Browsing by Keyword "Electronic, Optical and Magnetic Materials"
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Item Antireflective mesoporous silica coatings by optimization of water content in acid-catalyzed sol-gel method for application in glass covers of concentrated photovoltaic modules(2019-01-15) Agustín-Sáenz, Cecilia; Machado, Maider; Tercjak, Agnieszka; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOSPorous silica layers with outstanding antireflective properties have been prepared by acid-catalyzed sol-gel process in presence of organic phases as structure directing agents (SDA) and excess water, with the aim of offering a cost-competitive, easy up-scaling and high efficiency process that contributes to reduce current levelized cost of energy (LCOE) of concentrating photovoltaics (CPV). The process has been optimized by controlling the water/alkoxide ratio, which is an important structure-regulating tool, having a strong influence in the structural properties of sol-gel synthesized materials. Hydrolysis of the inorganic precursor has been accomplished in high water/alkoxide conditions and in the presence of SDAs. Evaporation induced self-assembly (EISA) during coating deposition and the scanning of four types of SDAs have permitted to select the coating that fulfilled specific thickness and refractive index values with, in parallel, excellent results on sol stability. The final optimization has produced mesoporous coatings with ∼9 nm mean pore size, leading to an enhancement in transmittance up to 7.4% over bare glass in the 300–1500 nm wavelength range. The transmittance spectra have been used as inputs for the theoretical calculation of the short-circuit current density of a commercially available multijunction solar cell for CPV applications.Item Automatic pigmented lesion segmentation through a dermoscopy-guided OCT approach for early diagnosis(2019) López Sarachaga, Cristina; Lage, Sergio; Morales, Maria Celia; Boyano, Mª Dolores; Asumendi, Aintzane; Garrote, Estibaliz; Conde, Olga M.; Boyano, Ma Dolores; VISUAL; QuantumEarly diagnosis of pigmented lesions, specially melanoma, is an unmet clinical need that would help to improve patient prognosis. Apart from histopathological biopsy, the only gold standard non-invasive imaging technique during diagnosis is dermatoscopy (DD). Over the last years, new medical imaging techniques are being developed and Optical Coherence Tomography (OCT) has demonstrated to be very helpful on dermatology. OCT is non-invasive and provides in-depth structural microscopic information of the skin in real-time. In comparison with other novel techniques, as Reflectance Confocal Microscopy (RCM), the acquisition time is lower and the field-of-view higher. Hence, consolidated diagnosis techniques and novel imaging modalities can be combined to improve decision making during diagnosis and treatment. With actual methods, the delineation of lesion margins directly on OCT images during early stages of the disease is still really challenging and, at the same time, relevant from a prognosis perspective. This work proposes combining DD and OCT images to take advantage of their complementary information. The goal is to guide lesions delineation on OCT images considering the clinical features on DD images. The developed method applies image processing techniques to DD image to automatically segment the lesion; later, and after a calibration procedure, DD and OCT images become coregistered. In a final step the DD segmentation is transferred into the OCT image. Applying advanced image processing techniques and the proposed strategy of lesion delimitation, histopathological characteristics of the segmented lesion can be studied on OCT images afterwards. This proposal can lead to early, real-time and non-invasive diagnosis of pigmented lesions.Item Broadband antireflective coating stack based on mesoporous silica by acid-catalyzed sol-gel method for concentrated photovoltaic application(2018-11) Agustín-Sáenz, Cecilia; Sánchez-García, José Ángel; Machado, Maider; Brizuela, Marta; Zubillaga, Oihana; Tercjak, Agnieszka; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; INGENIERÍA DE SUPERFICIES; SISTEMAS FOTOVOLTAICOSSilica multi-layer stacks have been designed with the aim to provide broadband antireflective (AR) properties for glass components in concentrated photovoltaic (CPV) application. Silica porous coatings were grown by combining acid-catalyzed sol-gel route and evaporation induced self-assembly (EISA) method with four types of organic/inorganic systems. Sols were prepared