Las bellas artes en la ingeniería de materiales (El proyecto de las campanas)

Los materiales no se estudian únicamente en el grado de Ingeniería de Materiales. Los podemos encontrar en otras ramas del conocimiento, aunque sólo se utilicen algunas de sus propiedades o bien se estudien desde otra perspectiva. La Universitat de Barcelona es una universidad generalista, con cinco campus en la ciudad, alrededor de 65000 estudiantes y con más de 50 departamentos especializados en diferentes áreas del conocimiento, a menudo con escaso conocimiento de las actividades desarrolladas por los demás. Esta falta de contacto entre las áreas puede salvarse por la proximidad de las facultades (en el mismo campus) llegando a desarrollar actividades interdisciplinarias que mejoran las habilidades de aprendizaje de los estudiantes. La actividad que se presenta permite a los estudiantes poner en práctica los conocimientos presentados en distintas asignaturas previas del grado así como algunas de las técnicas discutidas en clase, además de correlacionar sus estudios con diferentes disciplinas

Aprenentatge basat en projectes (ABP) en el marc d'una experiència d'aprenentatge-servei (APS) interuniversitària en enginyeria

Aquest document resum les activitats realitzades en el marc del projecte finançat pel Programa de Millora i Innovació docent de la UB, 2016PID-UB/008.Projecte: 2016PID-UB/008El projecte ha estat la continuació de tres projectes desenvolupats en els respectius cursos anteriors (2012-13, 2013-14, 2014-15) i finançats per la Universidad del País Vasco i la Universitat Jaume I de Castelló, en els que s'havia treballat la implementació de la metodologia d'aprenentatge basat en projectes amb resultats molt satisfactoris. En els cursos anteriors es va implantar aquesta metodologia en diferents assignatures de l’àmbit de la Ciència dels Materials a cada universitat participant (Universidad del País Vasco (EHU), Universitat Jaume I de Castelló (UJI), Universitat de Barcelona (UB), Universidad de Málaga (UMA)), però cadascuna amb un perfil diferent d’estudiant (diferents enginyeries). En cada projecte es va escollir un objecte sobre el qual els estudiants havien de treballar: unes maquinetes d’afaitar, uns bastons per caminar i un pòdium, respectivament. Com l’objecte a estudiar en els darrers projectes va ser el mateix per a totes les universitats, es van poder comparar els resultats obtinguts en cadascuna d’elles en els diferents Wokshops IdM@ti que s’organitzen anualment, s’han presentat en diferents congressos i s’han publicat recentment. D’altra banda, l’origen dels estudiants és diferent, cadascun treballa en el disseny de l’objecte, la selecció de materials i processat, des de diferents punts de vista. Els alumnes de Disseny Industrial (UJI) fan un redisseny del producte; els d’Enginyeria Mecànica (EHU i UMA) estudien els antecedents i els requeriments mecànics; i els d’Enginyeria de Materials (UB) fan la selecció de materials per al nou disseny. En el present projecte finançat pel PMID s’han incorporat els alumnes de la Universitat Politècnica de Catalunya (UPC), treballant la part de processat i obtenció del prototip. A més, el projecte actual pretén portar a terme un servei a la comunitat (ApS). Es va contactar amb el Maset de Frater, un centre especialitzat en persones amb limitacions funcionals severes ubicat al Grao de Castelló. El centre i, concretament els interns i el gabinet tècnic del centre, han actuat com a ens promotor i usuari final del producte objecte del treball durant els dos cursos que ha durat el projecte. En aquest sentit, els estudiants de les universitats participants han tingut la possibilitat de contactar i interactuar amb l’usuari final amb la finalitat de conèixer les seves limitacions i restriccions, de manera que el seu treball s’ha vist clarament reforçat de manera positiva.2016PID-UB/00

Novel shape-stabilized phase change material with cascade character: synthesis, performance and shaping evaluation

