Prática de ensino supervisionada em educação pré-escolar e ensino do 1.º ciclo do ensino básico

O presente relatório final de estágio foi desenvolvido no âmbito da Prática de Ensino Supervisionada do curso de Mestrado em Educação Pré-escolar e do 1º Ciclo do Ensino Básico e pretende descrever, refletir e fundamentar algumas das intervenções pedagógicas desenvolvidas em contexto Pré-escolar e 1º Ciclo do Ensino Básico, decorridas numa Instituição Particular de Solidariedade Social e numa escola de rede pública, respetivamente. No decorrer da ação educativa tentamos apoiar a iniciativa e motivação das crianças, para que elas fossem co construtoras de saberes, assumindo-nos como observadores, apoiantes e estimuladores das suas ações. Da observação emergiu a tomada de decisões ao nível de novas propostas educacionais, uma vez que procuramos conciliar as áreas de conteúdo e curriculares com os interesses e necessidades do grupo de crianças. Relativamente à organização, este relatório encontra-se dividido em três grandes capítulos, sendo o primeiro relativo à contextualização das instituições onde foram desenvolvidas as intervenções pedagógicas bem como do grupo de crianças; o segundo capítulo abarca um conjunto de reflexões e análises referentes à organização do espaço, do tempo, das interações bem como as experiências de aprendizagem desenvolvidas em ambos os contextos. Por último, no terceiro capítulo é realizada uma reflexão global acerca das construções por nós efetuadas enquanto futuros educadores/professores. Destaca-se a importância desta etapa formativa na construção de competências cognitivas e relacionais para o desenvolvimento pessoal e profissional, do futuro educador/professor. This final report stage was developed under the Supervised Teaching Practice of the Master of early childhood and primary school education and aims to describe, reflect and support some of the pedagogical interventions developed in the context early childhood education and primary school, elapsed in a private Institution of Social Solidarity and a public school, respectively.During the educational tried to support the initiative and motivation of children, that they were co construction of knowledge, taking us as observers, supporters and promoters of their actions. Observation emerged the decision making level of educational proposals, since they seek to reconcile the curricular content areas and with the interests and needs of the group of children.For the organization, this report is divided into three main chapters, the first on the context of the institutions where they were developed educational interventions as well as the group of children, the second chapter comprises a collection of reflections and analyzes concerning the organization of space, time, interactions and learning experiences developed in both contexts.Finally, the third chapter is held a comprehensive discussion about the constructions made by us as future educators / teachers. We emphasize the importance of this formative stage in the construction of cognitive and relational skills for personal and professional development, the future educator / teacher

Deposition of Super-Hydrophobic Silver Film on Copper Substrate and Evaluation of Its Corrosion Properties

A simple and versatile chemical solution deposition process is reported to manipulate the wettability properties of copper sheets. The whole process has the advantage of being time-saving low cost and environment-friendly. An adherent silver coating was achieved under optimal conditions. Scanning electron microscopy and X-ray diffraction were used to examine the silver film structure. A confocal microscope was used to record the 3D topography and assess the film roughness of the surface. A dual morphology was revealed, consisting of broad regions with feather-like structured morphologies and some areas with spherical morphologies. Such silver-coated copper samples exhibited a sufficiently stable coating with superhydrophobicity, having a maximum water contact angle of 152°, along with an oleophilic nature. The corrosion behavior of the produced hydrophobic copper under optimal conditions was evaluated by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) using a 3.5% NaCl solution. The corrosion protection mechanism was elucidated by the proposed equivalent circuits, indicating that the superhydrophobic silver coating acted as an effective barrier, separating the Cu substrate from the corrosive solution. The superhydrophobic coating demonstrated enhanced anti-corrosion properties against NaCl aqueous solution in relation to the copper substrate as indicated from both EIS and potentiodynamic polarization experiments

Corrosion Behavior of Stainless Steels in CO2 Absorption Process Using Aqueous Solution of Monoethanolamine (MEA)

