Search

Alumina (Al2O3) and titanium dioxide (TiO2) thin films were deposited by the atomic layer deposition technique on steel substrates used in the polymer injection molding industry. The modified steel...

In the piston ring-cylinder system, the surface topography is crucial to their tribological performance, emphasizing the relevance of the surface finishing processes. The present work studied the influence of different finishing processes in the surface roughness parameters of the coated compression piston rings. Three distinct surfaces’ finishing processes were used in the first approach: Option A, B, and C. Options D comprised the variation of different processing parameters. The piston rings with different surface topographies were tribologically evaluated using a tribometer developed explicitly for this industrial evaluation. Regarding the tribological performance, it was concluded that the use of the surface finishing processes fostered a decrease in the coefficient of friction. The surface finishing had also impacted the wear of the piston ring and in the counterbody. An increase in the piston rings’ surface roughness led to a rise in the surface's weight loss.

In the present work, a combination of conventional dc magnetron sputtering technique and gas condensation process was utilized to deposit a Ag–Au/a:C nanocomposite coating for application in stents. Quantitative evaluation of Ag+ release to the solution revealed a sharp increase of Ag+ releasing in the first 2 days of immersion, which continues but with a slower rate up to 14 days reaching a value close to 50 ppb. Atomic force microscopy surface morphology depicted that the roughness of the coating, Srms, increases after immersion from 5.86 to 14.22. X-ray photoelectron spectroscopy analysis showed two wide bands at 368.30 and 374.30 eV corresponding to the Ag 3d spin-orbit doublets for non-immersed coating. It was found that the Ag content drops to 5% of the initial concentration as the coating is exposed to artificial urine, due to the high affinity of Ag surface nanoparticles to solution anions. This Ag dissolution to artificial urine is followed by reprecipitating Ag salt clusters with a size less than 3 nm on the surface and the formation of a highly oxidized surface. The formation of the oxidation layer as a result of exposure of the coating to the solution is further confirmed by electrochemical impedance spectroscopy and polarization measurements. It was depicted the resistance of the coating increase from 1.80 to 2.86 MΩ as the coating is immersed into the solution for 14 days. The corrosion potential and corrosion current values collected from the polarization plot of the immersed coating were found to be −0.73 and 0.14, respectively, depicting the protecting character of the coating against the deteriorating solution. It was suggested that the formation of the oxidation layer on the coating surface seals the pores of the coating avoiding solution penetration to the substrate and consequently protecting it against corrosion.

Currently, biodiesel is marketed with mineral diesel constituting blends of biodiesel in accordance with the National Program for the Production and Use of Biodiesel (Law 11,097/05) but depending on the composition of biodiesel/diesel blends, there will be the physico-chemical properties of the mixtures. Among the properties, the density and kinematic viscosity very significantly with the changes in the compositions of the mixtures and therefore deserve to be high lighted, besides representing two important parameters monitored by National Petroleum, Natural Gas and Biofuel Agency (ANP) resolutions. In this article, the biodiesel produced from chichá oil was mixed with diesel in different proportions where the viscosities and densities of the blends were analyzed at different temperatures. With the values obtained, a study of the influence of these variables was carried out and a model of a surface was proposed to adjust the curves that varied as a function of the biodiesel concentration and the temperature. The model was validated with an unused curve during its construction and showed good ability to represent the relationship between the variables. Experimental data showed that the density and viscosity of the mixture increase with increasing percentage of biodiesel in the mixtures and decreased with increasing temperature for all biodiesel mixtures studied. Keywords: Biodiesel, Chichá, Modeling, Viscosity, Density

The present work aims to study the impact of O and N addition on Cr-sputtered coatings on plastic (polycarbonate, PC) used in automobile parts, as a promisor alternative for auto part metallization, while eliminating the usage of toxic hexavalent chromium. The coatings were deposited using DC magnetron sputtering from a single pure Cr target in a reactive atmosphere (N2 and/or O2). The deposition of the coatings was performed maintaining the total pressure constant and close to 1 Pa by tuning Ar pressure while reactive gases were added. The target current density was kept at JW = 20 mA·cm−2. Structural characterization revealed a mixture of α-Cr, δ-Cr, β-Cr2N, and CrN crystalline structures as well as amorphous oxides. The coating hardness ranged from 9 GPa for the CrON coating to 15 GPa for the CrN coating. All deposited coatings showed a particularly good interface adhesion; adjusting the amount of O and N made it possible to tune the optical properties of the Cr-based coatings as desired. The promising results open future industrialization of sputtered Cr-based coatings for automotive industries., This work was supported by COMPETE 2020 a Portuguese and European Union initiative through the Project POCI-01-0247-FEDER-042785, acronym “GREENCoat”. This research was sponsored by Norte2020, through European Social Fund (FSE), under the National Doctoral Program in “Surfaces Engineering and Protection”, NORTE-08-5369-FSE-000047. This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of Strategic Funding (co-financed via UIDB/00285/2020 and UIDB/04650/2020).

