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URI Permanente para esta coleçãohttps://repositorio.ufrn.br/handle/1/182

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Analysis and evaluation of shape memory alloy wires behaviour in weft-knitted fabrics
(Trans Tech Publications, 2012-11) Medeiros, José Ivan de; Fangueiro, Raul
It is widely acknowledged within the textile engineering community that Shape Memory Alloys (SMA), exhibit great potential for several applications. This paper presents the research undertaken at the University of Minho aiming to study the behaviour of weft-knitted fabrics produced with SMA nitinol® wires. SMA nitinol® wires of type B (which shows shape memory effect at body temperature) of 50, 127 and 210 µm diameters have been used to produce weftknitted fabrics with different loop types, e.g. stitch, tuck and miss. The influence of the loop type on the performance of the weft-knitted fabric, in terms of energy absorption, has been analyzed. Tensile tests were carried out according to ISO1462 standard, using a H100KS Hounsfield universal testing instrument. The results aim to help future applications of SMA in the development of new textile materials
Analysis of energy absorption for NiTi wires under different diameters and loop types
(The Textile Machinery Society of Japan, 2013) Medeiros, José Ivan de; Fangueiro, Raul
This paper presents the research undertaken at the University of Minho aiming to study the behaviour of 3D weft-knitted structures using Shape Memory Alloy (SMA) wires and elastomeric yarns, in order to produce dynamic structures as a support to answer specific situations and applications. Several samples were produced using NitinolR wires in different diameters and loop types. The Tensile tests were carried out being based to NP EN ISO 2062: 1993 standards, using a H100KS Hounsfield Universal Testing Instrument. The results showed that The 50 μm wire showed to be too thin to this propose;moreover, The 210 μm NiTi wire showed to be hard to process on the knitting machine due to its high stiffness;The 127 μm NiTi wire showed to be the best among them, due to the process and energy absorption ratio. Finally, for both NiTi wires in different diameters studied, tuck loop showed to have the highest energy absorption capacity
Antimicrobial efficacy of low concentration PVP-silver nanoparticles deposited on DBD Plasma-Treated polyamide 6,6 fabric
(Coatings, 2020-04-10) Silva, Késia Karina de Oliveira Souto; Ribeiro, Ana Isabel; Senturk, Dilara; Modic, Martina; Cvelbar, Uros; Dinescu, Gheorghe; Mitu, Bogdana; Nikiforov, Anton; Leys, Christophe; Kuchakova, Irina; Vrieze, Mike de; Souto, António Pedro; Zille, Andrea
In this study, a low concentration (10 μg·mL−1) of poly(N-vinylpyrrolidone) (PVP)-coated silver nanoparticles (AgNPs) were deposited by spray and exhaustion (30, 70 and 100 ◦C) methods onto untreated and dielectric barrier discharge (DBD) plasma-treated polyamide 6,6 (PA66) fabric. DBD plasma-treated samples showed higher AgNP deposition than untreated ones for all methods. After five washing cycles, only DBD plasma-treated samples displayed AgNPs on the fabric surface. The best-performing method was exhaustion at 30 ◦C, which exhibited less agglomeration and the best antibacterial efficacy against S. aureus (4 log reduction). For E. coli, the antimicrobial effect showed good results in all the exhaustion samples (5 log reduction). Considering the spray method, only the DBD plasma-treated samples showed some bacteriostatic activity for both strains, but the AgNP concentration was not enough to have a bactericidal effect. Our results suggest DBD plasma maybe a low cost and chemical-free method for the preparation of antibacterial textiles, allowing for the immobilization of a very low—but effective—concentration of AgNPs
Application of nitriding and duplex treatment on steel drills-HSS
(JMEST, 2020-04) Feitor, Michelle Cequeira; Serra, Petteson Linniker Carvalho; Sousa, Rômulo Ribeiro Magalhães de; Barros Neto, João Rodrigues de; Libório, Maxwell Santana; Costa, Thércio Henrique de Carvalho
The present study aims to evaluate the application of plasma nitriding (at temperatures of 450° and 500°C) and duplex treatment (conventional nitriding followed by TiN deposition, using the cathodic cage deposition technique). Samples were characterized by Vickers Microhardness Test, Scanning Electron Microscopy-SEM, and Energy Dispersion Spectroscopy-EDS. Drill performance was evaluated after machining SAE1045 steel specimens, using flank wear and hole diameter measurements. The performance test pointed to the viability of the treatment at 450°C, whose treated drill had a longer life than in the untreated drill, in addition to meeting the dimensional quality in all holes. In contrast, the other tools, nitrided at 500°C and submitted to the duplex treatment, they presented performance below the expected, not showing viability for application in these conditions. Additionally, it was observed the existence of a thermal gradient formed during the treatment
