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The coating of natural fiber by graphene oxide (GO) has, over, this past decade, attracted increasing attention as an effective way to improve the adhesion to polymer matrices and enhance the composite properties. In particular, the GO-functionalized 30 vol% curaua fiber (Ananas Erectifolius) reinforcing epoxy composite was found to display superior tensile and thermogravimetric properties as well as higher fiber/matrix interfacial shear strength. In this brief report, dynamic mechanical analysis (DMA) was conducted in up to 50 vol% GO-functionalized curaua fiber reinforced epoxy matrix (EM) composites. The objective was not only to extend the amount incorporated but also for the first time investigate the composite viscoelastic behavior. The GO functionalization of curaua fibers (GOCF) improved the DMA storage (E′) and loss (E″) modulus compared to the non-functionalized fiber composites. Values at 30 °C of both E′ (13.44 GPa) and E″ (0.67 GPa) for 50 vol% GO-functionalized curaua fiber reinforced epoxy matrix composites (50GOCF/EM) were substantially higher than those of 20 GOCF/EM with E′ (7.08 GPa) and E″ (0.22 GPa) as well as non-functionalized 50CF/EM with E′ (11.04 GPa) and E″ (0.45 GPa). All these results are above the neat epoxy previously reported values of E′ (3.86 GPa) and E″ (0.09 GPa). As for the tangent delta, the parameters associated with damping factor and glass transition temperature were not found to be significantly changed by GO functionalization, but decreased with respect to the neat epoxy due to chain mobility restriction.
Ulisses Costa; Lucio Nascimento; Wendell Almeida Bezerra; Vinícius De Oliveira Aguiar; Artur Pereira; Sergio Monteiro; Wagner Pinheiro. Dynamic Mechanical Behavior of Graphene Oxide Functionalized Curaua Fiber-Reinforced Epoxy Composites: A Brief Report. Polymers 2021, 13, 1897 .
AMA StyleUlisses Costa, Lucio Nascimento, Wendell Almeida Bezerra, Vinícius De Oliveira Aguiar, Artur Pereira, Sergio Monteiro, Wagner Pinheiro. Dynamic Mechanical Behavior of Graphene Oxide Functionalized Curaua Fiber-Reinforced Epoxy Composites: A Brief Report. Polymers. 2021; 13 (11):1897.
Chicago/Turabian StyleUlisses Costa; Lucio Nascimento; Wendell Almeida Bezerra; Vinícius De Oliveira Aguiar; Artur Pereira; Sergio Monteiro; Wagner Pinheiro. 2021. "Dynamic Mechanical Behavior of Graphene Oxide Functionalized Curaua Fiber-Reinforced Epoxy Composites: A Brief Report." Polymers 13, no. 11: 1897.
Graphene oxide (GO) incorporation in natural fiber composites has recently defined a novel class of materials with enhanced properties for applications, including ballistic armors. In the present work, the performance of a 0.5 vol % GO-incorporated epoxy matrix composite reinforced with 30 vol % fabric made of ramie fibers was investigated by stand-alone ballistic tests against the threat of a 0.22 lead projectile. Composite characterization was also performed by Fourier-transform infrared spectroscopy, thermal analysis and X-ray diffraction. Ballistic tests disclosed an absorbed energy of 130 J, which is higher than those reported for other natural fabrics epoxy composite, 74–97 J, as well as plain Kevlar (synthetic aramid fabric), 100 J, with the same thickness. This is attributed to the improved adhesion between the ramie fabric and the composite matrix due to the GO—incorporated epoxy. The onset of thermal degradation above 300 °C indicates a relatively higher working temperature as compared to common natural fiber polymer composites. DSC peaks show a low amount of heat absorbed or release due to glass transition endothermic (113–121 °C) and volatile release exothermic (~132 °C) events. The 1030 cm−1 prominent FTIR band, associated with GO bands between epoxy chains and graphene oxide groups, suggested an effective distribution of GO throughout the composite matrix. As expected, XRD of the 30 vol % ramie fabric-reinforced GO-incorporated epoxy matrix composite confirmed the displacement of the (0 0 1) peak of GO by 8° due to intercalation of epoxy chains into the spacing between GO layers. By improving the adhesion to the ramie fabric and enhancing the thermal stability of the epoxy matrix, as well as by superior absorption energy from projectile penetration, the GO may contribute to the composite effective ballistic performance.
Artur Camposo Pereira; Andreza Menezes Lima; Luana Cristyne Da Cruz Demosthenes; Michelle Souza Oliveira; Ulisses Oliveira Costa; Wendell Bruno Almeida Bezerra; Sergio Neves Monteiro; Ruben Jesus Sanchez Rodriguez; Janine Feitosa De Deus; Wagner Anacleto Pinheiro. Ballistic Performance of Ramie Fabric Reinforcing Graphene Oxide-Incorporated Epoxy Matrix Composite. Polymers 2020, 12, 2711 .
AMA StyleArtur Camposo Pereira, Andreza Menezes Lima, Luana Cristyne Da Cruz Demosthenes, Michelle Souza Oliveira, Ulisses Oliveira Costa, Wendell Bruno Almeida Bezerra, Sergio Neves Monteiro, Ruben Jesus Sanchez Rodriguez, Janine Feitosa De Deus, Wagner Anacleto Pinheiro. Ballistic Performance of Ramie Fabric Reinforcing Graphene Oxide-Incorporated Epoxy Matrix Composite. Polymers. 2020; 12 (11):2711.
