Abstract This paper presents the proposition of a set of technical and managerial actions recommended for the management of energy in industry. Economic, environmental, political and social aspects have been putting pressure on the whole society for a more conscious and efficient use and consumption of energy in its diverse forms. Energy-intensive industries show a high energy consumption, they work with processes in severe temperature conditions, residual dissipation of heat and flux of not used residues, always being subject to great environment risks. These large-sized companies offer great opportunities for making energy more efficient, use of co-generation and various other possibilities for a better management and improvement of energetic performance. The research is characterized as quali-quantitative, exploratory and descriptive, presenting a statistical analysis for the questionnaire answers. The energy management practices refer to procedures used for dealing with energetic issues. In function of the interdisciplinary aspect of energy management in the industry, the management practices can be better understood with technical and managerial continuous or frequent actions. A Delphi study for verification of the validity of the proposed technical and managerial actions was carried out together with academia and industry specialists. The results show a favorable positioning, confirmed by a reliability rate among suitable evaluators (IRR - Inter Rater Reliability). The set of technical and managerial actions is made up of reference elements for creation, organization and conduction of an energy management system in the industry.

Abstract A lectin from the marine sponge Haliclona (Reniera) implexiformis (HiL) was isolated by affinity chromatography on Sepharose™ matrix. HiL showed specificity for galactose and its derivatives. The glycoproteins porcine stomach mucin (PSM) and bovine stomach mucin (BSM) were potent inhibitors. Hemagglutinating activity of the lectin was maximal between pH 5.0 and 9.0. The lectin remained active until 60°C. The presence of CaCl2 and EDTA did not affect the hemagglutinating activity. In SDS-PAGE, HiL showed a single band of 20 kDa under reduced conditions, whereas in the non-reducing conditions, it showed a band of 20 kDa and one additional band of 36 kDa. The average molecular mass determined by Electrospray Ionization Mass Spectrometry (ESI-MS) was 35.874 ± 2 Da in native and non-reducing conditions, whereas carboxyamidomethylated-lectin showed 18,111 Da. These data indicated that HiL consists in a dimer formed by identical subunits linked by disulfide bonds. Partial amino acid sequence of HiL was determined by mass spectrometry, and revealed that it is a new type of lectin, which showed no similarity with any protein. Secondary structure consisted of 6% α-helice, 31% β-sheet, 18% β-turn and 45% random coil. HiL showed significant reduction in the number of viable cells of Staphylococcus biofilms.

Abstract In the Amazon, local electrical energy production is very important due to the large number of isolated communities, usually far from the conventional grid. In this context, steam turbines are relevant technologies to be used in the region, since waste biomass is widely available in several communities, besides, where sustainable agricultural activities take place, such as the use of açaí seeds, sugarcane bagasse, among others. Currently, there are not many relevant studies in the literature for small steam turbines operating at low pressure, conditioned to the reality of the Amazon region. Hence, the main goal of this work is to develop an experimental study of a small steam turbine operating at low pressure, in order to apply it to small energy demand, typically found in the Amazon. We developed measurements on the behavior of mechanical and electrical powers in relation to the shaft rotational speed of the small steam turbine, taking into account pressures of 0.1, 0.2 and 0.3 MPa. We concluded that the preliminary experimental survey, made in this work, demonstrates a good mechanical behavior of the small turbine and could be an alternative for electricity generation system to supply small demands in isolated communities in the Amazon, taking advantage of biomass from sustainable agricultural activities.

