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- Avaliação da resistência à exposição atmosférica de madeiras termo-modificadasPublication . Godinho, Delfina; Araújo, Solange; Paiva Luís, Teresa; Ferreira, Cristina; Quilhó, Teresa; Gominho, Jorge; Cunha Diamantino, TeresaRESUMO: Em sentido lato pode-se afirmar que a madeira sofre biocorrosão, o que constitui um fator limitante para a sua aplicação no exterior, caso não haja uma proteção adequada. A termo-modifcação é um dos métodos utilizados para aumentar a durabilidade da madeira. Uma das vantagens deste processo é que não requer qualquer tipo de adição de químicos. A temperatura utilizada no processo induz a alterações químicas dos constituintes da matriz celular que promovem o aumento da durabilidade aos agentes bióticos e abióticos, mas também provoca alterações nas propriedades mecânicas, nomeadamente a diminuição do módulo de elasticidade (MOE) e de rotura (MOR). O presente trabalho teve como objetivo a avaliação da durabilidade da madeira termo-modificada de 3 espécies: o pinheiro-bravo (Pinus pinaster), a principal espécie utilizada pela indústria portuguesa de madeira sólida, a acácia (Acacia melanoxylon) e o freixo (Fraxinus excelsior). Amostras destas madeiras termomodificadas foram depois, expostas durante 2 anos em duas estações de ensaio representativas de dois ambientes diferentes, no Lumiar (ambiente urbano) e em Sines (ambiente marítimo/industrial). A avaliação da resistência da madeira à exposição atmosférica, incluiu a recolha de amostras ao longo de 24 meses de exposição e a análise das superfícies das amostras por espetroscopia de infravermelho com transformada de Fourier (FTIR) com acessório de refletância total atenuada (ATR) e por microscopia eletrónica de varrimento (SEM) com um espectrómetro de raios X de energia dispersiva (EDS) associado. Os resultados preliminares indicam um comportamento semelhante para todas as madeiras expostas em ambas as estações. Verificou-se, contudo, que embora se tivesse observado o aparecimento de fendas e de inúmeras partículas na superfície de todas as madeiras, houve uma maior incidência nas expostas em Sines (zona com maiores variações de humidade e temperatura), nomeadamente nas amostras de 9 meses, onde se observaram na superfície cristais de NaCl, devido à proximidade desta estação da orla marítima. Os espetros de FTIR-ATR indicam ter ocorrido diminuição do teor em hemiceluloses e de lenhina na superfície das amostras principalmente nas amostras recolhidas após os 24 meses de exposição, tanto em Sines como no Lumiar.
- Corrosion and anticorrosive protection by painting of aluminum rolling stockPublication . Rosa, Teresa; Marques, Maria João; Gonçalves, Rita; Carvalho, Francisco; Leal, Cristóvão Francisco; Ferreira, Cristina; Cunha Diamantino, TeresaABSTRACT: Due to its characteristics, aluminum and its alloys have been widely used in the manufacture of high-speed rolling stock. The series 4000 (Alfa Pendular service), manufactured by Fiat Ferroviaria (current Alstom), have aluminum alloy case structure, highlighting the 6082 alloy due to its good formability, with applications at structure level [1]. In operation since 1999, they are subjected to reactive maintenance and planned maintenance. Regarding maintenance related to the corrosion protection of structures, it is of particular importance to develop an appropriate specification and ensure that all tasks, with particular emphasis on those associated with surface preparation and corrosion protection by painting, are performed in accordance with improved practices to ensure longer service life. In addition to the conditions inherent to the service, the vandalism to which the material is subjected, foreign bodies that cause mechanical damages, various atmospheric conditions with environments of different categories of corrosivity, as well as accumulation of water/condensates or cleaning products/graffiti removers, are factors that contribute to the degradation of the material.
- eMaPriCe - Estudo de Matérias-Primas Críticas e estratégicas e economia circular em PortugalPublication . Simoes, Sofia; Sousa Rocha, Cristina; Alexandre, Jorge; Catarino, Justina; Ferreira, Cristina; Oliveira, Paula; Amorim, Filipa; Niza, Samuel; Nogueira, CarlosRESUMO: O eMaPriCe tem por objetivo identificar oportunidades de implementação de estratégias de Economia Circular (EC), a fim de evitar que as Matérias-Primas Críticas (MPC) se transformem em resíduos, bem como opções da substituição destas por matérias-primas não críticas. Este estudo pretende também apresentar estratégias de recuperação das MPC presentes nos resíduos, dando assim resposta à Diretiva-Quadro Resíduos. O estudo focou-se nas 30 MPC na lista Europeia, bem como a cortiça natural, uma matéria-prima estratégica para Portugal, visto ser o seu maior produtor mundial. Estas 31 matérias-primas são designadas como MPC+. Foi feito uma identificação das aplicações na economia Portuguesa das MPC+ para os setores Têxteis e calçado; Cerâmica; Cortiça; Exploração mineira; Químicos e fertilizantes; Equipamentos elétricos e eletrónicos (EEE); Energias renováveis e Automóvel. Todas as MPC na lista europeia são utilizadas em Portugal para os setores considerados. O setor com maior diversidade na utilização de MPC+ é o setor dos EEE (26 MPC+), seguindo-se os setores químico e automóvel (24 MPC+ cada), e os têxteis (21 MPC+). As energias renováveis e cerâmica utilizam 14 e 13 MPC+, respetivamente, enquanto o calçado utiliza 11 MPC+. Por fim, tanto o setor da cortiça como da exploração mineira recorrem a apenas 2 MPC+ cada.
