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Produção e caracterização de ligas do sistema Al-Co-Fe- Cr e aplicações como recobrimentos para barreiras térmicas
(Universidade Federal de São Carlos, 2015-07-23) Wolf, Witor; Botta Filho, Walter José; https://lattes.cnpq.br/8956458007749112; https://lattes.cnpq.br/9656544805116765
Since the discovery of the quasicrystalline alloys by D. Schechtamn in 1984, many research has been done in terms of coating application of these materials and their intermetallic approximants due to their physical and transport properties as: high hardness, low friction coefficient, low superficial adhesion energy, high oxidation resistance and low thermal conductivity. The low thermal conductivity combined with the thermal expansion in the same range of the usual metallic materials used as substrates in coatings make these alloys as potential substitutes for the traditional ceramics thermal barrier coatings. The alloy Al71Co13Fe8Cr8 has been studied in terms of thermal barrier applications. This alloy presents interesting properties and characteristics for this application. However, the information about this alloy on the literature is scarce and contradictory. In this sense, in the present work, the Al71Co13Fe8Cr8 alloy was selected for coating fabrication aiming to obtain a consistent structural characterization of this alloy. Results show that the Al71Co13Fe8Cr8 alloy is not a quasicrystalline forming composition. It is actually composed by two intermetallic phases, one hexagonal and the other monoclic, Al5Co2 and Al13Co4 respectively, which are approximant phases of the decagonal QC with the interesting physical and transport properties presented by the quasicrystalline phase. The coatings were also studied in terms of the interdifusion phenomena between the coating and a steel substrate at high temperatures. Alloys around the Al71Co13Fe8Cr8 compositional range were also fabricated in order to evaluate the phase formation on the aluminum rich region of the Al-Co-Fe-Cr system. Several intermetallic phases were observed, most of them quaternary extensions of Al-Co intermetallic phases. A quasicrystalline phase was also observed in one of the studied compositions.
Atividade orientadora de ensino de geometrias na perspectiva lógico-histórica : unidade entre ensino e aprendizagem na formação inicial de professores de matemática
(Universidade Federal de São Carlos, 2015-07-23) Santos, Talita Secorun dos; Sousa, Maria do Carmo de; https://lattes.cnpq.br/6637658562543505; https://lattes.cnpq.br/9052886361360320
The manner Teaching Activities (TAs) of different types of Geometry may be presented as a unity between teaching and learning, or rather, as Teaching Guiding Activity (TGA) in the initial formation of teachers, is discussed. It has thus been presumed that the logical and historical perspective may become a didactic factor in teachers´ initial formation when TAs are developed as from the subject-group-class-narrative dynamics. Current qualitative research was developed based on the following questions: Did teaching activities developed in the disciplines ‘Geometry’ and ‘Euclidian Geometry and Topic for Non-Euclidian Geometries’ generate aims and motives to teach and learn to teach Geometries? Did the activities experienced by the subject-group-class dynamics and posting of narratives become a TGA? Which are the productions of meanings, aims and motives explicit in the narratives prepared by undergraduates of the Math course during their experience in TAs of Geometries within the logical and historical perspective as from the subject-group-class dynamics? Data were retrieved from questionnaires, TAs, field diaries and narratives posted on the Internet. The empirical material was analyzed by four descriptive and analytic categories emerging from three-fold data, namely, From the isolated to the collective; The New; From Learning to Learning to Teach; Contradictions. Results show that Geometry TAs within the logical-historical perspective as from the subject-group-class-narrative dynamics trigger information related to the appropriation of theoretical knowledge, teaching of theoretical knowledge, organization of teaching, pedagogical activities and research in most people involved in the teaching-learning process.
Desenvolvimento de procedimento para determinação fotométrica de etanol em bebidas destiladas sem uso de reagentes explorando o efeito Schlieren
(Universidade Federal de São Carlos, 2015-07-23) Silva, Diogo Santos; Reis, Boaventura Freire dos; https://lattes.cnpq.br/7619359855870896; https://lattes.cnpq.br/6436952522509024
The knowledge and applications of Schlieren effect on the flow injection analysis process (FIA) showed that using the variation of refraction index, formed by concentration gradients during sample dispersion in carrier fluid is a practicable method for ethanol determination in distilled drinks. Based on this effect, we developed an analysis module that performs photometric measurements using flow cells of long optical path length. The method here proposed allowed the determination of ethanol without using reagents. Control of the devices, including solenoid valves and solenoid mini-pumps, was carried out by a microcontroller (Arduino Due) coupled to a microcomputer through serial interface. The control and data acquisition software was written using Visual Basic 6.0, C and C ++ languages. The flow analysis module developed for this study achieved an analytical frequency of 110 samples per hour, sample consumption of 400.2 μL and generation of 2.9 mL of effluent per determination.