Resumo Na Amazônia, a produção local de energia elétrica é muito importante devido ao grande número de comunidades isoladas, geralmente distantes da rede convencional. Nesse contexto, as turbinas a vapor são tecnologias relevantes a serem utilizadas na região, uma vez que a biomassa está amplamente disponível em diversas comunidades, inclusive, onde ocorrem atividades agrícolas sustentáveis como a utilização do caroço do açaí, bagaço de cana, entre outros. Atualmente, não existem muitos estudos relevantes na literatura para pequenas turbinas a vapor operando em baixa pressão, condicionadas à realidade da região amazônica. Assim, o objetivo principal deste trabalho é desenvolver um estudo experimental de uma pequena turbina a vapor operando em baixa pressão, a fim de aplicá-la a pequenas demandas de energia, tipicamente encontradas na região. Desenvolvemos medições do comportamento das potências mecânica e elétrica em relação à velocidade de rotação do eixo da pequena turbina a vapor, levando em consideração as pressões de 0,1, 0,2 e 0,3 MPa. Concluímos que o levantamento experimental preliminar, feito neste trabalho, demonstra um bom comportamento mecânico da pequena turbina e pode ser uma alternativa para o sistema de geração de energia elétrica suprir pequenas demandas em comunidades isoladas na Amazônia, aproveitando a biomassa oriunda de atividades agrícolas sustentáveis.

Abstract Every activity that involves exploitation of natural resources, such as fishing, needs to be organized and conducted based on information from monitoring programs to allow continuous evaluation. With the increasing fishing pressure in Brazil, the understanding of the importance of fisheries monitoring programs and how they can inform and assist in conservation decision-making remains limited. Based on the literature on fisheries and participatory conservation, we call attention to the need to generate information on the national fisheries sector in order to improve fisheries in the country. Given the context of the need to generate information on fishing stocks under exploitation, as well as to identify potential alternative fisheries and carry out various sectoral analyses in compliance with the 2030 Agenda for Sustainable Development, we present and discuss in the present paper the lack of a system of continuous fishing monitoring in Brazil and its effects on the fisheries sustainability in the country.

Resumo Toda atividade que atua envolvendo a exploração de recursos naturais, como a pesca, precisa ser organizada e conduzida com base nas informações dos programas de monitoramento para permitir uma avaliação contínua. Com o aumento da pressão pesqueira no Brasil, o entendimento da importância dos programas de monitoramento da pesca e como eles podem informar e auxiliar na tomada de decisões de conservação permanece limitado. Com base na literatura sobre pesca e conservação participativa, chamamos a atenção para a necessidade de gerar informações sobre o setor pesqueiro nacional para melhorar a pesca no país. Dado o contexto da necessidade de gerar informações sobre os estoques pesqueiros em exploração, bem como identificar potenciais alternativas de pesca e realizar diversas análises setoriais em conformidade com a Agenda 2030 para o Desenvolvimento Sustentável, é apresentada e discutida no presente trabalho a falta de um sistema de monitoramento contínuo da pesca no Brasil e seus efeitos na sustentabilidade da pesca no país.

ABSTRACT Leptocybe invasa is a fast-spreading alien pest infesting eucalyptus in several countries. This study examined the damage caused by the gall wasp, recorded in eucalyptus plants in the municipalities of Itaporanga D'Ajuda and São Cristóvão, state of Sergipe, Northeastern Brazil.

RESUMO Leptocybe invasa é uma praga exótica de rápida disseminação que infesta o eucalipto em vários países. Este estudo analisou os danos causados pela vespa-da-galha, registrados em plantas de eucalipto nos municípios de Itaporanga D'Ajuda e São Cristóvão, estado de Sergipe, Nordeste do Brasil.

Abstract A new lectin from marine sponge Ircinia strobilina, denominated IsL, was isolated by combination of affinity chromatography in Guar gum matrix followed by size exclusion chromatography. IsL was able to agglutinate native and enzymatically treated rabbit erythrocytes, being inhibited by galactosides, such as α-methyl-D-galactopyranoside, β-methyl-D-galactopyranoside and α-lactose. IsL hemagglutinating activity was stable at neutral to alkaline pH, however the lectin loses its activity at 40° C. The molecular mass determinated by mass spectrometry was 13.655 ± 5 Da. Approximately 40% of the primary structure of IsL was determined by mass spectrometry, but no similarity was observed with any protein. The secondary structure of IsL consists of 28% α-helix, 26% β-sheet, and 46% random region, as determined by dichroism circular. IsL was a calcium-dependent lectin, but no significant variations were observed by circular dichroism when IsL was incubated in presence of calcium and EDTA. IsL was not toxic against Artemia nauplii and did not have antimicrobial activity against bacterial cells. However, the IsL was able to significantly inhibit the biofilm formation of Staphylococcus aureus and Staphylococcus epidermidis.