Azilsartan Increases Levels of IL-10, Down-Regulates MMP-2, MMP-9, RANKL/RANK, Cathepsin K and Up- Regulates OPG in an Experimental Periodontitis Model
(Faculté de Médecine de Nantes, France, 2014-05-12) Araújo, Aurigena Antunes de; Varela, Hugo; Brito, Gerly Anne de Castro; Medeiros, Caroline Addison Carvalho Xavier de; Araújo, Lorena de Souza; Nascimento, José Heriberto Oliveira do; Araújo Júnior, Raimundo Fernandes de
Aims The aim of this study was to evaluate the effects of azilsartan (AZT) on bone loss, inflammation, and the expression of matrix metallo proteinases (MMPs), receptor activator of nuclear factor κB ligand (RANKL), receptor activator of nuclear factor κB (RANK), osteoprotegerin (OPG), cyclooxygenase-2 (COX-2), and cathepsin K in periodontal tissue in a rat model of ligature-induced periodontitis. Materials and Methods Male Wistar albino rats were randomly divided into 5 groups of 10 rats each: (1) nonligated, water; (2) ligated, water; (3) ligated, 1 mg/kg AZT; (4) ligated, 5 mg/kg AZT; and (5) ligated, 10 mg/kg AZT. All groups were treated with saline or AZT for 10 days. Periodontal tissues were analyzed by histopathology and immunohistochemical detection of MMP-2, MMP-9, COX-2, RANKL, RANK, OPG, and cathepsin K. Levels of IL-1β, IL-10, TNF-α, myeloperoxidase (MPO), and glutathione (GSH) were determined by ELISA. Results Treatment with 5 mg/kg AZT resulted in reduced MPO (p<0.05) and IL-1β (p<0.05), increased levels of IL-10 (p<0.05), and reduced expression of MMP-2, MMP-9, COX-2, RANK, RANKL, cathepsin K, and increased expression of OPG. Conclusions These findings reveal that AZT increases anti-inflammatory cytokines and GSH and decreases bone loss in ligature-induced periodontitis in rats.
Caracterização de filmes de poliéster modificados por plasma de O2 a baixa pressão
(Universidade Federal do Rio de Janeiro, 2008-05-12) Costa, Thércio Henrique de Carvalho; Feitor, Michelle Cequeira; Alves Junior, Clodomiro; Bezerra, Clovis de Medeiros
Filmes de poliéster possuem um vasto campo de aplicação, devido algumas propriedades que são inerentes desse tipo de material, tais como boa resistência mecânica, resistência química a ácidos e bases e baixo custo de produção. Entretanto possuem limitações, como baixa tensão superficial, baixa rugosa, pouca afinidade com corantes, e pouca adesão, que impedem o uso dos mesmos para algumas finalidades principalmente quando esse uso requer que o material possua uma boa molhabilidade. Dentre as varias técnicas existentes para aumentar a tensão superficial, as técnicas que utilizam o plasma, como fonte energética, são as mais promissoras pela versatilidade e por não apresentar agentes nocivos ao meio. Então, tendo em vista a boa aceitabilidade do uso do plasma em materiais poliméricos, trataram-se filmes de poliéster usando plasma com atmosfera gasosa de oxigênio variando-se o tempo de tratamento de 10 - 60 min com incremento de 10 min a cada tratamento subseqüente. Após o tratamento por plasma as amostras foram caracterizadas por medidas de ângulo de contato, tensão superficial, espectroscopia Raman, Espectroscopia de infravermelho de reflexão total atenuada (IR-ATR), e microscopia de força atômica (AFM), onde foi caracterizado o aumento na molhabilidade dos filmes tratados por plasma bem como as variáveis que contribuíram para tal efeito. A técnica de plasma mostrou-se bastante eficiente na modificação de filmes de poliéster, uma vez que se obteve aumento na molhabilidade de todos os filmes tratados e sem nenhuma variação significativa com relação ao tempo de exposição das amostras pelo plasma, o que leva a propor que o tratamento por plasma tanto contribuiu para o aumento da molhabilidade através da implementação de grupos funcionais na superfície dos mesmos como com a criação de rugosidade superficial nas amostras
Characterization and acidic properties of AlMCM-41 prepared by conventional and post-synthesis alumination
(Australian Journal of Chemistry, 2015) Nascimento, Rubens Maribondo do; Costa, Maria José Fonseca; Chellappa, Thiago; Araujo, Antonio Souza de; Fonseca, Viviane Muniz; Fernandes Júnior, Valter José; Pacheco, Jose G. A.
