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    Desenvolvimento de procedimento para análise química de alumina combinando fusão e espectrometria de fluorescência de raios x
    (Universidade Federal de São Carlos, 2026-08-25)
    Carvalho, Larissa Brenda
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    Nóbrega, Joaquim de Araújo
    ;
    http://lattes.cnpq.br/8833989058164529
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    https://orcid.org/0000-0001-9134-9547
    ;
    https://lattes.cnpq.br/2348829608819033
    Alumina, or aluminum oxide, is a refractory material with excellent mechanical properties and is the primary raw material for the production of metallic aluminum (Smelter Grade Alumina—SGA). To ensure the purity of alumina, monitoring the levels of contaminants such as CaO, Fe2O3, SiO2 and Na2O is essential and is carried out by determining its chemical composition, typically using X-ray fluorescence spectrometry (XRF). At Companhia Brasileira de Alumínio (CBA), the traditional method for preparing alumina samples involves pulverization followed by pressing, with subsequent analysis by XRF. Although well-established, this method has disadvantages, such as sample heterogeneity, matrix effects, contamination, and ergonomic risks to analysts. This professional master’s project focused on developing a method for preparing alumina samples via fusion, followed by XRF measurements. Fusion offers advantages such as more homogeneous samples, reduced matrix effects, greater safety for analysts, and shorter preparation times. However, it presents challenges, such as sample dilution in the flux, which can reduce the sensitivity of certain elements and affect the accuracy of the results. Sample preparation is crucial for ensuring the accuracy of analytical results, and both pulverization followed by pressing and fusion are relevant strategies for preparing samples for XRF. Choosing the most appropriate method is essential for optimizing resources, ensuring analyst safety, and guaranteeing the reliability of results, in accordance with safe practices. For the fusion method, we used a 2-g sample of aluminum oxide and 10 g of flux containing 49.5% m/m lithium tetraborate, 49.5% m/m lithium metaborate, and 1% m/m lithium bromide. The mixture was transferred to a 95%-5% Pt-Au crucible and subjected to a heating program with a maximum temperature of 1050 °C and a total duration of 13.5 min. After fusion, the solution is poured into a mold to form the glass pellet. The entire procedure is performed mechanically using a fusion apparatus (Katanax, Model K2 Prime). The finished glass pellet is analyzed by WDXRF. Instrumental measurements using the glass pellet were conducted according to the strategy adopted for the pressed pellet. The concentrations determined for the main contaminants i.e., CaO, Fe₂O₃, Na₂O, and SiO₂ fall within the process specification range for quality control. The analytical procedure developed was evaluated using both qualitative and quantitative approaches. The qualitative approach proved suitable for rapid process control. On the other hand, the quantitative approach was effective, and its accuracy was demonstrated by comparing the results obtained by fusion and by grinding-pressing. Validation parameters were also investigated. The linearity of the analytical curves for CaO, Fe₂O₃, Na₂O, and SiO₂ was adequate according to the statistical parameters evaluated, such as homoscedasticity, residuals, and correlation and determination coefficients. The detection limits (LDs) and quantification limits (LQs) were determined, and low sensitivity was observed for Na₂O. Precision was evaluated using the repeatability parameter in the CRM samples. In this study, the concentration range of the fusion procedure was evaluated from 100 to 1000 mg/kg applying tablet dilution tests, by optimizing the masses of the flux and the sample. Trueness was determined using two certified reference materials.