■ ABSTRACT Introduction: Complex wounds are serious tegumentary injuries that are difficult to resolve with conventional dressings. This study aimed to describe a third-intention wound healing technique, reproducible and low cost, applicable to complex wounds, using polyvinyl chloride (PVC) prosthesis temporarily placed in the injured area to promote the protection and stimulate its “granulation,” followed by autologous partial-thickness skin grafting. Method: Consecutively, 20 patients with complex wounds resulting from external causes were selected and divided into 2 groups: A - patients who underwent the coverage technique with PVC prosthesis, followed by grafting, and B - patients submitted to the care of the dressing team, with daily changes until wound granulation, standard in our institution. Patients were evaluated regarding length of stay; costs; local pain; complications; the time until medical discharge; and patient satisfaction. Results: The length of hospital stay, its costs, and the time until medical discharge were shorter in group A (p<0.05). However, there was no statistically significant difference in local pain between techniques A and B. Conclusion: The technique using PVC prosthesis and graft has good efficacy for treating complex wounds, being reproducible and inexpensive.

■ RESUMO Introdução: Feridas complexas são lesões tegumentares graves, de difícil resolução com curativos convencionais. O objetivo deste estudo foi descrever uma técnica de cicatrização de feridas por terceira intenção, reprodutível e de baixo custo, aplicável a feridas complexas, utilizando uma prótese de policloreto de vinila (PVC) colocada temporariamente na área da lesão para promover proteção e estimular sua “granulação”, seguida de enxerto autólogo de pele de espessura parcial. Método: De forma consecutiva, foram selecionados 20 pacientes com feridas complexas, decorrentes de causas externas, divididos em 2 grupos: A - pacientes que foram submetidos à técnica de cobertura com prótese de PVC, seguida de enxerto; e B - pacientes submetidos aos cuidados da equipe de curativo, com trocas diárias até granulação da ferida, padrão da nossa instituição. Os pacientes foram avaliados quanto ao tempo de internação; custos; em relação à dor local; à presença de complicações; ao tempo até a alta médica; e à satisfação do paciente. Resultados: O tempo de internamento e seus custos, assim como o tempo até a alta médica, foram menores no grupo A (p<0,05). Todavia, não houve diferença estatisticamente significativa em relação à dor local entre as técnicas A e B. Conclusão: A técnica utilizando prótese de PVC e enxerto possui boa eficácia para o tratamento de feridas complexas, sendo reprodutível e de baixo custo.

Resumo Objetivou-se com o presente estudo determinar a melhor fonte e concentração de fosfito no controle da antracnose e seus efeitos nas características físicas e químicas em banana ‘Prata-anã’. Buquês de frutos de banana foram imersos em soluções contendo as diferentes formulações de fosfito de cobre FCu1 (4% de Cu + 20% de P2O5), FCu2 (4% de Cu + 22% de P2O5), nas concentrações de 0,5; 1,0; 1,5 e 2,0 mL L-1, e fosfito de potássio FK (42 % de P2O5 + 27,7% de K2O) nas concentrações de 0,5; 1,0; 1,5 e 2,0 mg L-1. As testemunhas consistiram na aplicação de água pura e aplicação do Imazalil (0,5 mL.L-1). Posteriormente, foram avaliadas a incidência e a severidade da antracnose a cada três dias. As características físicas e químicas dos frutos foram realizadas no término da avaliação da intensidade de antracnose. O delineamento experimental utilizado foi o inteiramente casualizado. Os resultados demonstraram que as diferentes fontes de fosfito FCu1, FCu2 e FK, nas concentrações testadas, não apresentaram eficácia no controle da antracnose. As características físicas e químicas dos frutos foram influenciadas pelas diferentes fontes e concentrações de fosfito aplicadas. A perda de massa fresca dos frutos é proporcional à concentração de fosfito aplicada.