The corrosion behavior of two stainless steels (316L and 304L) was evaluated using a CO2-loaded aqueous solution of 30 wt.% monoethanolamine (MEA) with a view to simulating corrosion related mechanisms in amine treatment procedures. Corrosion behavior was experimentally evaluated as a function of CO2 loading and solution temperature, using electrochemical techniques (polarization curves, cyclic polarization, and EIS measurement). The results reveal that the aqueous MEA solution containing CO2 creates a favorable environment for the corrosion of both stainless steels. The rate of corrosion is accelerated when the temperature of the loaded MEA solution rises, which was attributed to the thermal degradation of the loaded MEA, thus causing higher kinetics of the cathodic reactions at higher temperatures. More specifically, for the SS 304L the corrosion rate is almost doubled when the solution temperature is increased from 25 °C to 40 °C and is quadrupled when the solution temperature rises to 80 °C. For the SS 316L, the corrosion rate becomes almost threefold and sixfold upon increasing temperature of the load amine solution to 40 °C and 80 °C, respectively. The overall corrosion rate of SS 316L is lower with respect to the SS 304L for the same temperature and loading conditions. The essential dependency of corrosion rate on solution type (unloaded and loaded MEA solution) demonstrates that the corrosion process and reactions are controlled by a diffusion mechanism