Due to their outstanding properties, carbon-based structures have received much attention from the scientific community. Their applications are diverse and include use in coatings on self-lubricating systems for anti-wear situations, thin films deposited on prosthetic elements, catalysis structures, or water remediation devices. From these applications, the ones that require the most careful testing and improvement are biomedical applications. The biocompatibility and antibacterial issues of medical devices remain a concern, as several prostheses still fail after several years of implantation and biofilm formation remains a real risk to the success of a device. Sputtered deposition prevents the introduction of hazardous chemical elements during the preparation of coatings, and this technique is environmentally friendly. In addition, the mechanical properties of C-based coatings are remarkable. In this paper, the latest advances in sputtering methods and biocompatibility and antibacterial action for diamond-based carbon (DLC)-based coatings are reviewed and the greater outlook is then discussed., This research is sponsored by national funds through FCT—Fundação para a Ciência e a Tecnologia, under the projects UIDB/00285/2020, UID/EMS/00285/2019 and UIDB/04650/2020, ATRITO-0 (co-financed via FEDER (PT2020) POCI-01-545 0145-FEDER-030446) and On-SURF (cofinanced via FEDER (PT2020) POCI-01-0247-FEDER-024521). Also, this work is supported by European Regional Development Fund (ERDF), through the Centro 2020 Regional Operational Programme under project CENTRO-01-0145-FEDER-000012-HealthyAging2020, and through the COMPETE 2020—Operational Programme for Competitiveness and Internationalization and Portuguese national funds via FCT-Fundação para a Ciência e a Tecnologia, under projects POCI-01-0145-FEDER-007440 and UID/NEU/04539/2019.

New leather treatment processes involving nanoparticles require new testing methods and procedures to evaluate their impact on human health. In the current work, the tribological properties of goat leather surfaces with sputter deposited Ti-Ag-O films were analyzed. A set of different polymer counter bodies was used to establish different tribological contact situations. A detailed analysis of the worn surfaces by scanning electron microscopy revealed details about the wear mechanisms ranging from abrasive to adhesive depending on the friction. Further, information about the formation of wear debris particles from the Ti-Ag-O films was obtained, in particular whether or not these particles were transferred to the counter body. The performed tests exemplify a possible testing procedure for leather treated with nanoparticles.

TiSiN(Ag) coatings with Ag contents ranging from 0 to 29 at.% were designed as promising materials to allow long term solid lubrication during dry machining operations. Here, we report the influence of Ag additions on the properties of TiSiN(Ag) films deposited by high power impulse magnetron sputtering- HiPIMS, working in deep oscillation magnetron sputtering mode – DOMS. Introduction of silver pellets on the target progressively increases the Ag concentration on the films, influencing the deposition rate, structure and morphology of the films. All the coatings display crystalline peaks assigned to a TiN fcc NaCl type structure. Ag additions to the reference TiSiN film, significantly broadens the TiN diffraction peaks and abruptly decreases the grain size of the TiN crystallites from 24 nm to 11–7 nm. Grain size was then found to be independent of the silver content on the films. Hardness and Young's modulus of the coatings decreased with increasing Ag additions mainly due to the increase of this soft phase on the microstructure. An increase in the peak power was observed when 6 at.% Ag was added which revealed a transition from a columnar to a very compact morphology, a decrease of the deposition rate and an increase of the lattice parameter for this coating. A reverse in the morphology is then perceived for the higher Ag concentration (29 at.%). Annealing treatment didn't present any significant changes in the structure/phase composition or mechanical properties of the coatings. Elemental maps and profiles allowed perceiving the formation of a very thin dual layer where a top Ag rich layer is formed due to the diffusion of silver from the Ag deficient TiSiN layer below.