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    Estudo e alterações de composição e processos para a otimização da distribuição de tamanho de carbonetos do aço M3:2
    (Universidade Federal de São Carlos, 2025-08-27)
    Morandi, Pedro Olmos
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    Bolfarini, Claudemiro
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    http://lattes.cnpq.br/9231627080617037
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    https://orcid.org/0000-0002-3099-3694
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    Otani, Lucas Barcelos
    The VIMAC3V steel, which is a variation of the High-Speed Steel M3:2 according to ASTM A600, belongs to the category of high molybdenum content High-Speed Steels (M class) and includes alloying elements such as chromium, vanadium, and tungsten. It stands out for its exceptional wear resistance combined with toughness and hot hardness, making it suitable for various industrial tools such as taps, reamers, knives, dies, and punches. However, due to the high number of precipitated carbides in the matrix, VIMAC3V steel exhibits high resistance to abrasive wear during the machining of the final tool, resulting in low grindability when compared to other steels in the same class. This limitation has the potential to negatively impact productivity and increase industrial costs. Thus, this study was divided into two parts. The first part involved the characterization of commercial steels from different suppliers. The objective of this phase was to correlate the microstructure with the best combinations of properties for the application of this material. The results obtained from the characterization of commercial steels showed finer and more homogeneously distributed carbides, as well as relevant changes in the chemical composition of the material. The second phase consisted of implementing changes in the manufacturing process of this material to obtain an optimized microstructure based on the results obtained in the first phase. The studies focused on chemical composition analysis, microstructure, carbide quantification, types of inclusions, and wear resistance. The main microstructural feature observed was the distribution of the present carbides which demonstrated a significant improvement in the distribution and size of carbides. Therefore, it was concluded that the applied changes were effective and provided insights to understand and propose improvements in the microstructure toward refined carbides.
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    Estudo dos mecanismos de trincamento em agregado de magnésia-cromo eletrofundido e alternativas sem Cr
    (Universidade Federal de São Carlos, 2025-03-06)
    Ribeiro, Gabriela Bugni
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    Pandolfelli, Victor Carlos
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    http://lattes.cnpq.br/7369376873984839
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    Coury, Francisco Gil
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    http://lattes.cnpq.br/8609825406277730
    There is a need in the metallurgical industry for refractory materials with good physical and chemical properties. In this context, magnesia-chrome ceramics, composed of magnesium oxide (MgO) and chromium oxide (Cr₂O₃), emerged as an efficient solution for various applications starting in the 1960s, due to their good resistance to corrosion and thermal shock damage. However, there is a growing concern regarding the use of these refractories due to the release of hexavalent chromium, a toxic and carcinogenic compound for humans. In this study, the microstructures of electrofused magnesia-chrome aggregate (EMCA) and two alternative compositions (Composition 1 and Composition 3) – containing iron oxide and magnesium oxide – were investigated, focusing on crack formation and their associated mechanisms. Experimental results indicate that the sequence of materials with the highest occurrence of cracks is: EMCA > Composition 3 > Composition 1. This behavior suggests that the variation in lattice parameters between the phases has a greater influence on crack nucleation than the difference in thermal expansion coefficients. A smaller critical radius for the interface to become incoherent generates higher stresses in the matrix, promoting a greater accumulation of dislocations and, consequently, the occurrence of the Zener Stroh mechanism. Thus, this study contributes to the understanding of the factors affecting thermal shock resistance in these materials, providing a foundation for the development of more efficient and sustainable refractory solutions.
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    Ondas de ódio: o deslocamento de contradições materiais para o gênero no discurso da extrema-direita digital brasileira
    (Universidade Federal de São Carlos, 2026-09-03)
    Mazzon Camargo, Maysa
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    Leite, Kelen Christina
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    http://lattes.cnpq.br/0993995005511082
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    https://orcid.org/0000-0002-8590-1857
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    https://lattes.cnpq.br/5336595963732305
    This study analyzes how gender-targeted hate speech from the Brazilian digital far right displaces material contradictions onto moral and identity-based terrain, turning gender into the privileged axis of antagonism. It examines three instances of discursive circulation, with varying degrees of regulation and visibility, treated as simultaneous rather than successive. Experimentation takes place in anonymous forums, mediation on mainstream platforms, and transnational moral legitimation in think tanks and political networks. The theoretical framework articulates Discourse Analysis (Pêcheux and Courtine) and Paveau’s technodiscursive approach with the contributions of Davis, Fraser, Brown, and Butler. In the experimentation instance, posts from Brazilian IPs on 4chan between 2013 and 2024 were examined through log-likelihood significance analysis (G²; Dunning) and topic modeling with BERTopic (Grootendorst), followed by close reading of discursive sequences. The articulation between digital methods and Discourse Analysis makes it possible to move from large-scale archives to analyzable selections without forgoing the reading of discursive materiality. In the mediation instance, the corpus comprises posts from two X/Twitter profiles, collected with Zeeschuimer and organized in 4CAT. In the legitimation instance, public documents from the Instituto Conservador-Liberal and the Political Network for Values were examined, along with a speech delivered at one of the latter’s transnational events. Across all three instances, the analysis found the same operation: a material loss is stated with precision and, in the same gesture, blamed on women. No path of formulations was observed between the instances. What connects them is the statement of a natural division of roles between the sexes, which appears as transverse discourse in the forum and on social media and as a principle in institutional documents; the transit occurs through actors, not through formulations. The study concludes that gender functions as a mechanism for concealing material conflict, in an operation that recurs irregularly and multidirectionally across the instances.