The catalysts analysed in the current work are variations of MCM-41. The properties of these highly ordered mesoporous aluminosilicates were adjusted by an isomorphous substitution of Si by a trivalent cation, in this case Al3þ, generating catalysts of the AlMCM-41 type. The materials were synthesized with a silicon/aluminium ratio of 40, through two methods of impregnation of the metal: conventional and post-synthesis alumination. With the aim of determining the density of the acid sites of the Al40MCM-41 prepared by post-synthesis and conventional alumination, studies of the adsorption of n-butylamine probe molecule were carried out. Further, the studied material was characterized by thermogravimetry measurements, providing the profile of decomposition of the samples, which allowed calculation of the densities of the acid sites. The model-free kinetic algorithms were applied in order to determinate conversion and apparent activation energy. Comparison of energy-dispersive X-ray fluorescence and X-ray photoelectron spectroscopy measurements indicated that the post-synthesis method was more favourable based on the metal positioning, ‘anchored’ in the surface of the catalyst. The textural properties of the calcined Al40MCM-41 prepared by post-synthesis and conventional alumination were characterized by X-ray diffraction, N2 isothermal adsorption measurements (Brunauer– Emmett–Teller and Barrett–Joyner–Halenda), transmission electron microscopy, and X-ray photoelectron spectroscopy.
Composites from recycled polyethylene and plasma treated kapok fibers
(Springer, 2018-11-26) Ito, Edson Noriyuki; Macedo, Murilo José Pereira de; Silva, Giovanna Sabrina da; Feitor, Michelle Cequeira; Costa, Thércio Henrique de Carvalho; Melo, José Daniel Diniz
In this study, composites from recycled polyethylene and kapok fibers were prepared with fiber contents of 1, 5 and 10 wt%. Cold plasma treatment was applied to the fibers in an attempt to improve fiber/matrix adhesion. The characterization of plasma treated fibers indicated modification in chemical composition and water and oil uptake, as compared to untreated fibers. The addition of plasma treated fibers to the polymer promoted a reduction in the steady-state torque during mixing. In addition, the thermal conductivity of composites was reduced as the amount of fibers increased. Dynamic mechanical thermal analyses of composites with plasma-treated fibers indicated an increase in storage moduli, as well as an increase in glass transition temperature as compared to the pure polymer. Images of fractured surfaces show fibers well connected to the matrix suggesting good fiber/matrix adhesion. Thus, cold plasma is demonstrated as a viable non-polluting alternative to activate cellulosic fibers and improve fiber/matrix interface in polymer composites
Computer match prediction for fluorescent dyes by neural networks
(John Wiley & Sons, 2006-06-22) Bezerra, Clovis de Medeiros; Hawkyard, C. J.