using tetraethylorthosilicate (TEOS) as inorganic precursor assembled with two di-block copolymers, one tri-block copolymer and one cationic surfactant as organic templates. Optical properties were characterized by ellipsometry and spectrophotometry while the material structure was analyzed by environmental ellipsometric porosimetry (EEP) and atomic force microscopy (AFM). The concentration of inorganic and organic phases was optimized and a broadband AR bi-layer stack was obtained providing a 7.2% (under the reference AM1.5 solar spectral irradiance) increase in transmittance over bare glass in the wavelength range 300–2000 nm when coated on both sides.Item Changes of solar cell parameters during damp-heat exposure(2016-10-01) Zhu, Jiang; Koehl, Michael; Hoffmann, Stephan; Berger, Karl Anton; Zamini, Shokufeh; Bennett, Ian; Gerritsen, Eric; Malbranche, Philippe; Pugliatti, Paola; Di Stefano, Agnese; Aleo, Francesco; Bertani, Dario; Paletta, Fabrizio; Roca, Francesco; Graditi, Giorgio; Pellegrino, Michele; Zubillaga, Oihana; Cano, F.J.; Pozza, Alberto; Sample, Tony; Gottschalg, Ralph; Iranzo, F. J.Cano; SISTEMAS FOTOVOLTAICOS; SGThe electrical ageing of photovoltaic modules during extended damp-heat tests at different stress levels is investigated for three types of crystalline silicon photovoltaic modules with different backsheets, encapsulants and cell types. Deploying different stress levels allows determination of an equivalent stress dose function, which is a first step towards a lifetime prediction of devices. The derived humidity dose is used to characterise the degradation of power as well as that of the solar cell's equivalent circuit parameters calculated from measured current–voltage characteristics. An application of this to the samples demonstrates different modes in the degradation and thus enables better understanding of the module's underlying ageing mechanisms. The analysis of changes in the solar cell equivalent circuit parameters identified the primary contributors to the power degradation and distinguished the potential ageing mechanism for each types of module investigated in this paper. © 2016 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd. © 2016 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd.Item Characterization of nanostructured Ti–B–(N) coatings produced by direct current magnetron sputtering(2007-02-26) López-Cartes, C.; Martínez-Martínez, D.; Sánchez-López, J.C.; Fernández, A.; García-Luis, A.; Brizuela, Marta; Onate, J.I.; TECNOLOGÍAS DE HIDRÓGENO; INGENIERÍA DE SUPERFICIES; Tecnalia Research & InnovationA series of Ti–B–(N) coatings prepared by dc magnetron sputtering using TiB2 targets in Ar/N2 gas mixtures has been chemically and structurally characterized by transmission electron microscopy, X-ray diffraction, electron energy-loss spectroscopy, and X-ray photoelectron spectroscopy. The influence of synthesis parameters such as applied heating power and nitrogen flow on the structure and chemical composition of the coatings has been studied. Independently of the experimental conditions employed during the synthesis, hexagonal TiB2 is the main crystalline phase present in the coatings. The use of N2 leads to the formation of an amorphous mixture of BN/TiN phases, as well as a diminution of the TiB2 crystalline phase. The influence of the composition and structure of the coatings on their hardness is also discussed.Item Compact and cost effective instrument for detecting drug precursors in different environments based on fluorescence polarization(SPIE-INT SOC OPTICAL ENGINEERING, 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA, 2013) Antolín-Urbaneja, Juan Carlos; Eguizabal, I.; Briz, N.; Dominguez, A.; Estensoro, Patxi; Secchi, A.; Varriale, A.; Di Giovanni, S.; D´Auria, S.; Tecnalia Research & Innovation; ROBOTICA_AUTOMA; TECNOLOGÍAS DE HIDRÓGENO; SG; MAQUINAS; GENERALSeveral techniques for detecting chemical drug precursors have been developed in the last decade. Most of them are able to identify molecules at very low concentration under lab conditions. Other commercial devices are able to detect a fixed number and type of target substances based on a single detection technique providing an absence of flexibility with respect to target compounds. The construction of compact and easy to use detection systems providing screening for a large number of compounds being able to discriminate them with low false alarm rate and high probability of detection is still an open concern. Under CUSTOM project, funded by the European Commission within the FP7, a stand-alone portable