Chicago/Turabian StyleArtur Camposo Pereira; Andreza Menezes Lima; Luana Cristyne Da Cruz Demosthenes; Michelle Souza Oliveira; Ulisses Oliveira Costa; Wendell Bruno Almeida Bezerra; Sergio Neves Monteiro; Ruben Jesus Sanchez Rodriguez; Janine Feitosa De Deus; Wagner Anacleto Pinheiro. 2020. "Ballistic Performance of Ramie Fabric Reinforcing Graphene Oxide-Incorporated Epoxy Matrix Composite." Polymers 12, no. 11: 2711.
Dye removal from manufacturing and textile industry wastewater is one of the biggest challenges in plants. The improper disposal of water with residual dyes can contaminate effluents and fresh water sources. In this work, filtration membranes based on reduced graphene oxide (rGO) were fabricated by the spray coating method, and its capability to remove dyes from water was evaluated. Graphene oxide was prepared by a modified Hummers method and posteriorly reduced with ascorbic acid; a simple and fast spray coating fabrication method was employed to produce stable membranes, which were analyzed in a home-made permeation cell. Raman spectroscopy and scanning electron microscopy (SEM) were able to prove that rGO dispersion was formed by graphene flakes with about 45.9 μm of lateral dimension; X-ray diffraction, SEM and Raman analyses indicate that the spray method was efficient in producing stable and uniform filtration membranes; and UV-vis absorption spectra of feed and permeation solution indicate that rGO membranes were capable in removing dye from water. By the main results, it is possible to affirm that rGO filtration membranes are an efficient, low-cost, scalable and fast way to remove dyes from wastewater.
Andreza Lima; Anthony Oliveira; Luana Demosthenes; Talita Sousa; Artur Pereira; Roberto Carvalho; Wagner Anacleto. Reduced Graphene Oxide Filtration Membranes for Dye Removal—Production and Characterization. Materials Proceedings 2020, 4, 29 .
AMA StyleAndreza Lima, Anthony Oliveira, Luana Demosthenes, Talita Sousa, Artur Pereira, Roberto Carvalho, Wagner Anacleto. Reduced Graphene Oxide Filtration Membranes for Dye Removal—Production and Characterization. Materials Proceedings. 2020; 4 (1):29.
Chicago/Turabian StyleAndreza Lima; Anthony Oliveira; Luana Demosthenes; Talita Sousa; Artur Pereira; Roberto Carvalho; Wagner Anacleto. 2020. "Reduced Graphene Oxide Filtration Membranes for Dye Removal—Production and Characterization." Materials Proceedings 4, no. 1: 29.
A novel class of graphene-based materials incorporated into natural lignocellulosic fiber (NLF) polymer composites is surging since 2011. The present overview is the first attempt to compile achievements regarding this novel class of composites both in terms of technical and scientific researches as well as development of innovative products. A brief description of the graphene nature and its recent isolation from graphite is initially presented together with the processing of its main derivatives. In particular, graphene-based materials, such as nanographene (NG), exfoliated graphene/graphite nanoplatelet (GNP), graphene oxide (GO) and reduced graphene oxide (rGO), as well as other carbon-based nanomaterials, such as carbon nanotube (CNT), are effectively being incorporated into NLF composites. Their disclosed superior mechanical, thermal, electrical, and ballistic properties are discussed in specific publications. Interfacial shear strength of 575 MPa and tensile strength of 379 MPa were attained in 1 wt % GO-jute fiber and 0.75 wt % jute fiber, respectively, epoxy composites. Moreover, a Young’s modulus of 44.4 GPa was reported for 0.75 wt % GO-jute fiber composite. An important point of interest concerning this incorporation is the fact that the amphiphilic character of graphene allows a better way to enhance the interfacial adhesion between hydrophilic NLF and hydrophobic polymer matrix. As indicated in this overview, two basic incorporation strategies have so far been adopted. In the first, NG, GNP, GO, rGO and CNT are used as hybrid filler together with NLF to reinforce polymer composites. The second one starts with GO or rGO as a coating to functionalize molecular bonding with NLF, which is then added into a polymeric matrix. Both strategies are contributing to develop innovative products for energy storage, drug release, biosensor, functional electronic clothes, medical implants, and armor for ballistic protection. As such, this first overview intends to provide a critical assessment of a surging class of composite materials and unveil successful development associated with graphene incorporated NLF polymer composites.
Fernanda Santos Da Luz; Fabio Da Costa Garcia Filho; Maria Teresa Gómez Del-Río; Lucio Fabio Cassiano Nascimento; Wagner Anacleto Pinheiro; Sergio Neves Monteiro. Graphene-Incorporated Natural Fiber Polymer Composites: A First Overview. Polymers 2020, 12, 1601 .
AMA StyleFernanda Santos Da Luz, Fabio Da Costa Garcia Filho, Maria Teresa Gómez Del-Río, Lucio Fabio Cassiano Nascimento, Wagner Anacleto Pinheiro, Sergio Neves Monteiro. Graphene-Incorporated Natural Fiber Polymer Composites: A First Overview. Polymers. 2020; 12 (7):1601.
Chicago/Turabian StyleFernanda Santos Da Luz; Fabio Da Costa Garcia Filho; Maria Teresa Gómez Del-Río; Lucio Fabio Cassiano Nascimento; Wagner Anacleto Pinheiro; Sergio Neves Monteiro. 2020. "Graphene-Incorporated Natural Fiber Polymer Composites: A First Overview." Polymers 12, no. 7: 1601.
