Navegando por Assunto "Characterization"

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Acesso aberto (Open Access)
Caracterização de tintas industriais aplicadas na região amazônica a partir de análises físico-químicas, mecânicas e de durabilidade
(Universidade Federal do Pará, 2024-02-28) LUCAS, Mathaus Moraes; SILVA, Alisson Clay Rios da; http://lattes.cnpq.br/7389345867032737; https://orcid.org/0000-0001-9186-2287
In Brazil, the industrial sector of paints and varnishes is among the five largest in the market. The manufacture of paints for various applications, with technology and technical responsibility, equals the most advanced global production centers. The durability of a paint refers to its resistance to weathering. For weathering, a weather-resistant paint is necessary so that fading does not occur on the substrate where it will be used, which can occur among some factors, due to the incidence of sunlight and heavy rains. The North region, with high rainfall, influenced by instability lines, presents significant spatial and seasonal heterogeneity of rainfall and has the highest annual rainfall total. Given this reality, a paint commercially applied in the Amazon region was developed. In the standard formulation, variations of mineral loads (Kaolin, Dolomite and Precipitated Calcium Carbonate) were made and subsequently analyses and tests were carried out to evaluate the performance of this paint, compared with the original formulation, such as abrasion resistance and weathering resistance. The paint production methodology will be according to Castro (2009) using Hare’s technique (1974). The characterization of the paints in the fresh state was carried out through the Viscosity, pH and specific weight tests, while the characterization of the paints in the hardened state was carried out through the abrasion resistance tests, weathering resistance test and Scanning Electron Microscopy. The physico-chemical tests revealed that, in relation to Stormer viscosity, all formulations exceeded the standard (130 KU), with the exception of the paints containing 30% Dolomite, 15% PCC, 15% Dolomite and the ternary combination of 5% Kaolin, 5% Dolomite and 20% PCC. As for the specific weight, the formulation that came closest to the standard was the binary paint with 15% Kaolin and 15% PCC, presenting an average value of 1.43 g/cm³. In terms of pH, all formulations showed alkalinity, with values ranging between 7.5 and 9.6. After a period of exposure of 180 days, none of the mixtures, including the standard formulation, showed the formation of pathologies, demonstrating resistance to weathering. The formulations with 30% Dolomite; 15% PCC and 15% Dolomite; 5% PCC, 5% Kaolin and 20% Dolomite; 10% Kaolin, 10% PCC and 10% Dolomite, exhibited respectively 300, 290, 240, 270 cycles of abrasion resistance, indicating the potential of these paints for a variety of applications, such as floor paints, external paints and road paints.
Acesso aberto (Open Access)
Caracterização fisico-quimica de lixiviado bruto e tratado por osmose reversa de aterro sanitário no estado do Pará
(Universidade Federal do Pará, 2023-03-27) PEREIRA, Filipe Castro; MENDONÇA, Neyson Martins; http://lattes.cnpq.br/7534816053779593
The effluent generated inside landfills is called leachate. The characterization of the leachate generated in landfills is important to indicate its polluting potential and enable the application of techniques for its treatment. Thus, this work aims to characterize quantitatively and qualitatively the leachate from landfills located in the state of Pará. In addition, it aims to calculate the value of IPL for this leachate in order to know its potential contamination by comparing the results with those obtained by other authors. To this end, the work was divided into three phases, where the first was about the quantitative evaluation of the leachate, the second corresponded to the qualitative evaluation and the third is related to the calculation of the polluting potential of the leachate. The quantitative characterization had as a result a strong connection of the leachate input flow with rainfall, where it was noted an increase in flow when comparing the year 2018 with the year 2019, explained by the expansion of the landfill and the increase in the capacity of theLeachate Treatment Plant (LTP). The qualitative characterization showed a leachate with high organic matter contents and high fouling potential. The results of the third phase pointed out that the IPL methodology is not suitable for Brazilian leachates, being the Index of Deactivated Landfill (IDL) a more appropriate index for it. Thus, it is concluded that the leachate from Marituba landfill has a high complexity and should go through advanced treatment processes.
Acesso aberto (Open Access)
Caracterização mecânica e metalúrgica de parafusos da classe 10.9, utilizados na fixação da suspensão dianteira de veículos CAT793D, aplicando tratamento termoquímico de cementação
(Universidade Federal do Pará, 2022-08-31) RABELO JÚNIOR, Fábio Alves; CARDOSO FILHO, José Carlos de Araújo; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
When a structural component of a large piece of equipment fails, catastrophic consequences can occur, generating highly measurable economic losses, because a failure leads to an interruption of an entire production line and damage to the workflow, which can cause delays and increased maintenance costs, whether preventive or corrective. In addition, serious risk conditions affect the loss of life in cases of catastrophic accidents, where they are widely reported by the media and strongly influence an organization's conduct. The objective of this work is to carry out the mechanical and metallurgical characterization of screws of class 10.9, applying the Thermochemical Treatment of Cementation, evaluating the influence of this mechanical resistance. These components include the Caterpillar model 793D “Off-Highway” truck suspension system that carries heavy iron ore loads in the Ferro-Carajás complex, in the state of Pará. Thermo-chemical treatments and mechanical tests were carried out and Tensile Stress. Fractographic and Microstructural analyzes were performed using Scanning Electron Microscopy - SEM, in addition to Optical Microscopy.