Abstract The objective of the present study was to determine the best phosphite source and concentration to control anthracnose and its effects on the physical and chemical characteristics of ‘Prata-anã’ banana. Bouquets of banana fruits were immersed in solutions containing different formulations of copper phosphite FCu1 (4% Cu + 20% P2O5), FCu2 (4% Cu + 22% P2O5) at concentrations of 0.5; 1.0, 1.5- and 2.0-mL L-1 and potassium phosphite FK (42% P2O5 + 27.7% K2O) at concentrations of 0.5; 1.0, 1.5 and 2.0 mg L-1. Controls consisted of the application of pure water and Imazalil application (0.5 mL. L-1). Subsequently, anthracnose incidence and severity were evaluated every three days. The physical and chemical characteristics of fruits were evaluated at the end of the anthracnose intensity evaluation. The experimental design used was completely randomized. The results showed that the different phosphite sources FCu1, FCu2 and FK at the concentrations tested were not effective in controlling anthracnose. The physical and chemical characteristics of fruits were influenced by the different phosphite sources and concentrations applied. Fresh fruit mass loss is proportional to the applied phosphite concentration.

RESUMO Objetivo Analisar as percepções dos preceptores acerca do processo ensino-aprendizagem, bem como as fortalezas e as fragilidades para implementar as práticas colaborativas na Atenção Primária à Saúde. Método Pesquisa qualitativa, desenvolvida entre outubro e dezembro de 2019 com 96 preceptores (cirurgiões-dentistas, enfermeiros e médicos) da Estratégia de Saúde da Família. Os dados foram obtidos através de questionário e submetidos a Análise de Conteúdo, utilizando o software Maxqda-2020. Resultados Foram evidenciadas três categorias: 1. Um novo saber-fazer precisa ser ensinado a quem ensina, 2. o ensinar e o assistir no processo da preceptoria e 3. abordagem centrada na pessoa: paradigma para o trabalho colaborativo revelam dificuldades e tensões no trabalho do preceptor e de práticas colaborativas. Conclusão O estudo identificou a necessidade de qualificar os preceptores com novas abordagens para o desenvolvimento do processo ensino-aprendizagem, para o trabalho em equipe e práticas interprofissionais colaborativas no contexto da Atenção Primária à Saúde.

ABSTRACT Objective To analyze the perceptions of preceptors about the teaching-learning process, as well as the strengths and weaknesses to implement collaborative practices in Primary Health Care. Method Qualitative study carried out between October and December 2019 with 96 preceptors (surgeons- dentists, nurses and doctors) of the Family Health Strategy. Data were collected with the use of a questionnaire and submitted to Content Analysis, using the Maxqda-2020 software. Results Three categories were highlighted: 1. A new know-how needs to be taught to those who teach, 2. teaching and assisting in the preceptorship process and 3. person-centered approach: paradigm for collaborative work reveal difficulties and tensions in the preceptor work and collaborative practices. Conclusion The study identified the need to qualify preceptors with new approaches for the development of the teaching-learning process, for teamwork and collaborative interprofessional practices in the context of Primary Health Care.

RESUMEN Objetivo To analyze the perceptions of preceptors about the teaching-learning process, as well as the strengths and weaknesses to implement collaborative practices in Primary Health Care. Método Qualitative research, carried out between October and December 2019 with 96 preceptors (surgeons- dentists, nurses and doctors) of the Family Health Strategy. Data were obtained through a questionnaire and submitted to Content Analysis, using the Maxqda-2020 software. Resultados Three categories were highlighted: 1. A new know-how needs to be taught to those who teach, 2. teaching and assisting in the preceptorship process and 3. person-centered approach: paradigm for collaborative work reveal difficulties and tensions in the preceptor work and collaborative practices. Conclusión The study identified the need to qualify preceptors with new approaches for the development of the teaching-learning process, for teamwork and collaborative interprofessional practices in the context of Primary Health Care.

