Functional properties of ceramic-Ag nanocomposite coatings produced by magnetron sputtering

In recent years, the use of nanocomposite materials to functionalize surfaces has been investigated, taking advantage of the complementary properties of the nanocomposite constituents. Among this family of materials, ceramic-Ag coatings have been widely studied due to the large variety of functionalities that silver possesses and the possibility of tuning the coating’s practical features by selecting the proper matrix to support this noble metal. Therefore, this review focuses on the effects of silver nanoparticles on the functional properties of ceramic-Ag nanocomposites. The chemistry, structure, morphology and topography of the coatings are analyzed with respect to the changes produced by the silver nanoparticles’ distribution, amount and sizes and by altering production process variables. To offer a clear understanding of the functionalities of these materials, the optical, electrical, mechanical, tribological, electrochemical and biological properties reported in the last decade are reviewed, focusing on the ability to tune such properties by modifying the silver distribution, morphology and composition. In particular, the surface plasmon resonance, self-lubricating ability and antibacterial effect of silver are covered in detail, establishing their correlation with factors such as silver diffusion, segregation and ionization.This research is partially sponsored by FEDER funds through the program COMPETE-Programa Operacional Factores de Competitividade and by Portuguese national funds through FCT-Fundação para a Ciência e a Tecnologia, under the projects ANTIMICROBCOAT - PTDC/CTM/102853/2008 and in the framework of the Strategic Projects PEST-C/FIS/UI607/2011, PEST-C/EME/UI0285/2011 and SFRH/BD/80947/2011. The authors would like to thank the ‘‘Surface Modification and Functionalization - Research Group (SMF)” for advice during the development of this review

Production and characterization of ZrCN-Ag coatings deposited by mganetron sputtering