Thermal Energy Storage (TES) materials, such as Phase Change Materials (PCMs) are proven to enhance the energy efficiency in many fields, such as automotive and building sectors, which correspond to the most energy intensive ones. Shape-stabilized PCM and cascade PCM are procedures to overcome the most important barriers when PCMs are applied since PCMs need to be encapsulated for their technical use: the leakage of the liquid phase, corrosion, low heat transfer and narrow temperature of application. In the present study, a novel shape stabilized PCM with cascade performance (cascade shape stabilized phase change material, CSS-PCM) is synthesized via dissolution, which allows up to 60 wt.% of a paraffin-PCM in the final composition. The novel CSS-PCM is based on a biopolymer, the polycaprolactone (PCL), a low melting temperature polyester as polymeric matrix and RT27 and Micronal DS 5040 acting as PCM. To evaluate the performance of the new TES materials developed, several techniques have been used: Differential Scanning Calorimetry (DSC), and Fourier-Transformed Infrared (FT-IR) spectroscopy were used to evaluate the thermophysical properties and the chemical properties of the different formulations. The CSS-PCM show an increment of storage capacity by increasing the PCM content, and the thermal reliability was also tested: some of the CSS-PCM formulations were stable for up to 500 thermal cycles. Finally, as a potential application of the new polymeric-based PCM 3D, a printing attempt was performed in order to analyze the viability of the formulations to be used as 3D printing material as a first proof of concept

Flexible Hybrid Circuit Fully Inkjet-Printed: Surface Mount Devices Assembled by Silver Nanoparticles-Based Inkjet Ink

Nowadays, inkjet-printed devices such as transistors are still unstable in air and have poor performances. Moreover, the present electronics applications require a high degree of reliability and quality of their properties. In order to accomplish these application requirements, hybrid electronics is fulfilled by combining the advantages of the printing technologies with the surface-mount technology. In this work, silver nanoparticle-based inkjet ink (AgNP ink) is used as a novel approach to connect surface-mount devices (SMDs) onto inkjet-printed pads, conducted by inkjet printing technology. Excellent quality AgNP ink-junctions are ensured with high resolution picoliter drop jetting at low temperature (∼150 °C). Electrical, mechanical, and morphological characterizations are carried out to assess the performance of the AgNP ink junction. Moreover, AgNP ink is compared with common benchmark materials (i.e., silver epoxy and solder). Electrical contact resistance characterization shows a similar performance between the AgNP ink and the usual ones. Mechanical characterization shows comparable shear strength for AgNP ink and silver epoxy, and both present higher adhesion than solder. Morphological inspections by field-emission scanning electron microscopy confirm a high quality interface of the silver nanoparticle interconnection. Finally, a flexible hybrid circuit on paper controlled by an Arduino board is manufactured, demonstrating the viability and scalability of the AgNP ink assembling technique

A study of carbon nanofibers and active carbon as symmetric supercapacitor in aqueous electrolyte: a comparative study

Symmetric supercapacitors are fabricated by carbon nanofibers (CNF) and activated carbon (AC) using similar proportions of 7 wt% polyvinylidene fluoride (PVDF) polymer binder in an aqueous electrolyte. In this study, a comparison of porous texture and electrochemical performances between CNFs and AC based supercapacitors was carried out. Electrodes were assembled in the cell without a current collector. The prepared electrodes of CNFs and AC present Brunauer-Emmett-Teller (BET) surface area of 83 and 1042 m2/g, respectively. The dominant pore structure for CNFs is mesoporous while for AC is micropore. The results showed that AC provided higher specific capacitance retention up to very fast scan rate of 500 mV/s. AC carbon had a specific capacitance of 334 F/g, and CNFs had 52 F/g at scan rate 5 mV/s in aqueous solution. Also, the results indicate the superior conductivity of CNFs in contrast to AC counterparts. The measured equivalent series resistance (ESR) showed a very small value for CNFs (0.28 Ω) in comparison to AC that has an ESR resistance of (3.72 Ω). Moreover, CNF delivered higher specific power (1860 W/kg) than that for AC (450 W/kg). On the other hand, AC gave higher specific energy (18.1 Wh/kg) than that for CNFs (2 Wh/kg).This indicates that the AC is good for energy applications. Whereas, CNF is good for power application. Indeed, the higher surface area will lead to higher specific capacitance and hence higher energy density for AC. For CNF, lower ESR is responsible for having higher power density