Diamond-like carbon (DLC) coatings doped with Ag nanoparticles are promising materials for several application, as, for example, a biomaterial. In addition to their numerous properties, when doped with silver, DLCs can acquire antibacterial properties. In this study, Ag/a:C films were deposited by unbalanced magnetron sputtering. The dimension and distribution of silver nanoparticles in the carbon matrix were characterized before and after immersion in different liquid environments, ultra-pure water and NaCl (0.9%). Inductively coupled plasma-optical emission spectroscopy was used to quantify the Ag ions released from the film. Based on the aspect of Ag nanoparticles on the films surface, suggested by atomic force microscopy analysis, scanning electron microscopy was performed to access the dimension and the distribution of the nanoparticles at the surface and, then, to calculate the mass of Ag in the film, before and after exposure to both liquids. Agglomeration and coalescence of the nanoparticles in the film surface were studied and information about the segregation from the bulk to the surface was achieved, also confirmed by X-ray photoelectron spectroscopy analysis.

Accurate and sensitive identification of DNA mutations in tumor cells is critical to the diagnosis, prognosis and personalized therapy of cancer. Conventional polymerase chain reaction (PCR)-based methods are limited by the complicated amplification process. Herein, an amplification-free surface enhanced Raman spectroscopy (SERS) approach which directly detects point mutations in cancer cells has been proposed. A highly sensitive and uniform SERS substrate was fabricated using gold@silver core-shell nanorods, achieving an enhancement factor of 1.85 × 106. By combining the SERS-active nanosubstrate with molecular beacon probes, the limit of detection reached as low as 50 fM. To enable parallel analysis and automated operation, the SERS sensor was integrated into a microfluidic chip. This novel chip-based assay was able to differentiate between mutated and wild-type KRAS genes among a variety of other nucleic acids from cancer cells in 40 min. Owing to the simple operation and fast analysis, the SERS-based DNA assay chip could potentially provide insights into clinical cancer theranostics in an easy and inexpensive manner at the point of care.

The proposed work aims to functionalize leathers for footwear industry with antimicrobial properties based on AgTiO2 nanoparticles. The synthesis of nanoparticles was carried out by the hydrothermal method with significant advantages in terms of time, energy savings and low cost. Anatase TiO2 nanoparticles with dimensions below 10nm were obtained as observed by X-ray diffraction and transmission electron microscopy. Fourier transform infrared spectroscopy showed that the based structure of leather was not modified by the addition of the nanoparticles. The antimicrobial activity was evaluated and it was observed that Ag containing leathers gained antimicrobial activity. In addition, the nanoparticles were found to be non-cytotoxic. This achievement, by itself, should be quite appealing to the footwear industry as it could consist in a solid value-preposition given the commonness of fungal infections promoted by humidity, poor breathability and temperature that promote the expansion of the microflora of the skin., This research is sponsored by FEDER funds through theprogram COMPETE – Programa Operacional Factores de Competitividade and by the Portuguese Foundation for Science andTechnology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013, and UID/EMS/00285/2013 and in the framework of ERA-SIINN/0004/2013 project., info:eu-repo/semantics/publishedVersion

Bimetallic nanoparticles have gained attention in the last decade due to their unusual characteristics compared to monometallic counterparts. However, production of such particles with controlled morphologies and composition need to be explored and the mechanisms understood. In this work, we demonstrate a fast and simple process to obtain flower-like Zn-Fe (Zinc-Iron) nanoparticles (NPs) using a hybrid system based on the combination of conventional magnetron sputtering and a cluster beam source. The morphology and structure were characterized by Scanning transmission electron microscopy (STEM), while the chemical composition was evaluated by simultaneous acquisition of Energy-dispersive X-ray spectroscopy (EDS) and Electron energy loss spectroscopy (EELS). Besides, molecular dynamic simulations were used to model the nanoparticle collisions during the simultaneous production, revealing the formation mechanisms of the flower-like nanoparticles., The authors thank the financial support by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020 and by project NANOXYPACK cofinanced via FEDER (PT2020) POCI-01-0145-FEDER-030789., info:eu-repo/semantics/publishedVersion