Acesso aberto (Open Access)
Estudo da incorporação de resíduos industriais, lama vermelha e caulim, nas propriedades de compósitos de matriz poliéster reforçados com fibras de juta e malva
(Universidade Federal do Pará, 2022-07-18) RIBEIRO, Maurício Maia; SILVA, Alisson Clay Rios da; http://lattes.cnpq.br/7389345867032737; https://orcid.org/0000-0001-9186-2287; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809; https://orcid.org/0000-0002-3926-0403
The Amazon region of Brazil is a major producer of bauxite and kaolin, with the state of Pará accounting for a large national share of the production of these materials. The processing of these raw materials generates considerable amounts of waste that is then stored in sedimentation ponds which can cause serious environmental damage, therefore it is very important to explore reasonable methods of utilizing the red mud and kaolin waste, and thus reduce their landfill volumes. Many recent studies have been conducted and presented various ways of comprehensive utilization of these wastes. Natural fiber reinforced composites with insertion of these industrial wastes have received increasing attention in recent decades, as good specific mechanical properties can be achieved and industrial wastes can be reduced and used in a useful form. In this work, polyester matrix composite materials reinforced by jute and mallow fibers in continuous configuration and aligned at 0° and 90° in the loading direction, and composite materials with insertion of industrial waste were manufactured. The polyester matrix used was a pre-accelerated orthophytalic and cured at room temperature with methyl ethyl ketone peroxide 1.0% by mass. The Jute and mallow fibers were manually cut in length of 300 mm and manually arranged in a continuous manner and aligned and without surface treatment. Fiber composites were produced by vacuum-assisted hand lay-up/vaccum-bagging procedure. The proportions of the fiber volume fraction have varied by 5, 15 e 25 %. The composites with kaolin and red mud residues were manufactured by a manual process in the form of silicone and pressed mold. The proportions of the mass fractions of waste have varied by 5, 10, 15, 20, 25 e 30 %. The residues were characterized in terms of their physical, morphological and chemical aspects and the fibers in terms of their physical and mechanical aspects and the experimental values are similar to that presented from old newspaper. Just as the composites manufactured had their specific mass determined, which resulted in an increase in the average value of the specific mass of the composites with insertion of red mud and kaolin residues. In the case of composites reinforced with fibers of jute and mallow, there was a reduction in the average value when compared to the matrix. Tensile and shear properties were observed for the composites with industrial waste, red mud and kaolin. The composite 5RC exhibited tensile strength value closer to the matrix, as well as for 5RLV, 10RLV and 15 RLV which exhibited the same behavior. For shear strength the composites 10RLV and 15 RLV were closer to the matrix. As well as the composites reinforced with jute fibers 0° presented the highest tensile strength were 0J5, 0J15 and 0J25, exceeding in 2%, 150% and 166% the tensile strength of polyester. For the composites reinforced with mallow fibers 0° showed the highest tensile strength were 0M15 and 0M25, exceeding in 67% and 96% the tensile strength of polyester. For shear strength the composites reinforced with jute (0J15 and 0J25) and mallow (0M15 and 0M25) fibers exceeded the matrix in 201%, 206%, 71% and 144%, respectively. The tensile strength of the three-phase composites (0JRLV, 0JRC, 0MRLV and 0MRC) exceeded the matrix by 129|%, 100%, 54% and 21%, respectively. For shear strength they exceeded the matrix by 49%, 47%, 63% and 52%. Composites with 0-aligned fibers showed satisfactory mechanical behavior for application in composite materials presenting reinforcement characteristics.
Acesso aberto (Open Access)
Estudo dos constituintes dos produtos de pirólise visando a produção de biocombustíveis e químicos
(Universidade Federal do Pará, 2020-09-21) FERREIRA, Márcia de Fátima Pantoja; RIBEIRO, Nielson Fernando da Paixão; http://lattes.cnpq.br/0755443458423442; https://orcid.org/0000-0001-6145-7993; FRANÇA, Luiz Ferreira de; http://lattes.cnpq.br/6545345391702172
This work aims to use slow pyrolysis in biomass residues (EFB) as an energy potential in the production of biofuels. The raw material was obtained from agribusiness and subjected to washing, drying and crushing. The experiments were carried out in a fixed bed reactor and the central rotational composite design was used to optimize the variables temperature (459, 500, 600, 700, 741 °C) and carrier gas flow (0.259; 0.3; 0.4; 0.5 and 0.541 L/min), in order to identify the ideal conditions for obtaining bio-oil (BO). From the optimized result, the products were characterized using various techniques (FTIR, CG / MS, HPTLC, NMR, MEV, humidity, CHNO). Temperature was the most influential parameter in relation to liquid and solid yields, and the combination of variables influenced the yield in gas. There was a higher yield in BO (45.29%) whose composition showed a large amount of fatty acids, alkanes, alkenes and phenolic compounds, the latter with high antioxidant capacity. Biochar showed low yield (27.52%), but good energy capacity, the gas yield was 27.89%. The calorific value of the BO was 24.48 MJ/kg and the biochar was 19.27 MJ/kg. The results of the techniques used, prove the use of EFB as a renewable source in obtaining biofuels.
