hot pressing (iHP), using a temperature range between 900 °C and 1400 °C, at 40 MPa for 5 min. Raising the inductive hot pressing temperature may affect the microstructure and properties of the composites. Consequently, the variations of the reinforcing phases were investigated. X-ray diffraction, microstructural analysis, and mechanical properties (Young’s modulus and hardness) of the specimens were carried out to evaluate and determine the significant influence of the processing temperature on the behavior of the compositesJunta de Andalucía. TIC-752

Agitation in a hospitalized adult. Standardized care plan

La agitación psicomotriz en un paciente adulto hospitalizado es una de las situaciones más estresantes con las que se puede encontrar el personal de enfermería en su trabajo diario. El conocer su manejo, las intervenciones a realizar y el proporcionar en todo momento la seguridad del paciente y la de los profesionales que estén implicados constituye la primera pauta de actuación. Debemos recordar que la agitación psicomotriz no es sólo característica de los enfermos mentales, hay causas orgánicas que pueden ocasionar estos estados de alteración. Por lo que el conocimiento de estas causas pueden prevenir o minimizar futuras complicaciones. Con este artículo se pretender guiar al personal de enfermería que trabajan en las plantas de hospitalización en el cuidado de estos pacientes y elaborar unas recomendaciones básicas y pautas de actuación para la creación de unos planes estandarizados para estos enfermos. Para ello se utilizará la taxonomía enfermera NANDA, NIC, NOC.Psychomotor agitation in a hospitalized adult patient is one of the most stressful situation with which you can find nurses in the their daily work. Knowing its management, interventions to make and always provide patient safety and the professionals who are involved is the first tool of intervention. We must remember that the psychomotor agitation is not only characteristic of the mentally ill, there are organic causes that can cause these altered states. As knowledge of these causes can prevent or minimize future complications. This article is trying to guide the nurses working in hospital wards in the care of these patients and developed some basic recommendations and guidelines for action for the creation of standardized plans for these patients. This will draw the taxonomy nurse NANDA, NIC, NOC

Sell recommendations by analysts in response to business communication strategies concerning the Sustainable Development Goals and the SDG Compass

This paper has two main aims: firstly, to examine the effect of pessimistic (sell) recommendations made by analysts to investors on the implementation of business communication strategies in accordance with the Sustainable Development Goals (SDGs), through the adoption of the SDG Compass. Secondly, it considers the possible corrective effect produced by these strategies on analysts’ recommendations, i.e. modifying their perception of corporate social responsibility (CSR) as an agency cost. Based on a sample of 989 international companies which disclose CSR information, obtained by merging the Global Reporting Initiative (GRI) and Thomson Reuters databases, our analysis of the results obtained shows that the companies receiving most sell recommendations were among the first to adopt the SDG Compass in a given year or in the year immediately following it. Nevertheless, this effect is limited, because the long-term implementation of CSR strategies has a relatively trivial impact on analysts’ recommendations, since there is little likelihood of change in these strategies

Evaluación del bienestar animal mediante indicadores conductuales en una planta de beneficio bovino en Boyacá, Colombia

            The aim of this study was to determine the behaviour and management practices related to the welfare of the animals destined for slaughter in an abattoir in the city of Sogamoso, Boyacá, Colombia. Behavioural and management indicators were evaluated before, during and after desensitization in 100 cattle aged 1 to 5 years. The evaluation parameters were classified as excellent, acceptable, not acceptable and problem, according to a system proposed by the American Meat Institute. It was found that 11% of the animals suffered falls and 17% slipped, 23% vocalized and that in 61% of the animals the electric prod or another instrument was used for their mobilization, these facts being considered as problem from a wellness viewpoint. In the desensitization process, 93% correct stunning was obtained with a single shot and stunning failed in 7%; however, in the floor and the bleeding rail, some recovered sensitivity, and therefore, 87% were completely desensitized and 13% incorrectly desensitized as they showed signs of incorporation, vocalizations or rhythmic breathing. It is concluded that slaughterhouse presented weaknesses that affect animal welfare related to the lack of management of processes that are routinely carried out.            El presente estudio tuvo como objetivo determinar las conductas y prácticas de manejo relacionadas al bienestar de los animales destinados a sacrificio en una planta de beneficio de ganado bovino en la ciudad de Sogamoso, Boyacá, Colombia. Se evaluaron indicadores conductuales y de manejo antes, durante y después de la insensibilización en 100 bovinos con edades de 1 a 5 años. Los parámetros de evaluación fueron clasificados como excelente, aceptable, no aceptable y problema, de acuerdo con un sistema propuesto por el Instituto Americano de la Carne. Se encontró que el 11% de los animales sufrieron caídas, 17% resbalones, 23% tuvieron vocalizaciones; además, en el 61% de los animales se utilizó la picana eléctrica u otro instrumento para su movilización, siendo estos problemas considerados como graves desde el punto de vista de bienestar. En el proceso de insensibilización se obtuvo un 93% de aturdimiento correcto, con un solo disparo y 7% de aturdimiento fallido; sin embargo, en el piso y el riel de desangrado, algunos recuperaron sensibilidad siendo el resultado final de 87% completamente insensibilizados y 13% incorrectamente insensibilizados ya que presentaron signos de incorporación, vocalizaciones o con respiración rítmica. Se concluye que la planta de beneficio presentó debilidades que afectan el bienestar animal relacionadas a faltas en el manejo de los procesos rutinarios

Study of the Influence of TiB Content and Temperature in the Properties of In Situ Titanium Matrix Composites

