1,720,961 research outputs found
Effect of printing orientation on mechanical properties of components in stainless steel obtained using the Bound Metal Deposition technology
No full textThe present work aims at studying and analyzing the influence of process parameters on performances of 3D printed components obtained using the Bound Metal Deposition technology. Bound Metal Deposition is one of the latest technologies for metals 3D printing. It consists in an extrusion process in which the parts are fabricated layer-by-layer through the deposition of metal powder held together by wax and polymer binder. After printing, binder is removed using a solvent, and the additively manufactured parts are sintered for their consolidation at temperatures reaching 1400°C for about 40 hours. Tensile specimens in 17-4 PH stainless steel were additively manufactured imposing different printing orientations in order to evaluate the effect of growth orientation angle on the mechanical properties of 3D printed parts. Results have demonstrated that the printing orientation greatly affects the mechanical performances of 3D printed components
Application of Resistometric Sensors in Investigation of Zinc Corrosion in Simulated Concrete Environments
Full text linkThe aim of this paper was to investigate the corrosion behaviour of zinc in simulated concrete solutions using resistometric sensors and to describe the kinetics of zinc corrosion. The sensors provide corrosion data information in real time; thus, it is a useful technique for observing zinc corrosion behaviour in concrete environments. The replacement of carbon steel rebar by galvanized steel in concrete is a discussable topic with contradictory results in the literature presented in the introduction. In our case, zinc resistometric sensors were used, and they showed results in good agreement with other techniques, such as corrosion potential monitoring and EIS measurements. According to our results, zinc is able to passivate in a simulated concrete solution and even in a simulated carbonated solution. The corrosion rate was reduced by almost 40 times, during the active to passive transition. The zinc remains passive even in simulated concrete solutions contaminated with low levels of chloride ions up to 0.9 wt.%
Characterization of Microstructure and Localized Corrosion Resistance of Heat-Treated 17-4 PH Stainless Steel Fabricated by Material Extrusion
Full text linkThe quality, reproducibility, and reliability of additive-manufactured parts strongly depend on optimizing printing parameters and post-processing treatments. This study evaluates the effects on the microstructure and corrosion resistance properties of solution annealing and aging heat treatments performed on 17-4 PH stainless steel samples fabricated with different build-up orientations using a material extrusion technology: the Bound Metal DepositionTM. The chemical composition and microstructures were determined using X-ray diffraction, chemical etching, optical microscopy, and scanning electron microscopy. The corrosion resistance properties in neutral sodium chloride electrolytes were investigated through cyclic potentiodynamic polarization and open circuit potential monitoring and analysis. The findings demonstrated that the solution annealing heat treatment remarkably enhanced the overall corrosion resistance properties of the samples. The improvement was attributed to the growth of the ferritic phase along the grain boundaries of the martensitic matrix and a finer dispersion of copper precipitates. The aging heat treatment performed after solution annealing enhanced the ferritic phase development, resulting in a further improvement of the localized corrosion resistance properties
Study of the localized corrosion resistance of AA5083 aluminium alloy subjected to severe plastic deformation
No full textIn this work the localized corrosion behaviour of AA5083 aluminium alloy, subjected to severe plastic deformation (SPD) through the Equal Channel Angular Pressing technique (ECAP), useful to obtain an ultrafine microstructure, was studied. This process improves mechanical properties and modifies the microstructure of the alloy. With more details, the localized corrosion resistance of the AA5083 alloy subjected to thermal and cryogenic treatments and finally to ECAP was evaluated. Electrochemical characterization of this alloy was performed in aqueous solution 0.1 M of NaCl and pH 6.5, at room temperature, by means of cyclic potentiodynamic polarizations and potentiostatic polarizations for evaluating metastable pitting events. All tests were performed in deaerated conditions. The experimental results show that ECAP tends to increase AA5083 alloy localized corrosion susceptibility
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Study of corrosion resistance of 17-4 PH stainless steel as-sintered and heat-treated samples manufactured by Bound Metal DepositionTM
No full textThe corrosion resistance of 17-4 PH stainless steel samples additive manufactured by Bound Metal DepositionTM (BMD) has been investigated in neutral sodium chloride environments. The methods used in this study were based on longterm monitoring of the Open Circuit Potential and afterwards recording of Cyclic Potentiodynamic Polarization curves in the same electrolytic solution. The electrochemical investigations have been carried out on 17-4 PH wrought samples and on BMD as-sintered and H900 heat-treated samples. The BMD samples had different build-up orientations with respect to the build plate. The results showed that the susceptibility to localized corrosion of the 3D printed samples is higher than the wrought 17-4 PH, although the breakdown potential on the anodic curves was even higher in some of the former than the latter. A better corrosion behavior of the BMD printed samples was observed after heat treatment, in particular for those with build-up orientation of 0° and 45°
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