- The influence of climatic parameters on wood durability : a review [Resumo]Publication . Godinho, Delfina; Ferreira, Cristina; Paiva Luís, Teresa; Alves, José António; Loureiro, David; Cunha Diamantino, Teresa
- Aging of elastomeric components of a solar thermal collector under solar radiationPublication . Ferreira, Cristina; Ritto, G.; Cidade, M. T.; Carvalho, Maria João; Cunha Diamantino, TeresaABSTRACT: Elastomeric components play important functions in solar thermal collectors (STC’s) as sealings, fittings or absorbers, being important that they maintain their performance along STC lifetime. However, stress factors such as high temperatures and high levels of solar radiation, as exist in southern Europe countries, can affect the properties of those components. A testing programme for the assessment of elastomeric materials of such components is detailed in international standards (ISO 9808 and ISO 9553), which already considers the effect of heating.
- Accelerated aging tests for solar absorber coatingsPublication . Cunha Diamantino, Teresa; Gonçalves, Rita; Páscoa, Soraia; Alves, Isabel Nascimento; Chambino, Teresa; Ferreira, Cristina; Carvalho, Maria JoãoABSTRACT: The need of a higher role of solar energy within the energy mix in the coming decades obliges the systems to increase their performance and reliability. It is demanded that the solar absorbers, as the key component of solar thermal systems, should be low cost with high efficiency for extended lifetimes under different kinds of environments. Commercially, there are two different types of solutions as selective solar absorbers coatings: coatings obtained by physical vapor deposition (PVD) and by paint coatings (PC). These coatings present different physical and chemical characteristics. Therefore, it is important to know how these coatings degrade over time in different environments. Results obtained with two different PVD coatings and three PC, under different accelerated aging tests, are presented. The aging tests performed included different environmental stress corrosion conditions: temperature, humidity, chlorides, sulphur dioxide and nitrogen oxides. Cyclic variation of corrosion promoting gases (sulfur dioxide and nitrogen dioxide), higher humidity, salt spraying and drying seem to be an aging test that reflects the different environments where the solar thermal collectors are exposed. In addition to the contaminants, drying / wetting cycles also play an important role in degradation mechanisms of absorber coatings.
- The behavior of thermally modified wood after exposure in maritime/industrial and urban environmentsPublication . Godinho, Delfina; Ferreira, Cristina; Lourenço, Ana; Araújo, Solange; Quilhó, Teresa; Cunha Diamantino, Teresa; Gominho, JorgeABSTRACT: Natural and thermally modified Pine, Ash, and Acacia woods were exposed in two different environments: urban and maritime/industrial. The weathering effects were evaluated during 24 months regarding color, chemical, and structural changes. In all wood species, thermal modification induced color, chemical, and structural changes. All woods became darker (Pine Delta L*: -32.01; Ash Delta L*: -36.83; Acacia Delta L*: -27.50), total extractives content increased (Pine: 19 %; Ash: 32 % and Acacia: 18 %), and the samples presented deformation and damaged cells. Total lignin was not significantly changed, although there were detected changes in lignin, namely the reduction of G -units in Pine (approximate to 2 %) and reduction of S/G ratio in Acacia (approximate to 0.04 %). Ash remained almost the same. After weathering, modified woods suffered fewer color changes, indicating that the thermal modification could improve the resistance to color change. Acacia wood, when exposed to maritime/industrial conditions, revealed a higher color change (Delta E: 35.7 at 24 months) when compared with urban conditions (Delta E: 23.5 at 24 months). Delignification, possibly caused by photodegradation, occurred in all wood samples, and the loss of extractive happened, perhaps caused by rain. Modified woods were slightly less resistant to weathering in maritime/ industrial environments. Some structural damage, namely cracked cells, the appearance of molds, blue staining, and particle deposition, was observed. The thermal modification enables color stabilization but does not seem to improve the weathering resistance in all studied wood species. Exposure to the different environments did not lead to significant differences in the morphology and chemical composition of the three natural and modified wood species.