Gabriel Bartholazzi; Robson Pacheco Pereira; Andreza Menezes Lima; Wagner Anacleto Pinheiro; Leila Rosa Cruz. Influence of substrate temperature on the chemical, microstructural and optical properties of spray deposited CH3NH3PbI3 perovskite thin films. Journal of Materials Research and Technology 2020, 9, 3411 -3417.
AMA StyleGabriel Bartholazzi, Robson Pacheco Pereira, Andreza Menezes Lima, Wagner Anacleto Pinheiro, Leila Rosa Cruz. Influence of substrate temperature on the chemical, microstructural and optical properties of spray deposited CH3NH3PbI3 perovskite thin films. Journal of Materials Research and Technology. 2020; 9 (3):3411-3417.
Chicago/Turabian StyleGabriel Bartholazzi; Robson Pacheco Pereira; Andreza Menezes Lima; Wagner Anacleto Pinheiro; Leila Rosa Cruz. 2020. "Influence of substrate temperature on the chemical, microstructural and optical properties of spray deposited CH3NH3PbI3 perovskite thin films." Journal of Materials Research and Technology 9, no. 3: 3411-3417.
RESUMO A técnica de deposição de filmes por spray destaca-se por sua versatilidade, simplicidade e eficiência. Neste trabalho, dois equipamentos de spray distintos foram empregados para produção de filmes de óxido de grafeno: o primeiro, um equipamento industrial para produção por método ultrassônico e o segundo, uma adaptação realizada com um aerógrafo, um solenoide, um circuito elétrico e um programa em linguagem C++, denominado de método convencional. Os filmes obtidos foram caracterizados com respeito à espessura, resistividade elétrica, transmitância e morfologia. As amostras produzidas pelo método convencional apresentaram menores espessuras e maiores transmitâncias, sendo, desse modo, mais adequadas para aplicações optoeletrônicas. Já as menores resistências de folha foram obtidas pelo método de spray ultrassônico. A morfologia dos filmes aponta melhor uniformidade para as amostras obtidas por meio da técnica ultrassônica. A análise comparativa dos resultados indicou que o equipamento convencional, apesar de ser muito mais simples e de baixo custo, foi capaz de alcançar resultados tão satisfatórios quanto os obtidos em um equipamento industrial de spray ultrassônico. A grande vantagem do equipamento industrial está na possibilidade de produção de várias amostras simultaneamente, enquanto o convencional adaptado tem como benefício a rapidez, possibilidade de deposição com folhas de óxido de grafeno maiores e acessibilidade da produção e operação do sistema.
Andreza Menezes Lima; Thebano Emílio De Almeida Santos; Rodrigo Amaral De Medeiro; Leila Rosa De Oliveira Cruz; Wagner Anacleto Pinheiro. Análise comparativa de deposições de filmes de óxido de grafeno por spray ultrassônico e convencional. Matéria (Rio de Janeiro) 2020, 25, 1 .
AMA StyleAndreza Menezes Lima, Thebano Emílio De Almeida Santos, Rodrigo Amaral De Medeiro, Leila Rosa De Oliveira Cruz, Wagner Anacleto Pinheiro. Análise comparativa de deposições de filmes de óxido de grafeno por spray ultrassônico e convencional. Matéria (Rio de Janeiro). 2020; 25 (3):1.
Chicago/Turabian StyleAndreza Menezes Lima; Thebano Emílio De Almeida Santos; Rodrigo Amaral De Medeiro; Leila Rosa De Oliveira Cruz; Wagner Anacleto Pinheiro. 2020. "Análise comparativa de deposições de filmes de óxido de grafeno por spray ultrassônico e convencional." Matéria (Rio de Janeiro) 25, no. 3: 1.
Composites with sustainable natural fibers are currently experiencing remarkably diversified applications, including in engineering industries, owing to their lower cost and density as well as ease in processing. Among the natural fibers, the fiber extracted from the leaves of the Amazonian curaua plant (Ananas erectifolius) is a promising strong candidate to replace synthetic fibers, such as aramid (Kevlar™), in multilayered armor system (MAS) intended for ballistic protection against level III high velocity ammunition. Another remarkable material, the graphene oxide is attracting considerable attention for its properties, especially as coating to improve the interfacial adhesion in polymer composites. Thus, the present work investigates the performance of graphene oxide coated curaua fiber (GOCF) reinforced epoxy composite, as a front ceramic MAS second layer in ballistic test against level III 7.62 mm ammunition. Not only GOCF composite with 30 vol% fibers attended the standard ballistic requirement with 27.4 ± 0.3 mm of indentation comparable performance to Kevlar™ 24 ± 7 mm with same thickness, but also remained intact, which was not the case of non-coated curaua fiber similar composite. Mechanisms of ceramic fragments capture, curaua fibrils separation, curaua fiber pullout, composite delamination, curaua fiber braking, and epoxy matrix rupture were for the first time discussed as a favorable combination in a MAS second layer to effectively dissipate the projectile impact energy.
Ulisses Oliveira Costa; Lucio Fabio Cassiano Nascimento; Julianna Magalhães Garcia; Sergio Monteiro; Fernanda Santos Da Luz; Wagner Anacleto Pinheiro; Fabio Da Costa Garcia Filho. Effect of Graphene Oxide Coating on Natural Fiber Composite for Multilayered Ballistic Armor. Polymers 2019, 11, 1356 .