sensing device based on multiple techniques is being developed. One of these techniques is based on the LED induced fluorescence polarization to detect Ephedrine and Benzyl Methyl Keton (BMK) as a first approach. This technique is highly selective with respect to the target compounds due to the generation of properly engineered fluorescent proteins which are able to bind the target analytes, as it happens in an “immune-type reaction”. This paper deals with the advances in the design, construction and validation of the LED induced fluorescence sensor to detect BMK analytes. This sensor includes an analysis module based on high performance LED and PMT detector, a fluidic system to dose suitable quantities of reagents and some printed circuit boards, all of them fixed in a small structure (167mm x 193mm x 228mm) with the capability of working as a stand-alone application.Item Composite material incorporating protective coatings for photovoltaic cell encapsulation(2022-09-15) Yurrita, Naiara; Aizpurua, Jon; Cambarau, Werther; Imbuluzqueta, Gorka; Hernández, Juan M.; Cano, Francisco J.; Huerta, Irene; Rico, Elena; Caño, Teodosio del; Wölper, Sarah; Haacke, Florian; Zubillaga, Oihana; Tecnalia Research & Innovation; SISTEMAS FOTOVOLTAICOS; SGPhotovoltaic modules consisting of one back-contact cell were manufactured by vacuum resin infusion process using glass reinforced epoxy composite as encapsulant where the cells are embedded. Incorporation of three coatings onto the composite surface was studied with the aim to improve the electrical performance stability of the modules under ultraviolet (UV), thermal cycling and damp-heat environmental weathering. Photovoltaic and aging performance were examined through the short-circuit current density values and colour change of the composite. Decrease in the initial photovoltaic performance of the modules was caused by the coating deposition. The highest drop in the initial values was observed for the varnish type coating, showing a decrease of 2.6% in short-circuit current. Regarding the performance stability, the decrease was more pronounced in the damp-heat test, presenting the varnish type coating the minimum loss of 1.4% in short-circuit current and a variation of 87% in b* chromatic parameter after 1000 h exposure at 85 °C and 85% relative humidity. The study concluded that the protective coating should be selected to provide the composite modules with an optimal trade-off between the initial electrical performance and the desired stability, with further research work targeted to improve moisture barrier properties.Item Composite material with enhanced ultraviolet performance stability for photovoltaic modules(2019-09-15) Imbuluzqueta, Gorka; Yurrita, Naiara; Aizpurua, Jon; Cano, Francisco J.; Zubillaga, Oihana; SISTEMAS FOTOVOLTAICOS; SGThe present work aims encapsulating photovoltaic cells in glass reinforced epoxy composite by vacuum resin infusion, incorporating additives directed to enhance the performance stability of the manufactured photovoltaic modules under ultraviolet (UV) exposure. UV absorber (UVA) and hindered amine light stabilizer (HALS) additives were incorporated in the resin system in different content. Photovoltaic performance and stability under UV radiation exposure were studied through external quantum efficiency (EQE) spectra, chromatic coordinates and short-circuit current values. Decrease in current values and increase in yellowness were observed in the presence of UVA and HALS. However, an enhanced performance stability was observed when additives are incorporated, improving the stability when increasing the additive amount. The most stable module, with cells embedded in 2% additive containing composite, showed a 2.7% short-circuit current loss after UV aging exposure.Item Corrosion testing device for in-situ corrosion characterization in operational molten salts storage tanks: A516 Gr70 carbon steel performance under molten salts exposure: A516 Gr70 carbon steel performance under molten salts exposure(2016-12-01) Ruiz-Cabañas, F. Javier; Prieto, Cristina; Osuna, Rafael; Madina, Virginia; Fernández, A. Inés; Cabeza, Luisa F.; MATERIALES PARA CONDICIONES EXTREMASConcentrated solar power (CSP) generation is becoming a very important player within the renewable energy sector thanks to increased introduction of these facilities into the conventional electricity market. CSP plants become dispatchable when integrating thermal energy storage (TES) systems which allow electricity production at any time of the year. Sensible TES using nitrate salts mixtures as storage