Zirconium oxynitride (Zr(O)N) and Copper-Zirconium oxynitrides (Cu-Zr(O)N) were deposited by a DC reactive magnetron sputtering technique on stainless steel substrates. A duty cycle controller was used to obtain different oxygen contents in the developed films and a chemical activation procedure was carried out to obtain copper oxides. The samples were chemical and structurally characterized by SEM, EDS, XRD and XPS. Additional functional features were evaluated according to colour variation and inhibition halo tests. Zr(O)N and Cu-Zr(O)N surfaces showed a wide colour variation from golden to black tones, progressing through intermediate tones such as purple, blue and bluish grey. An antibacterial effect was only obtained after the chemical activation of Cu-ZrON-DC100, which showed a Zr(O)N matrix incapable of catching more oxygen from deposition. After, with the additional availability of O2- ions, the Cu present in the coating reacted with these ions forming CuO. The antibacterial mechanism was associated with the aforementioned characterizations and ICP-OES spectroscopy. The Cu2+ ions release had no influence on the antibacterial effect although the presence of CuO was decisive in obtaining an antibacterial behaviour. The acquired results demonstrated a potential multifunctionality of Cu-Zr(O)N coatings, joining an aesthetical surface with an antibacterial effect., This research is sponsored by FEDER funds through the COMPETE program - Competitive Factors Operational Program - and by national funds through FCT - Foundation for Science and Technology - under the scope of the strategic funding of co-financed via UIDB/00285/2020 and UIDB/04650/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte, On-SURF (co-financed via FEDER (PT2020) POCI-01-0247-FEDER 546024521; The authors also thank the financial support in the framework of HEALTHYDENT - POCI-01-0145-FEDER-030708) and ATRITO-0 (co-financed via FEDER (PT2020) POCI-01- 0145-FEDER-030446., info:eu-repo/semantics/publishedVersion

A previously developed fiber-based polyester (PES) stent, with mechanical properties comparable to commercial nitinol stents, was coated with metallic silver (Ag0) and silver oxides (AgxO) thin films through direct current (DC) magnetron sputtering. Ag0 and AgxO coatings provide antimicrobial properties to the stents to minimize the occurrence of coronary stent infections. Nevertheless, the stent interacts with the atmosphere and then with the biological fluids and may lead to the generation of silver species with diminished antimicrobial efficiency and/or prone to induce cytotoxicity. Therefore, stent coating nanostructures aged 3 months were thoroughly analyzed by X-ray photoelectron spectroscopy (XPS) and their antimicrobial and cytotoxicity properties were assessed. Aging led to the presence of silver carbonate and bicarbonate as well as chemisorbed oxygen species in Ag0 and AgxO coatings. Bactericidal efficacy was tested against an important nosocomial bacterium, particularly associated to indwelling devices: Staphylococcus epidermidis. Aged Ag0 and AgxO coating presented a Log reduction of 1 and 2 at their surface, respectively. However, aged stents were able to induce a Log reduction of 2 (Ag0) and 4 (AgxO) on the surrounding medium. Only aged AgxO stent was able to provide a mild reduction of the bacterium at its surface and a clear antimicrobial effect (Log reduction &gt, 3) within its vicinity. More importantly, both aged Ag0 and AgxO stents were shown to be compatible with fibroblasts cells indicating that they can be safely used as indwelling devices, despite the aging effect.

Implant surfaces with cytocompatible and antibacterial properties are extremely desirable for the prevention of implant's infection and the promotion of osseointegration. In this work, both micro-arc oxidation (MAO) and DC magnetron sputtering techniques were combined in order to endow tantalum-based surfaces with osteoblastic cytocompatibility and antibacterial activity. Porous Ta2O5 layers containing calcium (Ca) and phosphorous (P) were produced by MAO (TaCaP) to mimic the bone tissue morphology and chemical composition (Ca/P ratio close to 1.67). Furthermore, zinc (Zn) nanoparticles were deposited onto the previous surfaces by DC magnetron sputtering without or with an additional thin carbon layer deposited over the nanoparticles (respectively, TaCaP-Zn and TaCaP-ZnC) to control the Zn ions (Zn2+) release. Before osteoblastic cell seeding, the surfaces were leached for three time-points in PBS. All modified samples were cytocompatible. TaCaP-Zn slightly impaired cell adhesion but this was improved in the samples leached for longer immersion times. The initial cell adhesion was clearly improved by the deposition of the carbon layer on the Zn nanoparticles, which also translated to a higher proliferation rate. Both Zn-containing surfaces presented antibacterial activity against S. aureus. The two surfaces were active against planktonic bacteria, and TaCaP-Zn also inhibited sessile bacteria. Attributing to the excellent in vitro performance of the nanostructured Ta surface, with osteoconductive elements by MAO followed by antimicrobial nanoparticles incorporation by magnetron sputtering, this work is clearly a progress on the strategy to develop a new generation of dental implants.