AMA StyleUlisses Oliveira Costa, Lucio Fabio Cassiano Nascimento, Julianna Magalhães Garcia, Sergio Monteiro, Fernanda Santos Da Luz, Wagner Anacleto Pinheiro, Fabio Da Costa Garcia Filho. Effect of Graphene Oxide Coating on Natural Fiber Composite for Multilayered Ballistic Armor. Polymers. 2019; 11 (8):1356.
Chicago/Turabian StyleUlisses Oliveira Costa; Lucio Fabio Cassiano Nascimento; Julianna Magalhães Garcia; Sergio Monteiro; Fernanda Santos Da Luz; Wagner Anacleto Pinheiro; Fabio Da Costa Garcia Filho. 2019. "Effect of Graphene Oxide Coating on Natural Fiber Composite for Multilayered Ballistic Armor." Polymers 11, no. 8: 1356.
A recent strategy that has emerged for the design of increasingly functional hydrogels is the incorporation of nanofillers in order to exploit their specific properties to either modify the performance of the hydrogel or add functionality. The emergence of carbon nanomaterials in particular has provided great opportunity for the use of graphene derivatives (GDs) in biomedical applications. The key challenge when designing hybrid materials is the understanding of the molecular interactions between the matrix (peptide nanofibers) and the nanofiller (here GDs) and how these affect the final properties of the bulk material. For the purpose of this work, three gelling β-sheet-forming, self-assembling peptides with varying physiochemical properties and five GDs with varying surface chemistries were chosen to formulate novel hybrid hydrogels. First the peptide hydrogels and the GDs were characterized; subsequently, the molecular interaction between peptides nanofibers and GDs were probed before formulating and mechanically characterizing the hybrid hydrogels. We show how the interplay between electrostatic interactions, which can be attractive or repulsive, and hydrophobic (and π–π in the case of peptide containing phenylalanine) interactions, which are always attractive, play a key role on the final properties of the hybrid hydrogels. The shear modulus of the hydrid hydrogels is shown to be related to the strength of fiber adhesion to the flakes, the overall hydrophobicity of the peptides, as well as the type of fibrillar network formed. Finally, the cytotoxicity of the hybrid hydrogel formed at pH 6 was also investigated by encapsulating and culturing human mesemchymal stem cells (hMSC) over 14 days. This work clearly shows how interactions between peptides and GDs can be used to tailor the mechanical properties of the resulting hydrogels, allowing the incorporation of GD nanofillers in a controlled way and opening the possibility to exploit their intrinsic properties to design novel hybrid peptide hydrogels for biomedical applications.
Jacek K. Wychowaniec; Maria Iliut; Mi Zhou; Jonathan Moffat; Mohamed Elsawy; Wagner Anacleto Pinheiro; Judith A. Hoyland; Aline F. Miller; Aravind Vijayaraghavan; Alberto Saiani. Designing Peptide/Graphene Hybrid Hydrogels through Fine-Tuning of Molecular Interactions. Biomacromolecules 2018, 19, 2731 -2741.
AMA StyleJacek K. Wychowaniec, Maria Iliut, Mi Zhou, Jonathan Moffat, Mohamed Elsawy, Wagner Anacleto Pinheiro, Judith A. Hoyland, Aline F. Miller, Aravind Vijayaraghavan, Alberto Saiani. Designing Peptide/Graphene Hybrid Hydrogels through Fine-Tuning of Molecular Interactions. Biomacromolecules. 2018; 19 (7):2731-2741.
Chicago/Turabian StyleJacek K. Wychowaniec; Maria Iliut; Mi Zhou; Jonathan Moffat; Mohamed Elsawy; Wagner Anacleto Pinheiro; Judith A. Hoyland; Aline F. Miller; Aravind Vijayaraghavan; Alberto Saiani. 2018. "Designing Peptide/Graphene Hybrid Hydrogels through Fine-Tuning of Molecular Interactions." Biomacromolecules 19, no. 7: 2731-2741.
RESUMO Dispersões de óxido de grafeno (GO) e de óxido de grafeno reduzido (rGO) foram produzidas, respectivamente, por via química através do método de Hummers modificado e por redução do GO com adição de polímero PSS (poli (4-estirenosulfonato de sódio)) e ácido ascórbico. Amostras de GO e rGO/PSS foram caracterizadas pelas seguintes técnicas: microscopia óptica, microscopia eletrônica de varredura (MEV), espectroscopia Raman e espectroscopia de fotoelétrons excitados por raios X (XPS). A partir das dispersões foram depositados filmes finos em substratos de vidro pelos seguintes métodos: spray, dip coating e spin coating. Os filmes produzidos foram, em seguida, tratados termicamente para melhoria da aderência nos substratos e, especificamente para os filmes de GO, para redução, de modo a formar o óxido de grafeno reduzido termicamente (trGO). Os filmes foram caracterizados quanto a espessura, morfologia, transmitância e resistência de folha. Por meio das caracterizações realizadas a partir das dispersões foi possível observar folhas de grafeno pela microscopia óptica, indicando o sucesso do método de produção empregado; por meio do XPS, determinou-se a composição das amostras de GO e rGO e confirmou-se que a redução com ácido ascórbico foi efetiva; as transmitâncias obtidas mostraram-se dentro da faixa indicada para aplicação e as resistividades de algumas amostras, alcançaram valores próximos a de materiais tradicionalmente aplicados como filmes transparentes e condutores.