fluid are the most extended arrangement for commercial CSP facilities. In addition to storage time, dimensions, thermal-mechanical requirements, among others, corrosion compatibility between high temperature nitrate salts, and structural materials is a key factor to take into consideration for the final storage system design. Many scientific contributions have been developed regarding metallic alloys corrosion performance in nitrate salts at laboratory scale. Accordingly, lack of technical background is identified about nitrates corrosion in relevant operation conditions. Therefore, a corrosion testing device (CTD) was designed to evaluate corrosion behavior of structural materials inside high temperature nitrate salts storage tanks in operation. Furthermore, A516 Gr70 carbon steel was evaluated at different exposures times by using the CTD in the TES-PS10 pilot plant. Results reported within this study show the feasibility of the CTD to be used at commercial scale allowing corrosion preventive maintenance practices and materials selection optimization. Moreover, A516 Gr70 carbon steel displayed an excellent corrosion performance after nitrate salts exposure being recommended for long time service under continuous and intermittent exposure to nitrate salts. In addition to low corrosion rates, carbon steel generated protective and well adhered iron oxide layers without significant localized phenomena. Finally, negligible susceptibility to crevice and stress corrosion cracking (SCC) phenomena is showed by carbon steel under test conditions.Item Design and Testing of Real-Scale MgB2 Coils for SUPRAPOWER 10-MW Wind Generators(2016-04) Sarmiento, G.; Sanz, Santiago; Pujana, A; Merino, Jose Maria; Marino, Iker; Tropeano, Matteo; Nardelli, Davide; Grasso, Gianni; Tecnalia Research & Innovation; DIGITAL ENERGYSuperconducting MgB2 coils have a promising application niche in large wind generators. The potential implementation as field coils results in machines with smaller size and reduced weight, which is a real benefit compared to conventional nonsuperconducting alternatives. This is a key factor where the wind market demands higher power rate and more compact turbines in order to optimize capital and operational costs. Under the SUPRAPOWER project, a 10-MW direct-drive wind generator concept will be probed through an experimental validator, with superconducting rotating dc coils. For the required temperature, current density, and magnetic field, the available commercial MgB2 wire has been selected, as it is cost effective and well suited compared to other solutions. The aim of the present work is to analyze the operational conditions of MgB2 dc field coils, which are cryogen-free cooled and developed in accordance with SUPRAPOWER generator requirements. This paper deals with the design, manufacturing, and experimental results of full-scale superconducting coils.Item Development of a resistivity standard for polymeric materials used in photovoltaic modules(SPIE, 2015) Kempe, Michael D.; Miller, David C.; Nobles, Dylan L.; Sakurai, Keiichiro; Tucker, John; Bokria, Jayesh G.; Shioda, Tsuyoshi; Nanjundiah, Kumar; Yoshihara, Toshio; Birchmier, Jeff; Zubillaga, Oihana; Wohlgemuth, John H.; Dhere, Neelkanth G.; Jones-Albertus, Rebecca; Wohlgemuth, John H.; SISTEMAS FOTOVOLTAICOSPhotovoltaic (PV) modules, operate at high voltages and elevated temperatures, and are known to degrade because of leakage current to ground. Related degradation processes may include: electric/ionic corrosion, electrochemical deposition, electromigration, and/or charge build-up in thin layers. The use of polymeric materials with a high resistivity is known to reduce the rate of potential induced degradation processes. Because of this, PV materials suppliers are placing increased importance on the encapsulant bulk resistivity, but there is no universally accepted method for making this measurement. The development of a resistivity test standard is described in this paper. We have performed a number of exploratory and round-robin tests to establish a representative and reproducible method for determining the bulk resistivity of polymeric materials, including encapsulation, backsheet, edge seals, and adhesives. The duration of measurement has been shown to greatly affect the results, e.g., an increase as great as 100X was seen for different measurement times. The standard has been developed using measurements alternating between an on and off voltage state with a weighted averaging function and cycle times of an hour.Item Effect of addition of silica- and amine