Fluorescent dyes present difficulties for match prediction due to their variable excitation and emission characteristics, which depend on a variety of factors. An empirical approach is therefore favoured, such as that used in the artificial neural network method. In this paper, the production of a database with four acid dyes (two fluorescent and two non-fluorescent) is described, along with the large number of mixture dyeings that were carried out. The data were used to construct a network connecting reflectance values with concentrations in formulations. The results show that, although time consuming, this approach is viable and accurate
Cotton fabric bleached with seawater: mechanical and coloristic properties
(Scielo, 2019) Ferreira, Iêda Letícia Souza; Medeiros, José Ivan de; Steffens, Fernanda; Oliveira, Fernando Ribeiro
The textile industry needs a high volume of water to carry out its processes, which among them; textile chemical finishing is the main responsible for high water expenditure. However, nowadays there is a worldwide concern regarding the scarcity of fresh water. This research aims to study the use of seawater in the cotton bleaching process and compare the results obtained with the bleaching process made with distilled water. The characterization of the substrates was performed through the following analyses: reflectance spectrophotometry, white degree (oBerger), wettability, tensile strength, elongation, scanning electron microscopy and dispersive energy spectroscopy. The bleaching with seawater presented good whiteness index, high tensile strength values and excellent hydrophilicity, which suggest that it may be possible to perform this process in cotton fabric using seawater
Dengue: prevenção e controle pelas ondas do rádio
(2014) Almeida Júnior, José Jailson de; Oliveira, Franklin Learcton Bezerra de; Araújo, Rayane Larissa Santos de; Brilhante, Magdalena Muryelle Silva; Silva, Dany Geraldo Kramer Cavalcanti e
INTRODUÇÃO: a dengue é uma doença viral que vem tomando grandes proporções mundialmente por possuir características endêmicas e epidêmicas, se alastrando por todo o mundo e provocando grande impac-to na saúde pública. OBJETIVO: apresentar as ações desenvolvidas nas rádios AM e FM do Projeto de Extensão Vigilância Ambiental em Saúde: ações integradas de controle da dengue no município de Santa Cruz/RN. MATERIAL E MÉTODOS: trata-se de um estudo descritivo do tipo relato de experi-ências sobre ações realizadas nas emissoras de rádio AM e FM do município de Santa Cruz/RN. RESULTADOS E DISCUSSÃO: as entrevistas tiveram boa repercussão, tendo em vista o público alcançado por meio das duas emissoras. CONCLUSÃO: acredita-se que o objetivo foi atingido, considerando que o programa de rádio proporciona um contato direto com o ouvinte, o que é reforçado com os apresentadores dos programas veicu-lados pelas emissoras
Development of porous alumina membranes for treatment of textile effluent
(Taylor & Francis, 2015-02-27) Silva, Késia Karina de Oliveira Souto; Paskocimas, Carlos Alberto; Oliveira, Fernando R.; Nascimento, José Heriberto Oliveira do; Zille, Andrea
Ceramic porous membranes sintered at two different temperature using polyvinyl alcohol and ethylene glycol as binders, and composed of two types of α-alumina with different parti- cle sizes were investigated for the microfiltration of a textile effluent containing indigo dye, auxiliaries, heavy metals, oils, and solids. The physicochemical properties of the membranes and effluent were evaluated. X-ray diffraction, energy dispersive X-ray fluorescence spectros- copy, differential scanning calorimetry, and thermogravimetric analysis confirm that the thin membrane is composed of high crystalline and pure α-alumina. Scanning electron microscopy observation indicates that the membranes have smooth porous surface making it suitable for microfiltration applications. The membrane sintered at 1,450 ̊C exhibited higher water absorp- tion (WA) and apparent porosity than that sintered at 1,475 ̊C. The apparent specific gravity and flexural strength are in inverse correlation with the WA due to the enhanced densification of the membranes. The filtered effluent was evaluated using a membrane with an average pore size of 0.4 μm and a total porosity of 29.6%. The average values of rejection were 90% for color, 93% for suspended solids, 95% for turbidity, 60% for metals, and 73% for chemical oxygen demand. These results demonstrate that low-cost ceramic alumina membranes are a very promising advanced treatment for textile industrial effluents