Andreza Menezes Lima; Géssica Seara Faria; Stefania Nardecchia; Leila Rosa De Oliveira Cruz; Mariana De Mattos Vieira Mello Souza; Wagner Anacleto Pinheiro. Produção e caracterização de filmes finos transparentes e condutores de óxido de grafeno reduzido. Matéria (Rio de Janeiro) 2018, 22, 1 .
AMA StyleAndreza Menezes Lima, Géssica Seara Faria, Stefania Nardecchia, Leila Rosa De Oliveira Cruz, Mariana De Mattos Vieira Mello Souza, Wagner Anacleto Pinheiro. Produção e caracterização de filmes finos transparentes e condutores de óxido de grafeno reduzido. Matéria (Rio de Janeiro). 2018; 22 (suppl 1):1.
Chicago/Turabian StyleAndreza Menezes Lima; Géssica Seara Faria; Stefania Nardecchia; Leila Rosa De Oliveira Cruz; Mariana De Mattos Vieira Mello Souza; Wagner Anacleto Pinheiro. 2018. "Produção e caracterização de filmes finos transparentes e condutores de óxido de grafeno reduzido." Matéria (Rio de Janeiro) 22, no. suppl 1: 1.
RESUMO Neste trabalho foram preparadas dispersões aquosas de óxido de grafeno (GO) e óxido de grafeno reduzido (rGO), em diferentes tempos de oxidação, com o objetivo de verificar a influência do tempo de oxidação em relação às características das folhas (flakes) finais. As dispersões de GO foram preparadas pelo método de Hummers modificado utilizando os seguintes tempos de oxidação: 4 h; 1 dia; 3 dias; 7 dias e 10 dias. Em seguida, as dispersões de GO foram submetidas ao tratamento de redução com ácido ascórbico, obtendo-se o rGO. As caracterizações das amostras foram realizadas por meio das análises de espectroscopia Raman, espectroscopia de fotoelétrons excitados por raios X (XPS), microscopia eletrônica de varredura (MEV) e difração de raios X (DRX). A espectroscopia Raman mostrou a variação da relação de intensidade entre as bandas D e G (ID/IG) à medida que o tempo de oxidação foi aumentado. A análise de XPS exibiu a alteração dos percentuais de carbono (C) e oxigênio (O). Através de análise no MEV foi correlacionada a morfologia dos flakes com o aumento do tempo de oxidação. E por fim, com o auxílio de DRX, foi verificada a variação da distância interplanar.
Géssica Seara Faria; Andreza Menezes Lima; Luiz Paulo Brandão; Alberto Pessoa Da Costa; Stefania Nardecchia; Alexandre Antunes Ribeiro; Wagner Anacleto Pinheiro. Produção e caracterização de óxido de grafeno e óxido de grafeno reduzido com diferentes tempos de oxidação. Matéria (Rio de Janeiro) 2018, 22, 1 .
AMA StyleGéssica Seara Faria, Andreza Menezes Lima, Luiz Paulo Brandão, Alberto Pessoa Da Costa, Stefania Nardecchia, Alexandre Antunes Ribeiro, Wagner Anacleto Pinheiro. Produção e caracterização de óxido de grafeno e óxido de grafeno reduzido com diferentes tempos de oxidação. Matéria (Rio de Janeiro). 2018; 22 (suppl 1):1.
Chicago/Turabian StyleGéssica Seara Faria; Andreza Menezes Lima; Luiz Paulo Brandão; Alberto Pessoa Da Costa; Stefania Nardecchia; Alexandre Antunes Ribeiro; Wagner Anacleto Pinheiro. 2018. "Produção e caracterização de óxido de grafeno e óxido de grafeno reduzido com diferentes tempos de oxidação." Matéria (Rio de Janeiro) 22, no. suppl 1: 1.
RESUMO A energia solar fotovoltaica é atualmente um mercado consolidado. Entre 2010-2016, a taxa de crescimento global de instalações fotovoltaicas foi de 40%, um crescimento dificilmente alcançado por outros segmentos da indústria tecnológica. Células solares de silício responderam por 94% do mercado em 2016, enquanto a parcela referente aos filmes finos foi de 6%. Um dos materiais empregados no segmento fotovoltaico de filmes finos é o disseleneto de cobre índio e gálio (CIGS). Este trabalho apresenta os primeiros resultados de um programa colaborativo entre o Instituto Militar de Engenharia e o Florida Solar Energy Center, que visa à fabricação de células fotovoltaicas de CIGS. Os dispositivos com a configuração vidro/Mo/CIGS/CdS/ZnO/ZnO:Al/metal foram fabricados no Florida Solar Energy Center e caracterizados no Instituto Militar de Engenharia, a partir das medidas de resposta espectral e dos parâmetros fotovoltaicos extraídos das curvas corrente-tensão. A maior eficiência alcançada foi 3,8%. Os resultados mostraram que a eficiência foi basicamente limitada pelo fator de forma e pela tensão de circuito aberto. Resistências em série e paralelo foram responsáveis pelo baixo valor de FF, enquanto que a ausência do tratamento pós-deposição na presença de metais alcalinos e a quantidade de gálio insuficiente foi responsável pelo baixo Voc. Os resultados também sugerem variações na espessura da camada de CdS, causadas provavelmente pela agitação excessiva da solução precursora durante a deposição por banho químico.
Renan De Melo Correia Lima; Rodrigo Amaral De Medeiro; Matheus Garcia Fonseca; Neelkanth Gurupad Dhere; Onkar Shinde; Eric Schneller; Wagner Anacleto Pinheiro; Carlos Luiz Ferreira; Leila Rosa Cruz. Caracterização de células solares de filmes finos de CIGS. Matéria (Rio de Janeiro) 2018, 22, 1 .