Production of porous materials and evaluation of their properties

The aim of the present study is to introduce a cost-effective and environmentally friendly production process of open-cell metal foams with a view to manufacture porous materials exhibiting good morphological and structural homogeneity. The work also focuses on optimizing the production process control to produce higher quality materials and to achieve a better reproducibility and predictability of their properties. A space-holder method using crystalline raw cane sugar, as a novel leachable pattern for manufacturing open-cell metal foams is described. The mechanical behavior of the produced Al-foams as well as the deformation mechanisms developed during mechanical testing are investigated experimentally and analytically through a developed Finite Element Method simulation of compression tests using the real porous geometry, obtained via computed tomography. Additionally, the feasibility for carburized foam production in an one step-process using crystalline raw cane sugar and employing the proposed porous production methodology is investigated, whilst the effect of carburisation on the mechanical and anti-corrosive properties of the produced carburized foams is assessed. A low-vacuum furnace was used for the production process of the porous metals. In order to evaluate the effect of sintering atmosphere on the produced foams and to achieve an effective carburization process a high-vacuum apparatus was constructed. The micro and macro-structure of the produced foams are examined through optical and scanning electron microscopy whereas XRD measurements were used to evaluate the crystal structures and phases produced. Static-compression tests were conducted to assess the influence of morphological and production parameters on the mechanical behaviour of the produced foams. A X-ray tomography apparatus with a 5 μm focal spot reflection target X-ray tube source working in the absorption mode, was used to acquire the 3D images of the foam samples necessary for the creation of the FEM-based foam model and for the 3D characterization of the porous products. The thermal analysis via ΤG-DTA measurements was applied on the raw cane sugar to deduce its decomposition temperature. The electrochemical behavior of the Al-foam and carburized Al-foam was monitored by polarization measurements. The proposed method is attractive and environmentally friendly, given that it does not lead to any dangerous by-products or emissions and does not employ any toxic, flammable or explosive material. As an additional benefit, the proposed method is capable of producing low-cost, net-shape metal foams with tailored distribution of pore size or relative density presenting excellent reproducibility and predictability of their properties. The advantages of crystalline raw cane sugar as a novel space-holder are that is chemically stable in contact with the parent metal material and can be easily removed from the green product prior to sintering, Also it is cheap, easy to purchase in the market and does not corrode the foam material. The FEM modeling of the compressive properties of the real foam geometry leads not only to an in-depth understanding of the deformation mechanisms developed but also gives insight to the structure-properties correlation, facilitating thus the final design of the foam material. The feasibility for carburized foam production in an one step-process using crystalline raw cane sugar is among the important advantages of the proposed porous production methodology. The considerable control of carburization process conducted at relatively low temperature (400 oC) leads to an homogeneous distributed carbon layer around each pore enhancing thus the corrosion behaviour of the carburized porous materials.Σκοπός της παρούσας εργασίας είναι η ανάπτυξη και βελτιστοποίηση διαδικασίας παραγωγής αφρών με οικονομική και περιβαλλοντικά φιλική μέθοδο ώστε οι παραγόμενοι μεταλλικοί αφροί να εμφανίζουν μεγάλη ομοιογένεια στο μέγεθος των πόρων και αυξημένη ομοιομορφία στην κατανομή τους εντός του μητρικού υλικού, χαρακτηριστικά τα οποία προσδίδουν σημαντική βελτίωση αλλά και επαναληψιμότητα στις ιδιότητες του τελικού πορώδους προϊόντος. Για την επίτευξη του παραπάνω στόχου, χρησιμοποιήθηκε η διαδικασία υδατοδιάλυσης-πυροσυσσωμάτωσης για την παραγωγή μεταλλικών αφρών αλουμινίου χρησιμοποιώντας ως καινοτόμο πληρωτικό μέσο κρυσταλλική ακατέργαστη καστανή ζάχαρη. Επιπροσθέτως διερευνάται, τόσο πειραματικά όσο και αναλυτικά με Μεθόδους Πεπερασμένων Στοιχείων (FEM), η μηχανική συμπεριφορά και οι μηχανισμοί παραμόρφωσης των κελιών των παραγόμενων αφρών υπό θλιπτικά φορτία. Στα πλαίσια της παρούσας εργασίας εξετάζεται η δυνατότητα ταυτόχρονης ενανθράκωσης και παραγωγής πορώδους αλουμινίου χρησιμοποιώντας την καστανή ζάχαρη ως πληρωτικό αλλά και ενανθρωτικό μέσο και θα αξιολογηθεί επίσης η επίδραση της ενανθράκωσης στη μηχανική και διαβρωτική συμπεριφορά του πορώδους αλουμινίου. Για την παραγωγή πορωδών μεταλλικών υλικών χρησιμοποιήθηκε φούρνος χαμηλού κενού ενώ για την αξιολόγηση της επίδρασης της ατμόσφαιρας πυροσυσσωμάτωσης αλλά και την διεξαγωγή της ενανθράκωσης των πορωδών μεταλλικών υλικών συναρμολογήθηκε διάταξη υψηλού ή μέσου κενού. Για τη διερεύνηση των μορφολογικών παραμέτρων των παραγομένων αφρών χρησιμοποιήθηκε οπτική και σαρωτική ηλεκτρονική μικροσκοπία (SEM) ενώ οι κρυσταλλικές φάσεις που αναπτύχθηκαν μελετήθηκαν με περίθλαση ακτίνων-Χ (XRD). Η δημιουργία της τρισδιάστατης γεωμετρίας των πορωδών υλικών, η οποία είναι απαραίτητη για τη διεξαγωγή FEM προσομοιώσεων αλλά και για το τρισδιάστατο χαρακτηρισμό των πορωδών υλικών, επιτεύχθηκε με χρήση αξονικού τομογράφου ακτίνων-Χ. Τα θερμικά χαρακτηριστικά της καστανής ζάχαρης μελετήθηκαν μέσω θερμοβαρυτικής ανάλυσης και διαφορικής θερμικής ανάλυσης. (ΤG-DTA) ενώ η διαβρωτική συμπεριφορά των αφρών αξιολογήθηκε μέσω ηλεκτροχημικής διάβρωσης. Η βελτιστοποίηση της παραγωγικής μεθόδου των αφρών με την τεχνική κονιομεταλλουργίας στοχεύει κυρίως στον καλύτερο έλεγχο της διαδικασίας για την παραγωγή υψηλής ποιότητας αφρών ανοικτού κελιού με στόχο την επαναληψιμότητα και την προβλεψιμότητα των ιδιοτήτων των παραγόμενων αφρών. Η κρυσταλλική καστανή ζάχαρη η οποία χρησιμοποιήθηκε ως υδατοδιαλυτό πληρωτικό μέσο είναι φθηνή, χημικά σταθερή σε επαφή με το μητρικό και δεν διαβρώνει τον μεταλλικό υλικό του αφρού. Η μέθοδος είναι ελκυστική και περιβαλλοντικά φιλική δεδομένου ότι δεν οδηγεί σε επικίνδυνα παραπροϊόντα ή εκπομπές και δεν απαιτεί την εφαρμογή τοξικών, εύφλεκτων ή εκρηκτικών υλικών σε κανένα στάδιο της παραγωγικής διαδικασίας. H προσομοίωση των μηχανικών ιδιοτήτων της πραγματικής τρισδιάστατης γεωμετρίας του αφρού συμβάλλει σημαντικά στην κατανόηση των μηχανισμών παραμόρφωσης αλλά και στη θέσπιση συσχέτισης μεταξύ της δομής και των μηχανικών ιδιοτήτων διευκολύνοντας τον τελικό σχεδιασμό και ανάπτυξη των αφρών. Επιπροσθέτως για πρώτη φορά επιτεύχθηκε διαδικασία ταυτόχρονης ενανθράκωσης και παραγωγής πορωδών υλικών σε ένα παραγωγικό στάδιο με τη χρήση της κρυσταλλικής ακατέργαστης καστανής ζάχαρης ως πληρωτικό και ενανθρακωτικό μέσο. Το παραγόμενο ενανθρακωμένο πορώδες προϊόν εμφανίζει ομοιόμορφο στρώμα άνθρακα στην εξωτερική επιφάνεια αλλά και στους εσωτερικούς πόρους βελτιώνοντας τη διαβρωτική συμπεριφορά του. Πλεονεκτήματα της μεθόδου είναι ο σημαντικός έλεγχος της διαδικασίας ενανθράκωσης, η οποία επιτυγχάνεται σε χαμηλές θερμοκρασίες (400 οC)