This work focuses on the study of the microstructure, hardening, and stiffening effect caused by the secondary phases formed in titanium matrices. These secondary phases originated from reactions between the matrix and boron particles added in the starting mixtures of the composites. Not only was the composite composition studied as an influencing factor in the behaviour of the composites, but also different operational temperatures. Three volume percentages of boron content were tested (0.9 vol %, 2.5 vol %, and 5 vol % of amorphous boron). The manufacturing process used to produce the composites was inductive hot pressing, which operational temperatures were between 1000 and 1300º C. Specimens showed optimal densification. Moreover, microstructural studies revealed the formation of TiB in various shapes and proportions. Mechanical testing confirmed that the secondary phases had a positive influence on properties of the composites. In general, adding boron particles increased the hardness and stiffness of the composites; however rising temperatures resulted in greater increases in stiffness than in hardnes

Effect of processing atmosphere and secondary operations on the mechanical properties of additive manufactured AISI 316L stainless steel by Plasma Metal Deposition

Plasma metal deposition (PMD) is an interesting additive technique whereby diverse materials can be employed to produce end parts with complex geometries. This study investigates not only the effects of the manufacturing conditions on the final properties of 316L stainless steel specimens by PMD, but it also affords an opportunity to study how secondary treatments could modify these properties. The tested processing condition was the atmosphere, either air or argon, with the other parameters having previously been optimized. Furthermore, two standard thermal treatments were conducted with the intention of broadening knowledge regarding how these secondary operations could cause changes in the microstructure and properties of 316L parts. To better appreciate and understand the variation of conditions affecting the behavior properties, a thorough characterization of the specimens was carried out. The results indicate that the presence of vermicular ferrite (δ) varied slightly as a consequence of the processing conditions, since it was less prone to appear in specimens manufactured in argon than in air. In this respect, their mechanical properties suffered variations; the higher the ferrite (δ) content, the higher the mechanical properties measured. The degree of influence of the thermal treatment was similar regardless of the processing conditions, which affected the properties based on the heating temperature.European Union Horizon 2020 Program (H2020) grant agreement no 768612Universidad de Sevilla (España) VI PPIT-2019-I.

Processing by Additive Manufacturing Based on Plasma Transferred Arc of Hastelloy in Air and Argon Atmosphere

This research was carried out to determinate the effect of the atmosphere processing conditions (air and argon) and two specific thermal treatments, on the properties of specimens made from the nickel-based alloy Hastelloy C-22 by plasma transferred arc (PTA). Firstly, the additive manufacturing parameters were optimized. Following, two walls were manufactured in air and argon respectively. Afterwards, a determinate number of specimens were cut out and evaluated. Regarding the comparison performed with the extracted specimens from both walls, three specimens of each wall were studied as-built samples. Furthermore, a commonly used heat treatment in Hastelloy, with two different cooling methods, was selected to carry out additional comparisons. In this respect, six additional specimens of each wall were selected to be heat treated to a temperature of 1120 °C for 20 min. After the heat treatment, three of them were cooled down by rapid air cooling (RAC), while the other three were cooled down by water quenching (WQ). In order to study the influence degree of the processing conditions, and how the thermal treatments could modify the final properties of the produced specimens, a detailed characterization was performed. X-ray diffraction and microstructural analyses revealed the phases-presence and the apparition of precipitates, varying the thermal treatment. Moreover, the results obtained after measuring mechanical and tribological properties showed slight changes caused by the variation of the processing atmosphere. The yield strength of the extracted specimens from the two walls achieved values closer to the standards ones in air 332.32 MPa (±21.36 MPa) and in argon 338.14 MPa (±9 MPa), both without thermal treatment. However, the effect of the cooling rate resulted as less beneficial, as expected, reducing the deformation properties of the specimens below 11%, independently of the air or argon manufacturing atmosphere and the cooling rate procedure.Universidad de Sevilla (España) PPIT-2018-I.

Propuesta didáctica en la formación de profesorado para trabajar naturaleza de la ciencia y pensamiento crítico

The social demand to educate scientifically literate citizens becomes crucial to train teachers with an adequate understanding of nature of science (NOS) and development of critical thinking (CT), both essential requirements to instruct these contents in classroom. Because of this aim, in this work, we present the design of a didactical approach (prototype), which is being evaluated and improved through the Design-Based Research methodology. This prototype integrates the inquiry and the history of science through the scientific controversy of spontaneous generation, within an explicit-reflective framework. In order to improve the design and efficacy of the prototype, we are carrying out iterative piloting cycles which, so far, have revealed the importance of adopting an oriented approach in inquiry tasks and an explicit approach in NOS and CT instruction to achieve a successful and significant learning.La demanda social de educar a ciudadanos alfabetizados científicamente convierte en prioritario formar a profesorado con una adecuada comprensión sobre la naturaleza de la ciencia (NDC) y desarrollo de pensamiento crítico (PC), requisitos indispensables para poder impartir dichos contenidos en el aula. Para tal fin, en este trabajo, se presenta el diseño de una propuesta didáctica (prototipo), que está siendo evaluada y mejorada a través de la metodología de investigación enfocada al diseño. Este prototipo integra la indagación y la historia de la ciencia a través de la controversia científica de la generación espontánea, dentro de un marco explícito-reflexivo. Con el fin de mejorar su diseño y eficacia, se están llevando a cabo ciclos iterativos de pilotaje que, hasta el momento, han mostrado la importancia de adoptar un enfoque guiado en las tareas de indagación y de un enfoque explícito en la instrucción sobre la NDC y el PC para lograr un aprendizaje exitoso y significativo