functionalized silica-nanoparticles on the microstructure of calcium silicate hydrate (C-S-H) gel(2015-07-05) Monasterio, Manuel; Gaitero, Juan J.; Erkizia, Edurne; Guerrero Bustos, Ana M.; Miccio, Luis A.; Dolado, Jorge S.; Cerveny, Silvina; Tecnalia Research & Innovation; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNIn this work we study the influence of adding nano-silica (SiO2, Nyasil™) and aminopropyl (-(CH2)3-NH2,) functionalized silica nanoparticles (Stoga) during the synthesis of calcium-silicate-hydrate (C-S-H gel). Characterization by solid state 29Si NMR and ATR-FTIR spectroscopy showed that the addition of both particle types increases the average length of the silicate chains in C-S-H gel being this effect slightly more important in the case of Stoga particles. In addition, 13C NMR and XPS confirmed that the aminopropyl chain remains in the final product cleaved to silicon atoms at the end of the silicate chain of C-S-H gel whereas XRD measurements showed that this result in an increment in the basal distance compared with ordinary CSH. In addition, the dynamics of water within the pores of C-S-H gel was analyzed by broadband dielectric spectroscopy. We observed that water confined in C-S-H formed with the addition of nanoparticles is faster than that in plain C-S-H which can be related to a different porous structure in these materials.Item Effect of aryl phosphates on toxicity of combustion gases of flame‐retardant polycarbonate/acrylonitrile butadiene styrene blends according to EN 45545 railway standard(2022-03-09) Sánchez, Alberto; Villanueva, Sara; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNIn this study, the toxicity of combustion gases of polycarbonate/acrylonitrile butadiene styrene (ABS) blends that include aryl phosphates as flame-retardants (FRs) was analyzed according to the European railway standard EN 45545-2 (NBS chamber + FTIR). FRs have a significant influence on the evolution of the toxicity of gases generated during the combustion process. In the experiment, the asphyxiant hydrogen cyanide (HCN) was detected at the beginning of combustion (4 min of testing) as a product of ABS degradation. CO was generated throughout the test (8 min) because of the incomplete combustion of both the ABS and PC fractions. The presence of aryl phosphates promoted the inhibition of the flame. The reaction of PO radicals in the gas phase resulted in OH scavenging and a higher release of HCN and CO. The results suggest that aryl phosphates act in the first 4 min and do not have an effect later. FRs with lower thermal stability exhibited lower heat release and flame propagation but generated more toxic gases. This effect is attributed to the higher activity of the flame-retardant in the gas phase. Further, additional fire performance parameters, including thermal stability (thermogravimetric analysis), flammability (UL94), and heat and smoke generation (cone calorimeter), were studied. It was found that aryl phosphates reduced the fire hazard, prevented the spread of the flame, reduced heat generation, increased the time to ignition, and, at the same time, promoted the emission of toxic gases that differ in function of the selected flame-retardantItem Effect of organic precursor in hybrid sol–gel coatings for corrosion protection and the application on hot dip galvanised steel(2019-01-15) Agustín-Sáenz, Cecilia; Martín-Ugarte, Eider; Jorcin, Jean Baptiste; Imbuluzqueta, Gorka; Santa Coloma, Patricia; Izagirre-Etxeberria, Usoa; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; MATERIALES PARA CONDICIONES EXTREMAS; SISTEMAS FOTOVOLTAICOS; INGENIERÍA DE SUPERFICIESSol-gel coating material with enhanced corrosion protection for zinc-coated steel has been obtained through the incorporation of mono-phenol and bi-phenol organic precursors in an epoxide functionalised-silica-zirconia matrix. The effect of the presence of the organic precursors in the baseline formulation has been studied; sol stability has been examined by viscosity evolution; gel densification stage has been studied by differential scanning calorimetry (DSC); material composition has been analysed by Fourier transform infrared spectroscopy (FTIR) and X-ray spectroscopy (XPS); coating thickness and roughness has been measured by profilometry. Corrosion performance in three artificial weathering tests showed outstanding performance in the delay of zinc and steel corrosion products emergence, and electrochemical impedance spectroscopy (EIS) measurement permitted the identification of the coating presenting the most promising properties in terms