Dyeing of cotton and polyester blended fabric previously cationized with synthetic and natural polyelectrolytes
(ELSEVIER, 2017-06) Oliveira, Fernando Ribeiro; Oliveira, Diego Alves J. de; Steffens, Fernanda; Nascimento, José Heriberto Oliveira do; Silva, Kesia Karina de Oliveira Souto; Souto, António Pedro
In this work, a plain weave composed by 50% polyester and 50% cotton (PES/CO) was functionalized by using two polyelectrolytes, in order to modify its surface to provide a dyeing with an uncommon dye class for cotton and polyester fibers. Several techniques of characterization were used to study the effects caused by the interaction between polyelectrolytes (Chitosan and PDDACl) and PES/CO fabric, such as: X-ray Photoelectronic Spectroscopy (XPS), dye solution drop absorption, Scanning Electron Microscopy (SEM) and whiteness by Berger degree. Good results of dyebath exhaustion with excellent values of color strength were obtained for the samples previously treated with PDDACl and Chitosan polyelectrolytes. These promising results mean the possibility of obtaining distinct and solid colors that cannot be obtained with the use of dispersed/reactive dyes, besides generating a lower energetic cost with the use of lower times and temperatures than those normally used to PES/CO dyeing process
Effect of Ag clusters doping on the photoluminescence, photocatalysis and magnetic properties of ZnO nanorods prepared by facile microwave-assisted hydrothermal synthesis
(Springer, 2017-04-13) Souza, Renata Priscilla de Araújo; Motta, Fabiana Vilella da; Nascimento, José Heriberto Oliveira do; Delmonte, Maurício Roberto Bomio; Borges, Filipe Martel de Magalhães; Corrêa, Marcio Assolin; Silva, Elson Longo da; Li, Maximo Siu; Bohn, Felipe; Paskocimas, Carlos Alberto
We report a chemical route to synthesize stabilized ZnO:Ag nanoparticles (NPs) combined with nanosized metallic Ag using microwave-assisted hydrothermal synthesis. We employ X-ray diffraction (XRD), field emission guns scanning electron microscopy, transmission electron microscopy, spectrophotometry, photodegradation, photoluminescence and magnetic characterizations to investigate the structural, morphological, photocatalytic and magnetic properties of ZnO:Ag samples with different Ag concentrations. We verify through XRD results the standard wurtzite crystalline phases and face-centered cubic for metallic Ag NPs. Moreover, we confirm through spectrophotometry the photocatalysis in the samples. The Ag clusters doping the pure material causes the shift from green to yellow-red, which are lower energy wavelengths, thus corroborating changes of its electrical properties due to the decreased gap. We interpret the magnetic properties in terms of the nanosizing and similar effects. Under these conditions, we show the improvement of the photocatalytic and magnetic properties of ZnO NPs
Effect of cold plasma treatment on recycled polyethylene/kapok composites interface adhesion
(Composite Interfaces, 2018-11-26) Feitor, Michele Cequeira; Macedo, Murilo José Pereira; Mattos, Adriano Lincoln Albuquerque; Costa, Thércio Henrique de Carvalho; Ito, Edson Noriyuki; Melo, José Daniel Diniz
Composites from recycled polyethylene and kapok fibers were pre- pared using untreated and plasma-treated fibers. Flow properties, mechanical properties and fracture morphology were analyzed in order to evaluate the effects of cold plasma treatment on kapok fibers to improve interfacial bonding between fibers and matrix. Melt flow rate (MFR) measurements indicated a reduction in flow rate of the polymer with the addition of kapok fibers. Storage modulus increased with fiber addition and this effect was more significant when plasma- treated fibers were used. Tanδ obtained from viscoelastic characteriza- tion also suggested improvements in fiber/matrix interface as a result of plasma treatment. Addition of kapok fibers to polyethylene pro- duced a reduction in onset decomposition temperature determined from thermogravimetry curve. However, the decrease in temperature observed does not limit composite processing. Furthermore, the degree of crystallinity of polyethylene increased with the addition of untreated fibers and reduced when plasma treated fibers were added. Morphological analysis of failure surface by Field Emission Gun Scanning Electron Microscopy (FEGSEM) suggest that fiber/matrix adhesion was clearly improved when plasma treated fibers were used. Thus, the oxygen cold plasma treatment proved to be an effec- tive non-polluting approach to enhance matrix/fiber adhesion in poly- ethylene/kapok fiber composites, as opposed to chemical treatments.