RESUMO: Objetivo: Descrever o desempenho da atenção primária à saúde, segundo clusters de municípios paulistas que apresentaram indicadores homogêneos. Métodos: Trata-se de um estudo descritivo, com base em dados secundários extraídos de fontes oficiais do Sistema Único de Saúde, referentes ao ano de 2018. Foi elaborada uma matriz de análise, com a proposição de indicadores de desempenho (acesso, efetividade e adequação) e contexto (população, determinantes de saúde e financiamento), selecionados e organizados em dimensões e subdimensões. Para identificar os grupos de municípios homogêneos, foi utilizada a análise de cluster Resultados: Dos 645 municípios, constituíram-se seis clusters. Os clusters 2 e 3 foram formados, predominantemente, por municípios pequenos e com maior acesso; entre eles, o cluster 3 apresentou menor vulnerabilidade social e maior investimento em saúde. Os clusters 1, 4 e 5, em contrapartida, foram formados por municípios maiores e com menor acesso; entre eles, o cluster 4 apresentou maior vulnerabilidade social, menor cobertura de planos privados de saúde e maior percentual de recursos utilizados em saúde; e o cluster 5, maior produto interno bruto per capita e maior cobertura de planos privados de saúde. O cluster 6, formado pelo município de São Paulo, demonstrou ser um caso particular. Ainda, o cluster 2 chamou atenção. Apresentando maior cobertura, sinalizou menor efetividade e adequação. Entre todos os clusters, o cluster 3 alcançou o melhor desempenho. Conclusão: Os resultados podem subsidiar a gestão regional e municipal, diante da complexidade do território paulista, apontando para cenários que demandam maiores inciativas de gestão pública.

ABSTRACT: Objective: To describe the performance of Primary Health Care, according to conglomerates of São Paulo cities that present homogeneous indicators. Methods: This is a descriptive study, based on secondary data extracted from official sources of the Unified Health System, for the year 2018. An analysis matrix was created, with the proposition of performance (access, effectiveness and adequacy) and context indicators (population, health determinants and financing) selected and organized in dimensions and sub-dimensions. Cluster Analysis was used to identify the groups of homogeneous municipalities. Results: 645 municipalities were divided in 6 conglomerates. Clusters 2 and 3 were formed predominantly by small municipalities with greater access to health; cluster 3 has less social vulnerability and greater investment in health. Clusters 1, 4 and 5 were formed by the largest municipalities with less access to health; cluster 4 presents greater social vulnerability, less coverage of private health plans and a greater percentage of health resources; cluster 5 was characterized by greater Gross Domestic Product per capita and greater coverage of private health plans. Cluster 6, formed by the city of São Paulo, was a particular case. Cluster 2 drew attention, as it was shown to have increased coverage, but signaled lower efficacy and adequacy levels. Cluster 3 had the best performance among all clusters. Conclusion: These findings can support regional and municipal management, given the complexity of the territory of São Paulo, pointing to scenarios that demand broader public management initiatives.

RESUMO: Objetivo: Descrever o desempenho da atenção primária à saúde, segundo clusters de municípios paulistas que apresentaram indicadores homogêneos. Métodos: Trata-se de um estudo descritivo, com base em dados secundários extraídos de fontes oficiais do Sistema Único de Saúde, referentes ao ano de 2018. Foi elaborada uma matriz de análise, com a proposição de indicadores de desempenho (acesso, efetividade e adequação) e contexto (população, determinantes de saúde e financiamento), selecionados e organizados em dimensões e subdimensões. Para identificar os grupos de municípios homogêneos, foi utilizada a análise de cluster Resultados: Dos 645 municípios, constituíram-se seis clusters. Os clusters 2 e 3 foram formados, predominantemente, por municípios pequenos e com maior acesso; entre eles, o cluster 3 apresentou menor vulnerabilidade social e maior investimento em saúde. Os clusters 1, 4 e 5, em contrapartida, foram formados por municípios maiores e com menor acesso; entre eles, o cluster 4 apresentou maior vulnerabilidade social, menor cobertura de planos privados de saúde e maior percentual de recursos utilizados em saúde; e o cluster 5, maior produto interno bruto per capita e maior cobertura de planos privados de saúde. O cluster 6, formado pelo município de São Paulo, demonstrou ser um caso particular. Ainda, o cluster 2 chamou atenção. Apresentando maior cobertura, sinalizou menor efetividade e adequação. Entre todos os clusters, o cluster 3 alcançou o melhor desempenho. Conclusão: Os resultados podem subsidiar a gestão regional e municipal, diante da complexidade do território paulista, apontando para cenários que demandam maiores inciativas de gestão pública.