of corrosion protection. Developed coatings have shown outstanding contribution to service life extension of zinc-coated parts.Item Enhanced photostability and sensing performance of graphene quantum dots encapsulated in electrospun polyacrylonitrile nanofibrous filtering membranes(2018-06-01) Ruiz, Virginia; Pérez-Marquez, Ana; Maudes, Jon; Grande, Hans-Jürgen; Murillo, Nieves; Tecnalia Research & Innovation; PRINTEXWe report a method to encapsulate graphene quantum dots (GQD) in polyacrylonitrile (PAN) nanofibrous membranes to manufacture robust filtering membranes by electrospinning. GQD-PAN membranes with different nanofiber diameter were prepared tuning the electrospinning parameters, all exhibiting the characteristic fluorescence fingerprint of the GQD probes. The photoluminescence (PL) stability of GQD embedded in the PAN fibers was significantly enhanced with respect to that of water dispersed GQD luminescent probes. The PL of GQD-PAN filtering membranes showed remarkable time stability, both stored dry and immersed in phosphate buffer solutions (PBS), as well as exposed to continuous light irradiation. However, the PL intensity of GQD-PAN membranes was irreversibly quenched by highly oxidant free chlorine solutions. Thus, electrospun GQD-PAN membranes exhibited excellent performance as turn-off fluorescence sensing platforms for free chlorine detection in PBS 0.1 M pH 7. The analytical performance of GQD-PAN membranes was comparable to that of GQD solutions with optimal concentrations, displaying a fast (no need of incubation time) and linear response to chlorine concentration in the 10–600 μM range, a low detection limit of 2 μM, high sensitivity, reproducibility and selectivity. Moreover, the sensing performance of the membranes was very stable after being immersed in PBS for months, outperforming the stability of GQD solutions.Item Experimental Study and Simulation of Quench in MgB2 Coils for Wind Generators(2016-01-18) Sanz, Santiago; Sarmiento, G.; Pujana, Ainhoa; Merino, Jose Maria; Tropeano, Matteo; Nardelli, Davide; Grasso, Gianni; Sun, Jiuce; Toral, Fernando; Marino, Iker; Tecnalia Research & Innovation; DIGITAL ENERGYIn the frame of the European Union (EU) founded SUPRAPOWER Project, MgB2 conduction-cooled coils are foreseen to be used in the rotor of synchronous wind turbine generators. As a result, a conceptual design of a 10 MW superconducting (SC) generator will be made and a Rotating Magnetic Validator (RMV) will be constructed and tested, with two rotating SC coils. The main dimensions and working conditions will be kept in the RMV and in the 10 MW generator. The RMV has been conceived is such a way that it can be transformed in a generator. Numerical quench simulations have to be performed in order to design a suitable quench protection system. Due to the uncertainty of some material properties and its importance for the machine operation, an experimental validation must be performed in order to resolve discrepancies. Under this premises, a full size MgB2 double pancake coil have been manufactured and instrumented to trigger a controlled quench.Item High selectivity ZIF-93 hollow fiber membranes for gas separation(2015-07-18) Cacho-Bailo, Fernando; Caro, Guillermo; Etxeberría-Benavides, Miren; Karvan, Oʇuz; Téllez, Carlos; Coronas, Joaquín; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Tecnalia Research & InnovationZeolitic imidazolate framework-93 (ZIF-93) continuous membranes were synthesized on the inner side of P84 co-polyimide hollow fiber supports by microfluidics. MOFs and polymers showed high compatibility and the membrane exhibited H2-CH4 and CO2-CH4 separation selectivities of 97 (100 °C) and 17 (35 °C), respectively.Item Hydrophobic and spectrally broadband antireflective methyl-silylated silica coatings with high performance stability for concentrated solar applications(2019-09-15) Agustín-Sáenz, Cecilia; Machado, Maider; Zubillaga, Oihana; Tercjak, Agnieszka; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; SISTEMAS FOTOVOLTAICOSAn efficient and environment-friendly process, consisting of acid-catalyzed sol-gel process combined with evaporation induced self-assembly, was conducted to build antireflective (AR) layer stacks for concentrated solar applications. Considering the external factors that may alter the optical properties of the system when operating outdoors, such as soiling, harsh climate conditions and alkali ions diffusion from glass, several stack configurations were proposed. Particularly, the effect of a methyl-silylating post-treatment, the presence of the