Effects of gas composition during plasma modification of polyester fabrics
(ELSEVIER, 2006) Costa, Thércio Henrique de Carvalho; Feitor, Michelle Cequeira; Alves Júnior, Clodomiro; Freire, P. B.; Bezerra, Clovis de Medeiros
In order to increase the hydrophilicities and to improve dyeability, poly(ethylene terephathalate) (polyester) fabrics were treated in low pressure and temperature plasma. Different plasma atmosphere were used in this work, leaving the gas type (oxygen, nitrogen, methane and hydrogen) as plasma variables, other parameters like pressure, exposure time, voltage and current were not variables in the process. After plasma treatment, the properties of the fabric, including surface morphology and chemical alteration, were investigated. The polyester fabrics treated with different plasma gases exhibited different morphological changes. The capillary method was applied to evaluate the improvement in water uptake of polyester fabrics, which indicated a good wettability to all atmospheres used in this work, except for a mixture containing methane, hydrogen and nitrogen
Efficient silver nanoparticles deposition method on DBD plasma-treated polyamide 6,6 for antimicrobial textiles
(IOP Publishing, 2021-04-10) Silva, Késia Karina de Oliveira Souto; Ribeiro, Ana Isabel; Senturk, Dilara; Modic, Martina; Cvelbar, Uros; Dinescu, Gheorghe; Mitu, Bogdana; Nikiforov, Anton; Leys, Christophe; Kuchakova, Irina; Vanneste, M.; Heyse, P.; Vrieze, Mike de; Souto, António P.; Zille, Andrea
Several methods for silver nanoparticles (AgNPs) deposition on dielectric barrier discharge (DBD) plasma treated and not treated polyamide 6,6 fabric were tested for the production of durable antibacterial textiles. Ultrasound-assisted, dip-coating, exhaustion at 70 ̊C and spray deposition methods were applied. The treated fabrics were analysed in terms of coating uniformity, plasma effect, nanoparticles concentration onto the fabrics and nanoparticles release. Scanning electron microscope (SEM), energy dispersive X-ray (EDX), atomic absorption spectroscopy (AAS), inductively coupled plasma optical emission spectrometry (ICP-OES) and reflectance spectroscopy(%R) were performed. In the fabrics impregnated with AgNPs by dip coating or spray methods there are no significant differences in the plasma treated and untreated samples. Ultrasound tip and exhaustion at 70 ̊C presented higher AgNPs loading. Better AgNPs distribution, higher concentration and less agglomeration were observed in the plasma treated samples and an improved controlled release as well. The plasma treated fabrics with AgNPs deposited with the ultrasound method showed the highest concentration of nanoparticles onto the fabrics as well as the lowest NPs agglomeration. However, this deposition is limited to certain areas of the fabric, the samples were not uniform. The exhaustion method showed the best equilibrium between the NPs distribution and state of agglomeration
Estudo comparativo da atuação do enfermeiro no controle de dengue e febre chikungunya
(FapUNIFESP (SciELO), 2016) Almeida Júnior, José Jailson de; Oliveira, Franklin Learcton Bezerra de; Millions, Rejane Medeiros; Costa, Marcelo Viana da; Silva, Dany Geraldo Kramer Cavalcanti e
O objetivo deste estudo foi analisar a atuação dos enfermeiros das Estratégias de Saúde da Família no controle de dengue e febre chikungunya nos municípios de Parnamirim e Santa Cruz/RN. Trata-se de um estudo exploratório, descritivo, com abordagem qualitativa de tratamento e análise de dados. A coleta foi realizada entre novembro e dezembro de 2015 por meio de uma entrevista gravada, voltada às questões que abordam a ação da enfermagem e sua equipe no controle de dengue e febre chikungunya no campo de atuação da ESF. Utilizou-se como método de observação dos dados a análise de conteúdo de Bardin. Após análise, houve criação de duas categorias – educação em saúde e campanhas