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    Práticas de apoio e acompanhamento da gestão pedagógica às professoras iniciantes da educação infantil: um balanço bibliográfico de pesquisas na área nos últimos 30 anos
    (Universidade Federal de São Carlos, 2026-08-20)
    Pereira, Stephanie Gonçalves
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    Onofre, Marcia Regina
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    http://lattes.cnpq.br/7176529351192598
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    http://www.researcherid.com/rid/D-8233-2014
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    http://lattes.cnpq.br/9840185362964726
    The beginning of a teaching career is a distinctive phase in teachers’ professional trajectories, marked by a range of feelings, experiences, challenges, and discoveries. In this regard, we believe that the analysis of studies addressing this period can broaden discussions on the subject and strengthen the movement toward teacher professionalization in Brazil, particularly through the theoretical perspective of the Epistemology of Practice (Schön, 1992; Marcelo Garcia, 1999, 2010; Tardif, 2002, 2013, 2014; Nóvoa, 2017, 2019; Onofre, 2025). The aim of this research was to examine doctoral dissertations and master’s theses produced in Brazil over the last 30 years (1995–2025), seeking to identify and analyze the support and guidance practices provided by pedagogical management to early-career female teachers in Early Childhood Education. The study was based on the hypothesis that such support and guidance practices are essential to assisting these teachers in the initial stages of their careers. In this context, the following research question was established: What support and guidance practices does pedagogical management provide to early-career female teachers in Early Childhood Education, according to a bibliographic review of research produced over the last 30 years (1995–2025)? To address this question, a qualitative, exploratory, and bibliographic study was conducted, drawing on Gil (2002). Research available in the Brazilian Digital Library of Theses and Dissertations (BDTD) was surveyed to develop a bibliographic overview of scientific publications produced between 1995 and 2025. Based on the established selection criteria, 12 studies were selected, comprising four doctoral dissertations and eight master’s theses, which were examined and analyzed throughout the study. Based on this mapping, the research sought to systematize educational proposals and support and guidance practices for early-career female teachers that had yielded positive results, contributing to reflection on professional pathways in teaching and to the strengthening of such practices. The analysis identified three thematic categories: (1) early-career female teachers; (2) pedagogical management; and (3) support from more experienced peers. The findings revealed support and guidance practices organized into seven dimensions: (1) a collective culture of welcoming and active listening; (2) systematic pedagogical and emotional support provided by school management, including pedagogical coordinators and school principals; (3) the direct involvement of experienced peers as mentors; (4) continuing professional development centered on the school environment, through face-to-face formats, such as HTPCs, HTPIs, and PEAs, or online formats, such as the Moodle-based program PFoM; (5) support, guidance, and continuing professional development initiatives developed through university–school partnerships; (6) written and narrative documentation tools, as well as practical strategies that foster empowerment and reflection-in-action; and (7) personalized welcoming practices for teachers upon their arrival at educational institutions. Based on the identification of these practices, a professional development proposal was developed to outline pathways for collaboration between pedagogical coordinators and more experienced peers, structured as a continuum of professional development. The findings are expected to contribute to Early Childhood Education systems by providing insights to inform the development and strengthening of policies and practices aimed at supporting and guiding early-career female teachers.