- Avaliação de alternativas aos revestimentos com alcatrão de hulha para estruturas de aço total ou parcialmente imersas em estuário e água do marPublication . Alexandre, J. H.; Figueiredo, J. P.; Ferreira, Cristina; Vieira, Ana M. S.; Alves, Isabel Nascimento; Dias, Susana; Cunha Diamantino, TeresaNa procura de revestimentos anticorrosivos para protecção de estruturas de aço total ou parcialmente imersas em estuário e água do mar, que sejam alternativas mais ecológicas aos revestimentos com alcatrão de hulha ainda utilizados, foi desenvolvido um projecto no qual se comparam revestimentos epoxídicos comerciais com um revestimento de alcatrão de hulha epoxídico de referência, também comercial. Este trabalho inclui, para além da avaliação da protecção anticorrosiva dos revestimentos envolvidos no projecto, quer em laboratório, quer em exposição natural em estuário (rios Sado e Tejo) e em mar (Sines) durante quatro anos, a caracterização laboratorial das tintas integradas nos diferentes esquemas de pintura que deram origem aos revestimentos em estudo. Os resultados da avaliação no fim de dois anos de exposição natural, complementados com os ensaios em laborató permitiram concluir que dois dos quatro revestimentos alternativos estudados apresentaram melhor comportamento anticorrosivo do que o revestimento com alcatrão de hulha epoxídico usado como referência.
- Detection of corrosion on silvered glass reflectors via image processingPublication . Wiesinger, Florian; Baghouil, Sarah; Le Baron, Estelle; Collignon, Romain; Santos, Filipa; Cunha Diamantino, Teresa; Catarino, Isabel; Facão, Jorge; Ferreira, Cristina; Páscoa, Soraia; Sutter, Florian; Fernández-García, Aránzazu; Wette, JohannesABSTRACT: A novel characterization technique based on image analysis is presented, intended to complement state-of-the-art reflectometer measurements. The technique is developed by experts from different laboratories (OPAC, AGC, CEA and LNEG), which subsequently conduct two Round Robin experiments on corroded solar reflectors for validation. Regarding the inter-comparability, it is found that parameters like the corrosion spot density or the penetration maximum on coated edges exhibit an average coefficient of variation of 62.6 % and 54.9 %. Better agreement is found for parameters like the total corroded area and the maximum edge corrosion penetration, with coefficients of variation of 14.3 % and 13.4 %, respectively. The developed methodology is further applied during a 68-month lasting outdoor exposure campaign of two types of solar reflectors at two representative sites, one exhibiting corrosivity class C2 and the other C3. On the commercial coating RL1, a total corroded area of 59 mm2 and 426 mm2 is measured after the outdoor exposure on the C2 and the C3 site, respectively, while on the novel low-lead coated reflector RL3 corresponding values are 280 mm2 and 1308 mm2. This shows the superior quality of the coating RL1 in terms of corrosion resistance. Furthermore, the analysis highlights the importance of proper edge sealing for corrosion protection, since corrosion penetration is increased by a factor between 1.3 and 4.0 if the edges are unprotected. The reflectance decrease after the outdoor exposure is regarded as negligible (0.000 - 0.005), thus not permitting any of the conclusions that are made from the novel image analysis technique.
- Thermally modified wood: assessing the impact of weathering on mechanical strength and exposure to subterranean termitesPublication . Godinho, Delfina; Lourenco, Ana; Araújo, Solange; Machado, José Saporiti; Nunes, Lina; Duarte, Marta; Duarte, Sónia; Ferreira, Cristina; Quilhó, Teresa; Cunha Diamantino, Teresa; Gominho, JorgeABSTRACT: The main objective of this study was to evaluate the mechanical properties of three thermal-modified wood species when exposed to weathering in urban and maritime/industrial environments and their durability against subterranean termites. The wood species studied were Maritime pine, ash, and blackwood acacia. All wood samples were exposed to two different environments (urban and maritime/industrial) for 24 months. Then, its physical and mechanical properties were evaluated (modulus of elasticity (MOE), modulus of rupture (MOR), compression strength (CS), and modulus of compression (MOC). Thermally modified woods revealed a lower density, which could explain the loss of MOE and MOR. In compression, no significant changes were verified. The weathered samples showed changes in mechanical properties, mostly verified in MOE and MOR, where some decreases were reported in both locations. Tests were performed to evaluate biodegradation and the resistance of all wood samples to subterranean termites. The grade of attack (approximate to 4) and termite survival rate were similar in all wood species (above 75% and lower than 80%), except for modified acacia (59%), which could indicate that thermal modification increased toxic substances. The cellulose degradation was reflected in FTIR-ATR and Py-GC/MS in natural and thermally modified woods. Py-GC/MS showed a decrease in levoglucosan, while lignin suffered some modifications with slight changes in monomeric composition reflected by the reduction of the S/G ratio. No changes were found between the two environments, and thermal modification did not give extra protection against termites and weathering.