pontuais. Na primeira, os entrevistados informaram realizar palestras educativas, mas não explicam a metodologia usada e nem a participação popular, como também a articulação com o setor de endemias da cidade para fortalecer a discussão. Na segunda, algumas ações são assistencialistas de caráter campanhista/higienista, realizadas pelos enfermeiros dos municípios em campanhas de “higienização” e “limpeza”, as quais se mostram bastante presentes nas falas dos entrevistados. Há uma forte presença desse modelo enraizada tanto nas ações quanto na realização de atividades educativas, usando como metodologia a palestra. Além disso, há necessidade de se realizar mais estudos que aprofundem o tema abordado, a julgar por uma amostra pequena, especialmente no município de Parnamirim
Estudo de nitretação a plasma e tratamento duplex em brocas de aço rápido
(FapUNIFESP (SciELO), 2020) Feitor, Michelle Cequeira; Serra, Petteson Linniker Carvalho; Barros Neto, João Rodrigues de; Furtado, André Sales Aguiar; Sampaio, Weslley Rick Viana; Costa, Thercio Henrique de Carvalho; Sousa, Rômulo Ribeiro Magalhães de
A nitretação a plasma é realizada em ferramentas de aços rápidos para aumentar a resistência ao desgaste da aresta de corte e reduzir a tendência do material usinado em aderir na ferramenta. O objetivo do presente trabalho é estudar a viabilidade da nitretação a plasma e do tratamento duplex em brocas de aço rápidoanalisnado o desgaste de brocas de aço rápido M2 submetidas a diferentes parâmetros de nitretação a plasma e deposição de filme de nitreto de titânio (TiN). As brocas passaram primeiro pelo tratamento de nitretação com, variando-se a temperatura em 350°C, 400°C, 450°C, 500oC e 550oC, enquanto o tratamento duplex foi dividido em nitretação convencional a 500 °C seguido de deposição de um filme fino de TiN aplicado pela técnica de deposição a plasma com gaiola catódica à temperatura de 400oC e 500 °C. As brocas nitretadas a 400°C ainda foram submetidas ao processo de deposição de um filme de TiN. Todas as brocas foram caracterizadas por microdureza Vickers e foram ensaiadas em centro de usinagem CNC, onde o corpo de prova era de aço AISI 4340. Foi realizada uma análise de desempenho entre os diferentes tratamentos, onde chegou à conclusão que o tratamento que resultou melhor desempenho na usinagem foi o tratamento de nitretação a 450°C. A camada nitretada das brocas foi analisada por perfil de microdureza, Microscopia Eletrônica de Varredura, porém observou-se que o valor de microdureza aumenta com o tempo de tratamento, e que a deposição do filme de TiN teve baixa relevância no desempenho da broca
Evaluation of aging in air of poly (ethylene terephthalat) in oxygen plasma
(Materials Research, 2015-10) Feitor, Michelle Cequeira; Alves Junior, Clodomiro; Bezerra, Clovis Medeiros; Sousa, Rômulo Ribeiro Magalhães de; Costa, Thercio Henrique de Carvalho
Polyester fabric samples – PET (poly (ethylene terephtalate)), were treated with oxygen plasma, in order to alter the hydrophilicity of such material. The process parameters: working pressure, current, tension and temperature were kept constant, varying only the treatment time. In order to evaluate the change caused on samples hydrophilicity, as well as the influence of the treatment time, the vertical wicking test was used. The samples were stored at standard temperature and pressure conditions, and their wettability were measured one day after the treatment and repeated after 30, 60 and 360 days, in order to check the stability of the effects produced. Scanning electron microscopy (SEM), Raman and ATR (Attenuated total reflection) spectroscopies were used to evaluate physical and chemical alterations on the samples surface. The results have shown a substantial improvement on the hydrophilicity of the treated samples compared to the non-treated sample.

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