AMA StyleRenan De Melo Correia Lima, Rodrigo Amaral De Medeiro, Matheus Garcia Fonseca, Neelkanth Gurupad Dhere, Onkar Shinde, Eric Schneller, Wagner Anacleto Pinheiro, Carlos Luiz Ferreira, Leila Rosa Cruz. Caracterização de células solares de filmes finos de CIGS. Matéria (Rio de Janeiro). 2018; 22 (suppl 1):1.
Chicago/Turabian StyleRenan De Melo Correia Lima; Rodrigo Amaral De Medeiro; Matheus Garcia Fonseca; Neelkanth Gurupad Dhere; Onkar Shinde; Eric Schneller; Wagner Anacleto Pinheiro; Carlos Luiz Ferreira; Leila Rosa Cruz. 2018. "Caracterização de células solares de filmes finos de CIGS." Matéria (Rio de Janeiro) 22, no. suppl 1: 1.
No presente artigo so apresentados e discutidos resultados relativos influncia da temperatura de reduo em filmes depositados por spray de xido de grafeno (GO) e de xido de grafeno reduzido quimicamente (rGO). O aumento da temperatura resultou em um maior grau de empolamento dos filmes de GO comparativamente aos de rGO, principalmente em temperaturas mais elevadas, devido decomposio de grupos funcionais. Contudo, esse mesmo aumento da temperatura tambm resultou em uma diminuio da resistncia eltrica dos filmes. Assim, buscou-se determinar uma temperatura em que houvesse menor grau de empolamento e resistncia eltrica, a fim de produzir contatos eltricos traseiros adequados para clulas solares.
Andreza Menezes Lima; Géssica Seara Faria; Rodrigo Amaral De Medeiro; Leila Rosa De Oliveira Cruz Cruz; Wagner Anacleto Pinheiro. INFLUÊNCIA DA TEMPERATURA DE REDUÇÃO EM FILMES DE ÓXIDO DE GRAFENO REDUZIDO PARA CONTATOS ELÉTRICOS EM CÉLULAS SOLARES. Semioses 2017, 11, 1 .
AMA StyleAndreza Menezes Lima, Géssica Seara Faria, Rodrigo Amaral De Medeiro, Leila Rosa De Oliveira Cruz Cruz, Wagner Anacleto Pinheiro. INFLUÊNCIA DA TEMPERATURA DE REDUÇÃO EM FILMES DE ÓXIDO DE GRAFENO REDUZIDO PARA CONTATOS ELÉTRICOS EM CÉLULAS SOLARES. Semioses. 2017; 11 (4):1.
Chicago/Turabian StyleAndreza Menezes Lima; Géssica Seara Faria; Rodrigo Amaral De Medeiro; Leila Rosa De Oliveira Cruz Cruz; Wagner Anacleto Pinheiro. 2017. "INFLUÊNCIA DA TEMPERATURA DE REDUÇÃO EM FILMES DE ÓXIDO DE GRAFENO REDUZIDO PARA CONTATOS ELÉTRICOS EM CÉLULAS SOLARES." Semioses 11, no. 4: 1.
Stainless steels are well known by their corrosion resistance. The austenitic types, in particular, are also applied as structural components in engineering systems operating at high temperatures such as nuclear reactors, petrochemical furnaces and turbines. For these applications operational temperatures may go up to 800ºC. Under constant load applications the main mechanism of failure, which would limit the material's life, is creep. In the present work creep parameters were evaluated in the high temperature interval of 600 to 800ºC for an AISI 316 austenitic stainless steel. Dislocation substructures were observed by transmission electron microscopy in creep ruptured specimens. Two distinct mechanisms of dynamic strain aging and dynamic recovery associated with different values for the power law exponent n and the Arrhenius activation energy Q for creep were verified below and above 700ºC, respectively. Keywords: Creep test; AISI 316 stainless steel; dislocation substructure; high temperature mechanisms
Sergio Monteiro; Fernanda Santos Da Luz; Wagner Anacleto Pinheiro; Luiz Paulo Mendonça Brandão; Fábio De Oliveira Braga; Foluke Salgado De Assis. Creep Parameters and Dislocation Substructure in AISI 316 Austenitic Stainless Steel From 600ºC to 800ºC. Materials Research 2017, 20, 231 -235.
AMA StyleSergio Monteiro, Fernanda Santos Da Luz, Wagner Anacleto Pinheiro, Luiz Paulo Mendonça Brandão, Fábio De Oliveira Braga, Foluke Salgado De Assis. Creep Parameters and Dislocation Substructure in AISI 316 Austenitic Stainless Steel From 600ºC to 800ºC. Materials Research. 2017; 20 (suppl 2):231-235.
Chicago/Turabian StyleSergio Monteiro; Fernanda Santos Da Luz; Wagner Anacleto Pinheiro; Luiz Paulo Mendonça Brandão; Fábio De Oliveira Braga; Foluke Salgado De Assis. 2017. "Creep Parameters and Dislocation Substructure in AISI 316 Austenitic Stainless Steel From 600ºC to 800ºC." Materials Research 20, no. suppl 2: 231-235.