Growth of hydrophobic membrane on copper surface and study of its corrosive behavior

Hydrophobic films were produced on a copper surface by chemical methods. The whole process consisted of three stages. Initially the hierarchical structure of the surface was achieved by in situ reduction of Ag+ ions to Ag using silver nitrate solution, thereby creating a nanostructured surface. The copper surface was then coated with polydopamine by a simple immersion procedure. Finally, it was decorated with thiols, to achieve a hydrophobic surface. The wetting angle was used to evaluate the hydrophobicity of the produced surfaces. The anti-corrosion behavior of the produced hydrophobic films, were evaluated on the specimens that showed higher hydrophobicity by electrochemical methods. Electrochemical techniques (potentiodynamic polarization and resistance spectroscopy tests) were performed in 3.5% NaCl solution. Morphology was investigated by scanning electron microscopy (SEM). All experimental results showed a clear improvement in the corrosion behavior of the hydrophobic copper surfaces while the hydrophobicity was maintained after the corrosion tests

Improvement of the Interfacial Fatigue Strength and Milling Behavior of Diamond Coated Tools via Appropriate Annealing

This article deals with the potential to reduce the amount of the residual stresses in the diamond films on cemented carbide inserts for improving their effective interfacial fatigue strength and thus their wear resistance. In this context, nano-crystalline diamond coatings (NCD) were deposited on cemented carbide inserts. A portion of these coated tools were annealed in vacuum for decreasing the amount of residual stresses in the film structure. The annealing temperature was appropriately selected for keeping the substrate strength properties invariable after the coating annealing. Inclined impact tests at ambient temperature on the untreated and heat-treated diamond coated tools were conducted for evaluating their effective interfacial fatigue strength. Depending upon the impact load, after a certain number of impacts, damages in the film-substrate interface develop, resulting in coating detachment and lifting. Via appropriate FEM (Finite Element Method)-evaluation of the impact imprints, the residual stresses in the diamond film structure were determined. Milling experiments were conducted for evaluating the cutting performance of the coated tools using aluminum foam as workpiece material. A correlation between the interfacial fatigue strength of diamond coatings and their residual stresses affected by annealings contributed to the explanation of the attained cutting results