Study of mixing process of low temperature co-fired ceramics photocurable suspension for digital light processing stereolithography

The Low Temperature Co-fired Ceramic (LTCC) materials are highly used for high frequency devices required for high-speed data communications, representing an attractive material for electronic applications with a direct industrial applicability. The development of a photocurable LTCC suspension for Digital Light Processing Stereolithography (DLP-SLA) technology is presented in this work. The LTCC suspension, with an optimal solid load of 40.4 vol%, was characterized along its preparation regarding the rheological behaviour, dispersant content, particle size distribution in function of milling time and photocuring properties in a visible light range. The effect of the particle size change, through ball milling, on viscosity and photocuring behaviour was studied, achieving an optimal mixing range time, which highlights the importance of the manufacturing standardization of the photocurable suspensions. The optimized suspension presents a viscosity of 3.6 Pa s at shear rate of 2 s−1, a sensitivity of 41 μm and a critical energy dose of 15 mJ cm−2. The printing process was successfully achieved, demonstrated by some defect-free printed pieces

Epitaxial growth of SrTiO3 films on cube-textured Cu-clad substrates by PLD at low temperature under reducing atmosphere

The growth of epitaxial {001} SrTiO3 (STO) on low-cost cube-textured Cu-based clad substrate at low temperature was carried out by means of pulsed laser deposition (PLD). STO film was deposited in one step under a reducing atmosphere (5% H2 and 95% Ar mixture) to prevent the oxidation of the metal surface. The optimization of PLD parameters leads to a sharpest biaxial texture at a temperature as low as 500 °C and a thickness of 500 nm with a (100) STO layer. The upper limit of highly textured STO thickness was also investigated. The maximum thickness which retains the best quality {001} texture is 800 nm, since the texture is preserved not only through the layer but also on the surface. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) measurements showed that STO films are continuous, dense, and smooth with very low roughness (between 5 and 7 nm). This paper describes the development of STO layer by means of PLD in absence of oxygen throughout the process, suggesting an alternative and effective method for growing highly {001} textured STO layer on low-cost metal substrates

NO2 Measurements with RGB Sensors for Easy In-Field Test

We present a simple an inexpensive method to implement a Griess-Saltzman-type reaction that combines the advantages of the liquid phase method (high specificity, fast response time) with the benefits of a solid implementation (easy to handle). We demonstrate that the measurements can be carried out using conventional RGB sensors; circumventing all the limitations around the measurement of the samples with spectrometers. We also present a method to optimize the measurement protocol and target a specific range of NO2 concentrations. We demonstrate that it is possible to measure the concentration of NO2 from 50 ppb to 300 ppm with high specificity and without modifying the sensing elements

Highly Specific and Wide Range NO2 sensor with color readout

We present a simple and inexpensive method to implement a Griess-Saltzman-type reaction that combines the advantages of the liquid phase method (high specificity and fast response time) with the benefits of a solid implementation (easy to handle). We demonstrate that the measurements can be carried out using conventional RGB sensors; circumventing all the limitations around the measurement of the samples with spectrometers. We also present a method to optimize the measurement protocol and target a specific range of NO2 concentrations. We demonstrate that it is possible to measure the concentration of NO2 from 50 ppb to 300 ppm with high specificity and without modifying the Griess-Saltzman reagent

Oxide wizard: an EELS application to characterize the white lines of transition metal edges

Physicochemical properties of transition metal oxides are directly determined by the oxidation state of the metallic cations. To address the increasing need to accurately evaluate the oxidation states of transition metal oxide systems at the nanoscale, here we present Oxide Wizard. This script for Digital Micrograph characterizes the energy-loss near-edge structure and the position of the transition metal edges in the electron energy-loss spectrum. These characteristics of the edges can be linked to the oxidation states of transition metals with high spatial resolution. The power of the script is demonstrated by mapping manganese oxidation states in Fe3O4/Mn3O4 core/shell nanoparticles with sub-nanometer resolution in real spac