A carregar...
Projeto de investigação
Sem título
Financiador
Autores
Publicações
Laser-induced copper superhydrophobicity to improve heat transfer and reduce limestone deposition in water heating systems
Publication . Gaspar, Guilherme; Salvador, Maria A.; Pereira, Maria J.; Carvalho, Alexandre F.; Amaral, Vitor S.; Tedim, João; Deuermeier, Jonas; Fernandes, António J. S.; Silva, Rui F.; Costa, Florinda M.; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; North-Holland | Elsevier
The spectroscopic and electrochemical properties of copper (Cu) superhydrophobic surfaces produced from laser scribing operating in the nanosecond pulsing regime are reported herein. µ-Raman spectroscopy highlighted the synthesis of copper oxide films with the simultaneous sharp increase of the substrates’ specific surface area through one single laser processing step. Higher laser power densities resulted in cupric oxide (CuO) with higher crystallinity and more homogeneous surface chemistry, whereas cuprous oxide (Cu2O) dominates surfaces processed at lower laser power densities. Steady-state contact angles using water of 162° ± 9° were measured for the lowest laser power employed, representing a grounded and meaningful development for substrates of this kind using laser technology. The results show that the combination of surface roughness and the presence of Cu2O and hydrocarbon chains at the surface contributed to the superhydrophobicity of the copper foils. Additionally, variations in the thermal conductivity of the samples’ surface are influenced by changes in the chemical composition. The surfaces were exposed to limestone-rich water and the amount of deposited solute was quantified using atomic absorption spectrometry. A fivefold reduction in calcium carbonate (CaCO3) was observed, unequivocally demonstrating the impact of laser treatments in reducing CaCO3 nucleation rates in Cu for water heating applications.
The bimodal Fii-A2-type and calc-alkaline volcanic sequence of the Aljustrel brownfield region, Iberian Pyrite Belt, SW Iberian Massif
Publication . Amaral, João Lains; Solá, Ana Rita; Bento dos Santos, Telmo M.; Feitoza, Lorena; Tassinari, Colombo; Crispim, Lourenço; Chichorro, Martim; Zieger-Hofmann, Mandy; Gärtner, Jessica; Linnemann, Ulf; Gonçalves, João; GeoBioTec - Geobiociências, Geoengenharias e Geotecnologias; Elsevier GmbH
The Iberian Pyrite Belt (IPB) is a late Devonian – Early Carboniferous world-class polymetallic VMS province that includes significant Cu-(Sn)-Pb-Zn-(Ag) deposits of massive sulphides and feeder zones. The Aljustrel brownfield region contains one of the highest concentrations of ore in the IPB in 6 known deposits (Gavião, São João, Moinho, Algares, Estação and Feitais). To delve into the petrogenesis of the Aljustrel early Carboniferous (∼355 Ma) felsic-dominated bimodal volcanism, new whole-rock trace elements and Sm[sbnd]Nd isotopes, and U[sbnd]Pb in zircon were obtained. Based on Ga/Al and Y/Nb ratios, it is shown that Aljustrel felsic magmatism has the geochemical features of A2-type melts, typical of post-collisional and back-arc settings. U[sbnd]Pb in zircon for a juvenile felsic volcanic rock point to antecrysts ages spanning from 387.9 to 366.6 Ma and a maximum emplacement age of 354.3 ± 2.6 Ma. These long-lasting melting events, present in both juvenile (ƐNdi = +1.79) and evolved felsic rocks (ƐNdi = −5.07), imply heterogeneous sources dominated by zircon-bearing igneous rocks. The Sm[sbnd]Nd model ages are in accordance with previous Lu[sbnd]Hf model ages in zircon, reinforcing that the isotopic variability is related to the same petrogenetic process. Subordinated Aljustrel mafic rocks, coeval with the abundant felsic volcanism, show orogenic signatures, namely Nb-Ta-Ti negative anomalies and calc-alkaline affinities, whereas Sm[sbnd]Nd isotopic data (ƐNdi = +1.54 to +5.48) points to variable to no contamination with crustal material. These geochemical results suggest derivation from an enriched mantle source modified by subduction metasomatism. In addition, the mafic rocks did not provide zircons for geochronological analysis, with the exception of one sample, in which a Concordia age of 402.1 ± 15.5 Ma was obtained from a single grain. The combined geochemical signatures of mafic and felsic volcanic rocks suggest asthenospheric rise, but this solely does not explain the abundance of zircon antecrysts in the felsic rocks. Therefore, a geodynamic model that includes a continuous evolution from Devonian to Carboniferous times is inferred. This more complex and broader geodynamic model for the Iberian Pyrite Belt in which successive metal remobilization occurred after successive melting events, fits the present geochemical data and is more likely to explain why the Iberian Pyrite Belt is a unique metallogenetic province.
Unidades organizacionais
Descrição
Palavras-chave
Contribuidores
Financiadores
Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
Concurso de avaliação no âmbito do Programa Plurianual de Financiamento de Unidades de I&D (2017/2018) - Financiamento Base
Número da atribuição
UIDB/50019/2020