Effect of the crystallinity of NCD and MLD diamond coatings characterized by same level of residual stresses after annealing on their fatigue strength and wear behavior in milling

Nano-composite (NCD) and multi-layered (MLD) diamond coatings were deposited on cemented carbide tools using hot filament chemical vapour deposition (HFCVD) techniques. Appropriate annealings were conducted on the examined diamond coatings in order to be characterized by the same level of residual stresses. The crystalline structure of the employed diamond coatings was investigated by conducting Raman spectra. Inclined impact tests at ambient and elevated temperatures were carried out for assessing their temperature-dependent fatigue strength. Moreover, the wear behaviour of diamond coated inserts was investigating in milling aluminum foam. Raman spectra were also conducted on the treated diamond coatings for capturing potential crystalline changes developed due to the exercised thermal and dynamic mechanical loads during cutting. According to the attained results, the coexistence of sp2– and sp3-bonded phases in the cases of MLD diamond coatings results in an accelerated wear development, despite their structure capability to decelerate the crack propagation. As a result, nano-crystalline diamond coatings characterized only by sp3-bonded phase exhibit an improved wear behaviour. The cutting performance of the NCD coated inserts is further improved due to the enhanced tribological properties of the NCD coatings

Growth of hydrophobic membrane on copper surface and study of its corrosive behavior

Hydrophobic films were produced on a copper surface by chemical methods. The whole process consisted of three stages. Initially the hierarchical structure of the surface was achieved by in situ reduction of Ag+ ions to Ag using silver nitrate solution, thereby creating a nanostructured surface. The copper surface was then coated with polydopamine by a simple immersion procedure. Finally, it was decorated with thiols, to achieve a hydrophobic surface. The wetting angle was used to evaluate the hydrophobicity of the produced surfaces. The anti-corrosion behavior of the produced hydrophobic films, were evaluated on the specimens that showed higher hydrophobicity by electrochemical methods. Electrochemical techniques (potentiodynamic polarization and resistance spectroscopy tests) were performed in 3.5% NaCl solution. Morphology was investigated by scanning electron microscopy (SEM). All experimental results showed a clear improvement in the corrosion behavior of the hydrophobic copper surfaces while the hydrophobicity was maintained after the corrosion tests

The footprint of surface modification treatments on the corrosion-fatigue of AA7075-T651

Different manufacturing and surface modification treatments distinctively affect the surface characteristics and microstructure of the workpiece, having a different impact on their effective life-span. The corrosion-fatigue behavior of as-machined (wire-EDM), blasted and anodized aluminum alloy 7075-T651 was investigated using 3.5wt% NaCl aqueous solution and distilled water as corrosive media. An in-situ corrosion-fatigue device capable of producing cyclic loads in a corrosive solution was employed, coupled with FEM analysis. Blasting process offered a prolongation of the corrosion-fatigue life-span in both corrosive media, when compared to the as-machined samples under identical conditions. Anodizing had a deleterious effect in all the examined cases

The footprint of surface modification treatments on the corrosion-fatigue of AA7075-T651

Different manufacturing and surface modification treatments distinctively affect the surface characteristics and microstructure of the workpiece, having a different impact on their effective life-span. The corrosion-fatigue behavior of as-machined (wire-EDM), blasted and anodized aluminum alloy 7075-T651 was investigated using 3.5wt% NaCl aqueous solution and distilled water as corrosive media. An in-situ corrosion-fatigue device capable of producing cyclic loads in a corrosive solution was employed, coupled with FEM analysis. Blasting process offered a prolongation of the corrosion-fatigue life-span in both corrosive media, when compared to the as-machined samples under identical conditions. Anodizing had a deleterious effect in all the examined cases