Tantalum oxide (Ta2O5) nanostructures exhibit outstanding electrical and optical properties, as well as, high chemical resistance and stability. These materials have great potential for biomedical, catalysis, semiconductors and energy applications due to their large surface area and high specific charge, when arranged in nanoporous or nanotubular morphologies. In order to obtain these structures, an anodization process, which is inexpensive, reproducible and easy to scale up, is used. Yet, depending on the anodization conditions, the formation of a nanoporous or nanotubular layer is difficult to stabilize during the anodization process. In this regard, anodized tantalum oxide nanostructures were produced to understand the effect of the anodization conditions, including electrolyte concentration, potential and time. The nanopores or nanotubes morphologies, their chemical composition and structure were investigated by FIB-SEM, double-corrected TEM-STEM and EDS. We found that it is necessary to have high acid concentrations (mixture of H2SO4 with HF) to be able to form nanoporous or nanotubular structures. Despite the capacity of HF to dissolve and create anodic oxide nanostructures, the amount of H2SO4 concentration in the mixture is very important, leading to a dimple morphology. Furthermore, the increase of the anodization potential/electrical field clearly leads to an increase in the dimples diameter., This research is sponsored by FEDER funds through the program COMPETE -Programa Operacional Factores de Competitividade and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020, and UID/EMS/00285/2020 and with a PhD fellowship SFRH/BD/98199/2013.The authors thank the financial support in the framework of HEALTHYDENT -POCI-01-0145-FEDER-030708 and PTDC/CTM-NAN/4242/2014 projects.This work was supported by FCT, through IDMEC, under LAETA, project UIDB/50022/2020.The authors would like to acknowledge that this project has received funding from the EU Framework Programme for Research and Innovation H2020, scheme COFUND -Co-funding of Regional, National and International Programmes, under Grant Agreement 713640.

The purpose of this work is the development of Ag/a:C and Ag-Au/a:C coatings for ureteral stents, to provide them with antimicrobial characteristics. Silver was selected due to the well-known antibacterial properties, while gold was included to assess its capacity to accelerate the silver ion release forming a galvanic couple between Au and Ag. Thus, the metallic (Ag) and bimetallic clusters (Ag/Au) were produced by three different configurations: i) unbalanced magnetron sputtering (conventional sputtering), (ii) plasma gas condensation process and by (iii) a combination between both previous approaches. Coatings with Ag/Au bimetallic clusters were characterized by transmission electrons microscopy (TEM) in order to study the arrangement (alloy, core-shell and galvanic couple) of these particles in the carbon matrix. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to quantify the Ag ions released through artificial urine from the different coatings deposited on thermoplastic polyurethane (TPU) tape (one of the materials used in the ureteral stent manufacture). Then, the antibacterial and cytotoxicity properties of Ag and Ag-Au/a:C coatings were evaluated. TEM shows that a biphasic structure was not detected, thus not allowing to anticipate the establishment of a galvanic couple. The ICP-OES results demonstrate that the silver ionization is mainly a function of the amount of silver incorporated in the amorphous carbon (a:C) matrix, and the formation of bimetallic alloy has a detrimental effect on release of the silver ions. The antibacterial activity was regulated by the silver ionization mechanisms since the coatings with higher Ag release had a higher antibacterial activity., This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the projects: PTDC/CTM-NAN/4242/2014, under the framework of the Strategic Funding; UIDB/04650/2019 and UIDB/04469/2020; BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020; CEMMPRE - UID/EMS/00285/2019 [co-financed via FEDER and FCT (COMPETE)]; ATRITO-0 (co-financed via FEDER (PT2020) POCI 01-0145-FEDER-030446 and FCT (PIDDAC)); On-SURF (co-financed via FEDER (PT2020) POCI-01-0247-FEDER-024521); IDMEC, under LAETA, project UID/EMS/50022/2019., info:eu-repo/semantics/publishedVersion