The performance of a novel multilayered armor in which the commonly used plies of aramid fabric layer were replaced by an equal thickness layer of distinct curaua fiber-reinforced composites with epoxy or polyester matrices was assessed. The investigated armor, in addition to its polymeric layer (aramid fabric or curaua composite), was also composed of a front Al2O3 ceramic tile and backed by an aluminum alloy sheet. Ballistic impact tests were performed with actual 7.62 caliber ammunitions. Indentation in a clay witness, simulating human body behind the back layer, attested the efficacy of the curaua-reinforced composite as an armor component. The conventional aramid fabric display a similar indentation as the curaua/polyester composite but was less efficient (deeper indentation) than the curaua/epoxy composite. This advantage is shown to be significant, especially in favor of the lighter and cheaper epoxy composite reinforced with 30 vol pct of curaua fiber, as possible substitute for aramid fabric in multilayered ballistic armor for individual protection. Scanning electron microscopy revealed the mechanism associated with the curaua composite ballistic performance.
Sergio Neves Monteiro; Luis Henrique Leme Louro; Willian Trindade; Carlos Elias; Carlos Luiz Ferreira; Eduardo De Sousa Lima; Ricardo Weber; João Carlos Miguez Suarez; André Figueiredo; Wagner Anacleto Pinheiro; Luís Carlos da Silva; Édio Pereira Lima. Natural Curaua Fiber-Reinforced Composites in Multilayered Ballistic Armor. Metallurgical and Materials Transactions B 2015, 46, 4567 -4577.
AMA StyleSergio Neves Monteiro, Luis Henrique Leme Louro, Willian Trindade, Carlos Elias, Carlos Luiz Ferreira, Eduardo De Sousa Lima, Ricardo Weber, João Carlos Miguez Suarez, André Figueiredo, Wagner Anacleto Pinheiro, Luís Carlos da Silva, Édio Pereira Lima. Natural Curaua Fiber-Reinforced Composites in Multilayered Ballistic Armor. Metallurgical and Materials Transactions B. 2015; 46 (10):4567-4577.
Chicago/Turabian StyleSergio Neves Monteiro; Luis Henrique Leme Louro; Willian Trindade; Carlos Elias; Carlos Luiz Ferreira; Eduardo De Sousa Lima; Ricardo Weber; João Carlos Miguez Suarez; André Figueiredo; Wagner Anacleto Pinheiro; Luís Carlos da Silva; Édio Pereira Lima. 2015. "Natural Curaua Fiber-Reinforced Composites in Multilayered Ballistic Armor." Metallurgical and Materials Transactions B 46, no. 10: 4567-4577.
Leila Rosa Cruz; José Antônio Sousa Fernandes; Carlos Luiz Ferreira; Wagner Anacleto Pinheiro. Microstructural and optical properties of CSS and CBD-CdS thin films for photovoltaic solar cells. Matéria (Rio de Janeiro) 2014, 19, 228 -234.
AMA StyleLeila Rosa Cruz, José Antônio Sousa Fernandes, Carlos Luiz Ferreira, Wagner Anacleto Pinheiro. Microstructural and optical properties of CSS and CBD-CdS thin films for photovoltaic solar cells. Matéria (Rio de Janeiro). 2014; 19 (3):228-234.
Chicago/Turabian StyleLeila Rosa Cruz; José Antônio Sousa Fernandes; Carlos Luiz Ferreira; Wagner Anacleto Pinheiro. 2014. "Microstructural and optical properties of CSS and CBD-CdS thin films for photovoltaic solar cells." Matéria (Rio de Janeiro) 19, no. 3: 228-234.
CdS/CdTe photovoltaic cells were grown in a homemade close-spaced sublimation equipment where all steps of cell fabrication are carried out continuously, without breaking the vacuum. The best efficiency achieved was 7%. Some devices partially prepared in this system were finished (heat treatment and back contact processing) at the National Renewable Energy Laboratory and showed efficiencies in the range of 10–11%, due to higher values of fill factor and photocurrent. Comparison between the procedures followed in the two laboratories identified some critical issues in the CSS process carried out continuously, such as the temperature of the heat treatment and the nature of the back contact.
L.R. Cruz; W.A. Pinheiro; R.A. Medeiro; C.L. Ferreira; R.G. Dhere; J.N. Duenow. Influence of heat treatment and back contact processing on the performance of CdS/CdTe thin film solar cells produced in a CSS in-line system. Vacuum 2012, 87, 45 -49.
AMA StyleL.R. Cruz, W.A. Pinheiro, R.A. Medeiro, C.L. Ferreira, R.G. Dhere, J.N. Duenow. Influence of heat treatment and back contact processing on the performance of CdS/CdTe thin film solar cells produced in a CSS in-line system. Vacuum. 2012; 87 ():45-49.
Chicago/Turabian StyleL.R. Cruz; W.A. Pinheiro; R.A. Medeiro; C.L. Ferreira; R.G. Dhere; J.N. Duenow. 2012. "Influence of heat treatment and back contact processing on the performance of CdS/CdTe thin film solar cells produced in a CSS in-line system." Vacuum 87, no. : 45-49.
This work involved the construction of an in-line system, where CdS and CdTe depositions, CdCl 2 vapor treatment and ZnTe deposition were performed by close-spaced sublimation technique without the necessity of opening the system. The system allowed easy movement by rotating the substrate to the deposition regions. The time spent to produce solar cells in the new system (up to 120 min) was considerably shorter than those achieved in other works to perform similar steps with vacuum break. The new system allowed the substrate was positioned in the deposition region after the source and substrate graphite blocks were already heated, resulting in a high initial nucleation rate and the production of dense and continuous films, suitable for production of high efficiency cells. The first cells, with an area of 1 cm 2 , showed efficiencies up to 7%.