inner layer and the optimization of sintering temperature have been devised in order to minimize soiling adherence and alkali diffusion from the glass substrate and to assure the required robustness to comply with the durability requirements. The assessment consisted of (i) an analysis of the optical transmittance, reflectance and refractive index and (ii) hydrophobicity and effect of water absorption on the external porous coatings in relation to the results of accelerated aging tests following photovoltaics standards. The main goal was to achieve the most rational design, based on a proper trade-off between cost efficiency, processability, optical properties and reliability during real life operation.Item Laser hybrid joining of plastic and metal components for lightweight components(SPIE-INT SOC OPTICAL ENGINEERING, 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA, 2015) Rauschenberger, J.; Cenigaonaindia, A.; Keseberg, J.; Vogler, D.; Gubler, U.; Liébana, F.; Dorsch, Friedhelm; COMPOSITEPlastic-metal hybrids are replacing all-metal structures in the automotive, aerospace and other industries at an accelerated rate. The trend towards lightweight construction increasingly demands the usage of polymer components in drive trains, car bodies, gaskets and other applications. However, laser joining of polymers to metals presents significantly greater challenges compared with standard welding processes. We present recent advances in laser hybrid joining processes. Firstly, several metal pre-structuring methods, including selective laser melting (SLM) are characterized and their ability to provide undercut structures in the metal assessed. Secondly, process parameter ranges for hybrid joining of a number of metals (steel, stainless steel, etc) and polymers (MABS, PA6.6-GF35, PC, PP) are given. Both transmission and direct laser joining processes are presented. Optical heads and clamping devices specifically tailored to the hybrid joining process are introduced. Extensive lap-shear test results are shown that demonstrate that joint strengths exceeding the base material strength (cohesive failure) can be reached with metal-polymer joining. Weathering test series prove that such joints are able to withstand environmental influences typical in targeted fields of application. The obtained results pave the way toward implementing metal-polymer joints in manufacturing processes.Item Materials selection for thermal energy storage systems in parabolic trough collector solar facilities using high chloride content nitrate salts(2017-04-01) Ruiz-Cabañas, F. Javier; Prieto, Cristina; Madina, Virginia; Fernández, A. Inés; Cabeza, Luisa F.; MATERIALES PARA CONDICIONES EXTREMASThe increasing role of concentrated solar power (CSP) within the renewable energy portfolio is attributed to the possibility of integrating thermal energy storage (TES) systems. Then, CSP technology has become one of the most interesting clean options to deliver dispatchable power on demand. Nowadays, commercial facilities use high quality solar salts (60%:40% NaNO3 and KNO3 by weight) as storage medium due to the attractive properties of this fluid to be applied under CSP operation conditions. Taking into account that CSP installations are designed with really large TES systems containing tens of thousands of tons, the use of lower quality nitrates salts would reduce the molten salts inventory cost and finally the investment cost of the CSP storage systems at commercial scale. The most important drawback of selecting low quality nitrates salts for high temperature CSP applications is the corrosion impact produced by impurities. Accordingly, chlorides have been identified in the state of the art as the impurity with higher effect over corrosion. This work is focused on A516 Gr70 carbon steel corrosion performance evaluation under high-chlorides content nitrates salts (1.2% and 3% by weight) at 400 °C. In addition, the feasibility of using the proposed low purity mixtures with current CSP facilities materials selection is analyzed. Results reported within this study show the critical effect of chloride content over corrosion mechanism producing lack of adherence between base metal and oxides layers in addition to corrosion products delamination and internal cracking. Then, the use of A516 Gr70 carbon steel is rejected for a long term design under solar salts containing chlorides content in the range 1.2–3% by weight being necessary a higher corrosion resistant materials selection. An improved materials selection focused on higher corrosion resistance alloys is discussed.