ABSTRACT: Objective: To describe the performance of Primary Health Care, according to conglomerates of São Paulo cities that present homogeneous indicators. Methods: This is a descriptive study, based on secondary data extracted from official sources of the Unified Health System, for the year 2018. An analysis matrix was created, with the proposition of performance (access, effectiveness and adequacy) and context indicators (population, health determinants and financing) selected and organized in dimensions and sub-dimensions. Cluster Analysis was used to identify the groups of homogeneous municipalities. Results: 645 municipalities were divided in 6 conglomerates. Clusters 2 and 3 were formed predominantly by small municipalities with greater access to health; cluster 3 has less social vulnerability and greater investment in health. Clusters 1, 4 and 5 were formed by the largest municipalities with less access to health; cluster 4 presents greater social vulnerability, less coverage of private health plans and a greater percentage of health resources; cluster 5 was characterized by greater Gross Domestic Product per capita and greater coverage of private health plans. Cluster 6, formed by the city of São Paulo, was a particular case. Cluster 2 drew attention, as it was shown to have increased coverage, but signaled lower efficacy and adequacy levels. Cluster 3 had the best performance among all clusters. Conclusion: These findings can support regional and municipal management, given the complexity of the territory of São Paulo, pointing to scenarios that demand broader public management initiatives.

ABSTRACT The increase of H. pylori resistance to clarithromycin is a concern. This study evaluated the prevalence of H. pylori’s primary resistance to clarithromycin and its association with virulence factors in adult dyspeptic patients and asymptomatic children. The gastric mucosa from patients (153 gastritis, 24 gastric cancer, 21 peptic ulcer) and gastric juice obtained by string test from 24 H. pylori and 23S rRNA positive asymptomatic children were included. The clarithromycin resistance was assessed by TaqMan RT-PCR 23S rRNA point mutations, A2142G and/or A2143G, and H. pylori virulence markers by PCR. Overall, the clarithromycin resistance was 14.4% (32/222), 14.2% in adults, and 12% in children, whereas origin, gender, and disease were not distinctive factors. The most prevalent point mutation was A2143G (62.5%). The point mutation was significantly less frequent in cagA-positive (11.4%) than in cagA-negative (23.6%) strains (p=0.03 OR = 0.4 95%CI = 0.19 - 0.91) as well as in cagE-positive (10.2%), cagE-negative (21.2%) (p=0.03 OR: 0.4 I.C:0.20-0.91). No difference was found in iceA or vacA alleles genotypes. Primary resistance to clarithromycin was lower than that reported in Southeast Brazil. The cagA and cagE positive H. pylori samples have few point mutations suggesting that individuals infected with virulent strains may be more susceptible to anti-H. pylori treatment.

ABSTRACT Bases are chemical species that donate electrons, accept protons, or release hydroxyls (OH–) in aqueous solution. In Soil Science, “base saturation”, “exchangeable bases” or “basic cations” has been widely used to distinguish Ca2+, Mg2+, Na+, and K+ from H+ and Al3+ cations. This terminology is confusing since none of these cations are truly a base in chemistry sense. However, in the absence of the proposition of a correct term, the term “base saturation” remains in use nowadays, causing confusion among students, professionals, and even among professors and researchers in Soil Science, as it leads to the erroneous interpretation that the soil acidity can be corrected by adding these cations to the soil. Here, we present the historical background of this nomenclature and a theoretical foundation that justifies the abolition of the use of these terms in Soil Science. We consider that the most correct is to call it “Ca-Mg-K-Na saturation”, which, despite being long, would refer directly and without any misinterpretation of the terminology. In Soil Fertility, the “base saturation” is often calculated only as a function of the sum of Ca, Mg, and K, since the Na content is negligible in most tropical and subtropical soils. Thus, one could use the term “Ca-Mg-K saturation”. Likewise, it is also suggested to abolish the use of the term “sum of bases” and use the term “sum of Ca-Mg-K” or “sum of Ca-Mg-K-Na” instead when necessary.