Acesso aberto (Open Access)
Percurso de estudo e pesquisa: condições e restrições reveladas pelas teses defendidas no Brasil na área da educação matemática de 2011 a 2021
(Universidade Federal do Pará, 2023-05-04) BARRETO, Saul Rodrigo da Costa; ALMOULOUD, Saddo Ag; http://lattes.cnpq.br/9168215683139657; https://orcid.org/0000-0002-8391-7054; NUNES, José Messildo Viana; http://lattes.cnpq.br/5188612973174798; https://orcid.org/0000-0001-9492-4914
This research is a doctoral thesis of the Graduate Program in Science and Mathematics Education (PPGECM) of the Federal University of Pará (UFPA). It consists of qualitative bibliographical research. For its accomplishment we started from the following research questions: "What are the conditions and restrictions of those who applied a Study and Research Path - SRP? What are the advances and perspectives of SRP in the context of mathematics teaching and learning? To answer these questions, we conducted a systematic review of the literature using a systematic review protocol, and then we conducted an analysis of selected doctoral research in Brazil from 2011 to 2021, through a qualitative meta-synthesis focusing on theses that made use of the didactic methodological device SRP. We assume as hypotheses that: a) through the studies of research that used the SRP in Brazil, we can identify characteristic elements of manipulation of a SRP, being possible to reveal the conditions and constraints of its development, as well as the advances of the SRP regarding the teaching and learning of Mathematics in Brazil; b) from the characterization of SRP emanate perspectives that allow us to categorize them. The general objective of this study was to describe the main characteristics of the use of SRP in Mathematics Education theses defended in Brazil, from 2011 to 2021. As specific objectives, we defined the following: a) to make a panorama of researches with SRP in Brazil from its characterization; b) to identify the main research problems of the analyzed theses, seeking to characterize the main elements that compose a SRP; c) to elaborate comparative charts of SRP characteristics and to create categories. Chevallard's Anthropological Theory of Didactics (ATD) is the main structural basis of the research, since its elements guarantee a consistent SRP and provide us with subsidies for the analysis of this device. As results, state-of-the-art tables were elaborated that revealed main characteristics that delineate a SRP, such as: classification of the SRP; composition of the SRP systems; starting point of the WBS; emergence of the generating question Q; dynamics of emergence and unfolding of the question Q; dynamics of construction of the answer R to the question Q from the study, deconstruction, questioning and reconstruction of R (answers to the questions Qi generated from the question Q) and from the studies of the works; particularities of the production functions: chronogenesis, mesogenesis and topogenesis; structuring principles of the SRP and the corresponding dialectics. Thus, the analyses of characteristics in the selected research, was determinant to reveal conditions and restrictions of didactic and adidactic interventions through the SRP device, which contributed to reveal a panorama of SRP in Brazil and more precisely, assisted in the categorization of the types of SRP.
Acesso aberto (Open Access)
Resíduo do lodo da estação de tratamento de água da Região Metropolitana de Belém em substituição parcial ao cimento Portland em argamassa
(Universidade Federal do Pará, 2019-04-25) CUNHA, Bruna Baia da; PICANÇO, Marcelo de Souza
As a result of the growth of cities and the greater demand for quality of life, the demand for drinking water has increased in recent decades. Like any industrial process, the production of water for human use generates large quantities of by-products, being the main designated residue of waste, sludge or sludge of Water Treatment Station (WTPS). So far, the most common destination for the WTPS is the watercourse, although it is considered a solid waste. These factors motivate research aimed at alleviating the problems caused by incorrect waste disposal in the environment. In this sense, the present paper presents an alternative proposal for the disposal of WTPS in mortar, partially replacing cement, whose extraction and employment also cause environmental impact. The WTPS was used in the mortar with the least possible alteration of the residue, that is, its in natura use to avoid energy expenditure and to enable its use. The characterization of the materials used, as well as the physical, chemical, mineralogical and thermal characterization of the sludge extracted from WTP Bolonha, located in the metropolitan area of Belém, was carried out. The analyzes provided data that were the basis for investigations of viable applications for the residue. The first investigation studied its use as pozzolan in Portland cement, for which the tests that analyzed its potential reactivity with lime and cement were carried out. The investigation of the pozzolanic activity, both with lime and cement CP II-F-32, showed that mortars with replacement contents obtained lower results than required by the respective standards, discarding their use for this purpose. The second research analyzed the effects of the use of the residue as a filler in Portland cement, the reference mortar (without addition of sludge) and traces with additions of 6, 8 and 10% were used. In the compressive strength the 6% replacement content of the cement Portland CP I-25 by WTPS produced a resistance increase of 8,93% at 7 days and 3,24% at 28 days of age, in relation to the reference mortar, besides absorbing 7,81% water less than conventional mortar. Although the use of sludge occurs in small quantities, its use is feasible, since its incorporation will reduce the consumption of the raw material required for the production of mortar.