Tese de Doutoramento (Programa doutoral em Engenharia de Materiais)Zr-C-N coatings, incorporating silver as antibacterial agent, are deposited onto stainless steel 316L (SS316L) and Si (100) substrates by unbalanced magnetron sputtering; their corrosion and tribological properties were evaluated to understand their potential to be used in joint orthopedic devices. Zirconium carbonitride was selected owing to both its excellent biocompatibility and non-toxic behavior. Despite ZrCN has been widely studied, no other report on the deposition and characterization of Zr-C-N-Ag coatings exist in the literature, to the author knowledge. Therefore, the contribution of this project for the state of the art on Zr-C-N system alloyed novel metallic elements is: (i) A structural characterization, including the phase composition, based on the identification of crystalline (X-ray diffraction and transmission electron microscopy) and amorphous phases (Raman spectroscopy), and the chemical composition of the material both in bulk (electron probe microanalysis) and at the surface (X-ray photonelectron spectroscopy). The morphology of the coatings was also studied (scanning electron microscopy), in order to evidence the influence of the deposition parameters on the coatings cross-section and surface morphology, and correlate them with the functional properties. (ii) In order to optimize the adhesion, mechanical and electrochemical properties of the coatings; an optimization method was applied to the deposition process to decrease the final number of coating runs. (iii) The in-depth electrochemical and tribological characterization of the coatings was performed in a Hank’s balanced salt solution with 10 gr/L of bovine serum albumin, in order to mimic as much as possible the condition of the biological fluid of human body. In Zr-C-N-Ag system a diversity of phases can occur, such as zirconium carbonitride (ZrCN), amorphous carbon (a-C or a-(C, N)) and metallic silver (Ag). By controlling the deposition conditions, it is possible to adjust the amount of each phase, and then, to tune the properties of the system. The optimization of the deposition process shows that the ideal composition of the Zr-C-N-Ag coatings is attained when the Zr2CN phase is deposited, with less than 8 at. % of silver nanoparticles, allowing achieving the best compromise between mechanical, electrochemical and tribological properties. The electrochemical evaluation reveals that both silver and amorphous carbon phases are detrimental to the corrosion resistance. The increase of silver triggers a more active electrochemical reactions in the system that increases the corrosion process. In addition, the combination of silver and amorphous phases produces a more electrochemical porous materials, which promotes the penetration of the electrolyte. Although marginally, silver also negatively affects the wear resistance of the system, when tested against an ultra-high molecular weight polyethylene, due to a delay it causes in the formation of a protective albumin layer. The coefficient of friction (COF) of the coatings, did not show any correlation with the amount of silver, while the amorphous carbon phases seems to reduce the COF. Finally, the phase distribution showed a relevant role in the silver ion release to the electrolyte, as a function of the silver nanoparticles surrounding. This distribution of phases creates nanogalvanic couples in the system that controls the silver ion release, depending on a:C or ZrCN phases, the oxidation of silver can be enhanced or retarded, respectively. The antibacterial effect of the system does not have a direct relation with the silver ion release. Even coatings with low silver ion release may possess antibacterial capabilities, if silver is highly agglomerated on the surface.Neste trabalho foram depositados revestimentos do sistema Zr-C-N-Ag, incorporando a prata como um agente antibactericida, em substratos de aço inoxidável 316L e silício (100), utlizando a técnica de pulverização catódica por magnetrão. Os revestimentos foram caraterizados no que concerne o seu comportamento tribológico e à corrosão, no sentido de compreender o seu potencial para serem utilizados em próteses ortopédicas. O zircónio foi selecionado por causa da sua biocompatibilidade e comportamento não tóxico. Ao conhecimento do autor, apesar do sistema ZrCN ter sido amplamente estudado, não existe na literatura qualquer referência à investigação deste sistema incorporando prata. Assim, a contribuição deste trabalho para o estado da arte dos revestimentos Zr-C-N com adições de outros elementos é: (i) Caraterização estrutural, incluindo a análise da composição fásica, baseada quer na identificação das fases cristalinas (difração de raios X e microscopia eletrónica de transmissão) e amorfas (espectroscopia Raman) quer na avaliação da composição química dos revestimentos, no maciço (microssonda eletrónica) e na superfície (espectroscopia de fotoeletrões de raios X). A morfologia dos revestimentos em superfície e secção transversal foi analisada por microscopia eletrónica de varrimento, pondo em evidência a influência dos parâmteros de deposição na rugosidade e compacidade dos revestimentos. (ii) De modo a otimizar a adesão e as propriedades mecânicas e eletroquímicas dos revestimentos, um método de otimização foi aplicado ao processo de deposição para diminuir o número total de experiências. (iii) A caraterização eletroquímica e tribológica dos revestimentos foi realizada numa solução salina balanceada com 10 gr/L de albumina sérica bovina de modo a mimetizar as condições dos fluidos biológicos caraterísticos do corpo humano. Podem occorrer no Sistema Zr-C-N-Ag diversas fases, tais como os carbonitretos de zircónio (ZrCN), carbono amorfo (a-C or a-(C, N)) e prata metálica (Ag). Controlando as condições de deposição, é possível ajustar a quantidade de cada uma das fases e, então, alcançar as propriedades desejadas. A otimização do processo de deposição mostra que a composição ideal para os revestimentos de Zr-C-N-Ag é atingida quando é depositada a fase Zr2CN, com menos de 8 % at. de nanopartículas de prata, permitindo encontrar o melhor compromisso entre propriedades mecânicas, eletroquímicas e tribológicas. A caraterização eletroquímica permitiu concluir que ambas as fases de prata e de carbono amorfo são prejudiciais para a resistência à corrosão. Adicionalmente, a prata tem uma ação negativa na resistência ao desgaste do sistema, quando os testes são realizados contra um contracorpo de polietileno de alta densidade de elevado peso molecular, devido ao atraso que ela provoca na formação no contato da camada protetora de albumina. Finalmente, a distribuição de fases tem um papel relevante na libertação de iões de prata para o eletrólito, dependente da vizinhança que têm as nanopartículas de prata. Dependendo de haver a fase de carbono amorfo ou de ZrCN, a oxidação da prata pode ser, respetivamente, realçada ou retardada. O efeito antibactericida do sistema não tem uma relação direta com a libertação dos iões de prata. Mesmo revestimentos com libertação de iões de Ag reduzida podem possuir capacidades antimicrobianas, se houver suficiente teor de prata aglomerada na superfície.This thesis was financially supported by a PhD scholarship from Fundação para a Ciência e Tecnologia (Ref.: SFRH/BD/80947/2011), inserted in the Programa Potencial Humano Quadro de Referência Estratégico Nacional (POPH - QREN) Tipologia 4.1 – Formação Avançada. The POPH-QREN is co-financed by Fundo Social Europeu (FSE) and by Ministério da Ciência, Tecnologia e Ensino Superior (MCTES)

Ag+ release and corrosion behavior of zirconium carbonitride coatings with silver nanoparticles for biomedical devices

Zirconium carbonitride coatings with silver nanoparticles were produced by DC unbalanced dual magnetron sputtering system, using two targets, Zr and Zr/Ag in an Ar, C2H2 and N2 atmosphere. Stainless steel 316L and silicon (100) substrates were used for electrochemical and structural characterization, respectively. Silver was found to be well distributed throughout the coatings, maintaining the films' composition in depth, while its diffusion to the electrolyte decreases as immersion time increases, stopping its release after 7 to 8 days of immersion. Electrochemical characterization revealed very stable films that have improved base material, without any diminished corrosion resistance due to the silver content.The authors are grateful to 3B's Research Group in Biomaterials, Biodegradables and Biomimetics for the ICP measurements and Prof. Isabel Leonor, PhD for her assistance. This research is partially sponsored by FEDER funds through the program COMPETE-Programa Operacional Factores de Competitividade and by Portuguese national funds through FCT-Fundacao para a Ciencia e a Tecnologia, under the project ANTIMICROBCOAT-PTDC/CTM/102853/2008. This work has also been supported by the Ministerio de Ciencia e Innovacion of Spain through the Consolider-Ingenio 2010 program (CSD2008-00023) and through the project RyC2007-0026