RESUMO Este estudo avalia o efeito da associação dos tratamentos térmicos de recozimento e desestabilização na precipitação e morfologia de carbonetos secundários e na dureza de uma liga de ferro fundido branco alto cromo (FFBAC) com adição de nióbio. O ferro fundido branco alto cromo é utilizado na fabricação de componentes envolvendo solicitações de desgaste, principalmente nas indústrias mineradoras, em equipamentos como chutes de transporte de minério, devido à sua elevada dureza e alta resistência ao desgaste abrasivo. Os tratamentos térmicos visam melhorar as propriedades mecânicas, por meio da precipitação de carbonetos secundários e da obtenção de matrizes martensíticas. A adição de cromo nos ferros fundidos tem como finalidade formar carbonetos e elevar a dureza da liga. A metodologia utilizada foi a fundição do material com adição de 0,5% de nióbio como elemento de liga e a caracterização metalográfica por meio de microscopias ópticas e eletrônicas, bem como a quantificação de carbonetos e a realização de ensaios de dureza. Foram analisadas amostras desestabilizadas sem e com recozimento prévio e foi verificado que o recozimento favoreceu uma maior precipitação de carbonetos secundários M7C3, possibilitando uma redução no tempo de tratamento térmico de desestabilização e a transformação da matriz austenítica em martensítica durante o resfriamento, promovendo um aumento da dureza.

ABSTRACT This study evaluates the effect of association annealing and destabilizing heat treatments in precipitation and morphology of secondary carbides and hardness in a high-chromium white cast iron alloy with the addition of niobium. White cast iron is used in the manufacture of components involving wear requests, mainly in the mining industries, in equipment such as ore transport chutes, due to its high hardness and high strength to abrasive wear. The heat treatments aim to improve the mechanical properties, through the precipitation of secondary carbides and the obtaining of martensitic matrices. The addition of chromium in cast irons aims to form carbides and increase the hardness of the alloy. The methodology used was the casting of the material with the addition of 0.5% niobium as an alloying element and metallographic characterization by means of optical and electronic microscopy techniques, as well as the quantification of carbides and performance of hardness tests. Destabilized samples were analyzed without and with previous annealing and it was verified that the annealing favored a greater precipitation of secondary carbides M7C3, allowing a reduction in the thermal treatment time of destabilization and the transformation of the austenitic matrix into martensitic during the cooling, promoting an increase in hardness.

Abstract High chromium cast iron (HCCI) with levels around 26% Cr - 2.9% C according to ASTM A 532 IIIA is widely used in systems where high abrasive wear resistance is required. To evaluate the niobium influence, HCCI with 0.5% Nb and 1% Nb additions were melted, besides one without niobium addition of for comparison. For characterization, X-ray diffractometry, scanning electron microscopy (SEM), Vickers microhardness tests, Rockwell C hardness, carbide quantifications, quantification of the retained austenite by Mössbauer spectroscopy, and rubber wheel abrasion test according to procedure A of ASTM G-65 were performed. The results indicated a reduction in the average size, average perimeter, and carbides volumetric fraction (CVF) due to the addition of niobium, also changing the microstructure of the HCCI from eutectic to hypoeutectic. In some regions, NbC0.75 carbides formed a coating around M7C3 carbides. The 0.5% Nb alloy showed the best performance in the rubber wheel abrasive wear test, with a 37% average volume loss reduction as compared to the sample without niobium addition with a 130N load and 34% with a 45N load. The 0.5% Nb alloy also had the highest content of retained austenite among the investigated alloys.