W. A. Pinheiro; A. R. S. Goncalves; L. R. Cruz; C. L. Ferreira. Construction of an in-line system to produce CdS/CdTe solar cells. 2011 37th IEEE Photovoltaic Specialists Conference 2011, 002804 -002807.
AMA StyleW. A. Pinheiro, A. R. S. Goncalves, L. R. Cruz, C. L. Ferreira. Construction of an in-line system to produce CdS/CdTe solar cells. 2011 37th IEEE Photovoltaic Specialists Conference. 2011; ():002804-002807.
Chicago/Turabian StyleW. A. Pinheiro; A. R. S. Goncalves; L. R. Cruz; C. L. Ferreira. 2011. "Construction of an in-line system to produce CdS/CdTe solar cells." 2011 37th IEEE Photovoltaic Specialists Conference , no. : 002804-002807.
This work shows results for CdS/CdTe photovoltaic cells grown in a homemade in-line close-spaced sublimation equipment. In this system, most of the steps of cell fabrication were carried out continuously, using dry processing, without breaking vacuum. The efficiency values ranged from 3.5 to 7%. These cells were compared with unfinished devices prepared in the in-line system and finished (heat treatment and contact processing) at NREL. The results suggested that some steps in the cell fabrication should be optimized.
L. R. Cruz; W. A. Pinheiro; C. L. Ferreira; J. N. Duenow; R. G. Dhere. Thin film CdS/CdTe solar cells produced in a CSS in-line system. 2011 37th IEEE Photovoltaic Specialists Conference 2011, 002705 -002708.
AMA StyleL. R. Cruz, W. A. Pinheiro, C. L. Ferreira, J. N. Duenow, R. G. Dhere. Thin film CdS/CdTe solar cells produced in a CSS in-line system. 2011 37th IEEE Photovoltaic Specialists Conference. 2011; ():002705-002708.
Chicago/Turabian StyleL. R. Cruz; W. A. Pinheiro; C. L. Ferreira; J. N. Duenow; R. G. Dhere. 2011. "Thin film CdS/CdTe solar cells produced in a CSS in-line system." 2011 37th IEEE Photovoltaic Specialists Conference , no. : 002705-002708.
O objetivo deste trabalho é descrever alterações microestruturais e físicas em filmes finos de sulfeto de cádmio (CdS), decorrentes de um tratamento térmico conduzido em presença de cloreto de cádmio (CdCl2). Para isso, um filme de CdCl2 foi depositado sobre a superfície dos filmes de CdS antes do tratamento. A deposição do filme de CdCl2 e o tratamento térmico foram realizados em um sistema de sublimação em espaço reduzido (CSS). Observou-se que o tratamento conduzido em temperaturas acima de 400 ºC favorece a cristalização dos filmes de CdS. Mudanças na energia de banda proibida dos filmes tratados foram observadas, as quais foram atribuídas a modificações na estrutura cristalina das amostras.
G. D. Caboclo; J. A. S. Fernandes; W. A. Pinheiro; L. R. Cruz. Alterações microestruturais e físicas em filmes de CdS submetidos a tratamento térmico em presença de CdCl2. Matéria (Rio de Janeiro) 2011, 16, 606 -612.
AMA StyleG. D. Caboclo, J. A. S. Fernandes, W. A. Pinheiro, L. R. Cruz. Alterações microestruturais e físicas em filmes de CdS submetidos a tratamento térmico em presença de CdCl2. Matéria (Rio de Janeiro). 2011; 16 (1):606-612.
Chicago/Turabian StyleG. D. Caboclo; J. A. S. Fernandes; W. A. Pinheiro; L. R. Cruz. 2011. "Alterações microestruturais e físicas em filmes de CdS submetidos a tratamento térmico em presença de CdCl2." Matéria (Rio de Janeiro) 16, no. 1: 606-612.
In this work CdS/CdTe solar cells were submitted to solution, sublimation and vapor CdCl 2 treatments, followed by NP etch for several periods of time. The influence of these procedures on cell efficiency is discussed. The individual layers are analyzed and the results are compared with similar studies in the literature. The best NP etching time was 20 s for all CdCl 2 treatments. The highest efficiency was achieved for the cell submitted to the solution treatment at 380 °C. Although the layers have shown good properties for a high efficiency cell, the maximum overall efficiency was only 7.8%, probably due to high series and low shunt resistances.
W.A. Pinheiro; J.A.S. Fernandes; G.D. Caboclo; B. To; C.L. Ferreira; João Roberto Toledo Quadros; L.R. Cruz. Fabrication of TCO/CdS/CdTe/Au solar cells using different CdCl2 treatments. 2008 33rd IEEE Photovolatic Specialists Conference 2008, 1 -4.
AMA StyleW.A. Pinheiro, J.A.S. Fernandes, G.D. Caboclo, B. To, C.L. Ferreira, João Roberto Toledo Quadros, L.R. Cruz. Fabrication of TCO/CdS/CdTe/Au solar cells using different CdCl2 treatments. 2008 33rd IEEE Photovolatic Specialists Conference. 2008; ():1-4.
Chicago/Turabian StyleW.A. Pinheiro; J.A.S. Fernandes; G.D. Caboclo; B. To; C.L. Ferreira; João Roberto Toledo Quadros; L.R. Cruz. 2008. "Fabrication of TCO/CdS/CdTe/Au solar cells using different CdCl2 treatments." 2008 33rd IEEE Photovolatic Specialists Conference , no. : 1-4.