Water governance challenges at a local level: implementation of the OECD Water Governance Indicator Framework in the General Pueyrredon Municipality, Buenos Aires Province, Argentina

Considering that the current water crisis is largely a governance crisis, improving water governance will help to address current and future water challenges. Water governance is defined as the range of political, institutional and administrative rules, practices and processes through which decisions are taken and implemented, stakeholders can articulate their interests and have their concerns considered, and decision makers are held accountable for water management. The Water Governance Principles proposed by the Organisation for Economic Co-operation and Development (OECD) contribute to the creation of tangible public policies oriented toward effectiveness, efficiency, reliability and participation. The aim of this research is to apply the OECD Water Governance Indicator Framework at a local level and to identify gaps and challenges for water governance in the General Pueyrredon Municipality (GPM), Buenos Aires Province (BAP), Argentina. This framework was used as a diagnostic tool to assess water governance policy frameworks (what), institutions (who) and instruments (how). In general terms, there is a robust legal framework, there are enforcement institutions regarding water management and there is a good connection with them. However, the main challenges identified were in the ‘how’, since most of the instruments are partly or not implemented.Fil: Martín Velasco, María José. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; ArgentinaFil: Calderon, Gabriela. Ministerio de Ciencia. Tecnología e Innovación Productiva. Agencia Nacional de Promoción Científica y Tecnológica; Argentina. Universidad Nacional de Mar del Plata. Facultad de Arquitectura, Urbanismo y Diseño; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Lima, María Lourdes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Arquitectura, Urbanismo y Diseño. Instituto de Hábitat y Medio Ambiente; ArgentinaFil: Mantecón, Cecilia Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Massone, Hector Enrique. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentin

Nano-galvanic coupling for enhanced Ag+ release in ZrCN-Ag films: antibacterial application

The antibacterial properties of materials developed for medical devices with embedded silver nanoparticles are enhanced by controlling the release of silver ions. In this study, a simple experimental procedure for the augmentation of the silver ion release from ZrCN-Ag coatings is described. The silver nanoparticles are embedded in an amorphous carbon matrix within the ZrCN coatings, to create nano-galvanic couples between the silver and the carbon phases. The galvanic couple promotes the oxidation of silver, and consequently, increases the silver release. It is demonstrated that coatings with a lower silver content, but integrating amorphous carbon phases, can release similar or even a larger amount of Ag+ ions than those with higher Ag content having just ZrCN and Ag phases. The antibacterial tests demonstrate that coatings with silver nanoparticles encapsulated into amorphous phase reveal a larger bacterial zone of inhibition compared to samples with similar or lower silver content. However, it is shown that the antibacterial effect of the coatings not only depends on the ability for silver ion release, but also on the availability of silver nanoparticles on the surface.This research is partially sponsored by FEDER funds through the program COMPETE - Programa Operacional Factores de Competitividade and by Portuguese national funds through FCT-Fundacao para a Ciencia e a Tecnologia, under the projects ANTIMICROBCOAT - PTDC/CTM/102853/2008 and in the framework of the Strategic Projects PEST-C/ FIS/UI607/2011", UID/EMS/00285/2013 and SFRH/BD/80947/2011

Daily data of global vertical Insolation in the four cardinal orientations in Burgos, Spain

Daily data of Global, Diffuse and Beam Horizontal Insolation and Global Vertical (North, South, East and West orientations) insolation recorded in Burgos, Spain, are presented in this paper. Ten-minute irradiance data sets are collected over forty-five months in the experimental campaign to produce estimates of daily insolation levels. This data was derived in association with the article titled: “The PV Potential of Vertical Façades: a classic approach using experimental data from Burgos, Spain” (Díez-Mediavilla et al., in press) [1]. This dataset can be used to develop and test new solar radiation and daylight models and estimate the thermal load and lighting needs in buildings for the improvement of energy efficiency.Regional Government of Castilla y Leon (Junta de Castilla-León) (Ref. BU034U16) through the European Regional Development Fund, and from the Spanish Ministry of Economy, Industry and Competitiveness, under the I+D+i State Program Challenges for Society (Ref. ENE-2014–54601-R

Surface characterization of Ti-Si-C-ON coatings for orthopedic devices : XPS and Raman spectroscopy

Ti–Si–C–ON films were deposited by DC reactive magnetron sputtering and their chemical properties, biofilm formation and toxicity were characterized. Based on the films composition three different growth regimes were identified on the films; (I) N/Ti = 2.11 (high atomic ratio) and low oxygen content; (II) 0.77 ≤ N/Ti ≤ 1.86 (intermediate atomic ratio) and (III) N/Ti ≤ 0.12 (low ratio) and high oxygen content. The phase composition varied from mainly TiN on regime I to TiCN on regime 2 and titanium oxides on regime III. Taking into account the results of biological characterization (biofilm formation and cytotoxicity), it was possible to conclude that samples with a high TiN content (regime I) presented more favorable biocompatibility, since it was less prone to microbial colonization and also displayed a low cytotoxicity.The authors are grateful to Dr. Alicia Andres, Institut de Ciencia de Materiales de Madrid (ICMM-CSIC), for his assistance in carrying out the Raman spectroscopic analysis. The work was financially supported by the CRUP Institution (project "Accao No E-1007/08), and the Spanish Ministry of Science and Innovation (projects FUN-COAT CSD2008-00023, MAT2008-06618-C02 and Integrated action HP016-2007). This research is partially sponsored by FEDER funds through the program COMPETE- Programa Operacional Factores de Competitividade and by Portuguese national funds through FCT-Fundacao para a Ciencia e a Tecnologia, under the project PTDC/CTM/102853/2008

The PV potential of vertical façades: a classic approach using experimental data from Burgos, Spain

Potential photovoltaic (PV) production from vertical façades facing the four cardinal points of the compass are calculated from daily average vertical global insolation readings measured in Burgos, Spain. Ten-minute data sets are collected over forty-five months, from January 2014 to September 2017, in the experimental campaign to produce estimates of daily average insolation levels, from which the PV potential of the vertical surfaces was calculated. Given the scarcity of data on Global Vertical Insolation (GVI), the main sky-related variables were processed in four classic decomposition models (Isotropic, Circumsolar, Klucher, and Hay) to predict the insolation values. Both the experimentally measured GVI values and those calculated with the models were then compared using the statistical indicators RMSE and MBE. The results highlighted the economic viability of Building Integrated PhotoVoltaic (BIPV) facilities, even on the north-facing façades, in comparison with the horizontal facility at the same location.Regional Government of Castile and Leon (Junta de Castilla-León) (Ref. BU034U16) through the European Regional Development Fund, and from the Spanish Ministry of Economy, Industry and Competitiveness, under the I + D + i State Programme Challenges for Society (Ref. ENE-2014-54601-

Structure-property relations in ZrCN coatings for tribologic applications

ZrCN coatings were deposited by dc reactive magnetron sputtering with N2 flows ranging from 2 to 10 sccm in order to investigate the influence of the nitrogen incorporation on structure and properties. Information about the chemical composition was obtained by glow discharge optical emission spectroscopy and Rutherford backscattering spectroscopy. The evolution of the crystal structure studied by X-ray diffraction revealed the formation of a face-centred cubic ZrCN phase for N2 flows greater than 4 sccm. Additionally, the presence of an amorphous phase in the coatings deposited with the highest N2 flows could be evidenced by Raman spectroscopy and X-ray photoelectron spectroscopy. This phase can act as a lubricant resulting in a low coefficient of friction as shown in the conducted ball-on-disc tests. Nanoindentation measurements showed that coatings deposited with a 6 sccm N2 flow had the maximum hardness which also revealed the best performance in the conducted dry cutting tests.CRUP InstitutionSpanish Ministry of Science and InnovationChristian Doppler Research Associatio

CdTe Thin Films: Deposition Techniques and Applications

The II-IV semiconductor compound, CdTe, has suitable electrical and optical properties as photovoltaic and high-energy radiation sensor material. As an absorber material for thin-film-based solar cells, CdTe holds the potentiality to fabricate high-efficiency solar cells by means of low-cost technologies. This chapter presents a comprehensive review on the CdTe thin-film deposition techniques as well as on the several configurations for the solar cell structures that have led the best efficiency conversion. Current CdTe thin-film deposition techniques include sputtering, close spaced vapor transport (CSVT), chemical spray pyrolysis, and electrodeposition. These techniques have easily been adapted to deposit polycrystalline CdTe films on various flexible and rigid substrates. In regard to the device structure configuration, a variety of partner materials (transparent contact, optical window, buffer layer) were tested, and CdTe film thickness was varied to develop opaque and semitransparent devices by some techniques mentioned above. In this chapter, we will discuss about each technique used for CdTe thin-film deposition as well as its advantages and disadvantages