Interest in nanoporous tantalum oxide (Ta2O5) has been increasing due to its high variety of applications, from protective coatings, photocatalysts to biomedical devices. Anodization is a surface modification technique, which is inexpensive, versatile, easily scalable and widely used to produce these nanostructures. In this study, Ta2O5 nanoporous surfaces were produced by anodization in HF-free electrolyte composed of ethylene glycol, water and ammonium fluoride (NH4F) with different anodization parameters (electrolyte concentration, applied potential and time). The surface morphology of each sample was investigated by scanning electron microscopy (SEM) and the sample with the more uniform porous nanostructure was characterized in terms of cross-section morphology, chemical composition and crystalline structure. The concentration of NH4F and applied potential demonstrated a significant impact on current-density-time curve, and thereafter in surface morphology. Multiple thin porous nanolayers were formed under strong electrochemical conditions (very high current density and electrolyte temperature). Through chemical analysis, it was possible to detect the presence of fluoride, which is consistent with an amorphous Ta2O5 layer with fluoride ions incorporation. Thereby, managing the electrochemical conditions is crucial to control the morphology of an anodic Ta2O5 layer., This research was supported by Norte2020, through European Social Fund (FSE), under the National Doctoral Program in “Surfaces Engineering and Protection”, NORTE-08-5369-FSE-000047. The authors also thank the financial support by Portuguese Foundation for Science and Technology (FCT) in the framework of the HEALTHYDENT (co-financed via FEDER (PT2020) POCI-01-0145-FEDER-030708 and FCT (PIDDAC)), On-Surf (co-financed via FEDER (PT2020) POCI-01-0247-FEDER-024521) and Strategic Funding (co-financed via UID/FIS/04650/2019 and FCT) projects.

Aiming investigated the pyrolysis of the agricultural waste known as cassava stump, the portion of the plant to which the tuberous roots and aerial parts of the plant are attached, this study had as objective to produce biochars from cassava stump by conducting vacuum pyrolysis at 400, 500, or 600 °C. The biochars were characterized by proximate analysis, thermogravimetric analysis, Fourier-transform infrared absorption spectroscopy, X-ray diffraction, scanning electron microscopy, and nitrogen adsorption. Adsorption affinity tests were performed with four different dyes: methylene blue, basic fuchsin, acid fuchsin, and alizarin. Biochar obtained at 500 °C, heating rate of 20 °C.min−1, and 90 min of residence at the final temperature, had 22% higher fixed carbon content as compared to the other biochars and 3.16 times greater fixed carbon content than the original cassava stump. This biochar showed the best adsorption capacity (0.0679 mmol/g) and percentage of removal (87.6%) of methylene blue dye...

In this work, magnetron sputtered CrNx thin films with nitrogen concentrations ranging from 17 to 30 at.% were deposited on plasma activated ABS. Two sets of thin films were obtained by varying the N-2 flow inside the vacuum chamber (series #1) and the deposition time (series #2). The polymer samples were also subjected to plasma treatment in Ar prior to the CrNx thin films' deposition, in order to enhance the adhesion. The fundamental microstructural, chemical and physical properties, as well as the electrochemical and adhesion behavior of the CrNx thin films, were assessed by SEM, XRD, 3D profilometry, RAMAN, colorimetry, OCP measurements and cross-cut tape test. Main results show that high-quality CrNx films with a low percentage of defects were obtained. The CrNx film sputtered with 3 sccm N-2 for 20 min was considered to possess the most appropriate brightness, color, electrochemical stability and interfacial adhesion to fit the end-user requirements. Magnetron sputtering is thus a promising alternative to the hazardous chrome plating for an effective metallization of ABS., This work was developed within the scope of the project POCI-01-0247-FEDER-003493 co-financed by FEDER through the POCI program and project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT ref. UID/CTM/50011/2013), financed by national funds through FCT and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement., info:eu-repo/semantics/publishedVersion

The oblique angle deposition (OAD) is a versatile and easily controllable method appropriate for the production of nanoporous structures with pores in nanometric range and high surface area. In this study, aluminum thin films were deposited by sputtering on both commercial and homemade porous aluminum oxide substrates, tilted 85° and 89°. The morphology of substrates and the shadowing effect created by the OAD led to the deposition of densely packed columnar Al thin films with surface pores which sizes range between 19 and 75 nm depending on the substrate, tilt angle, time of deposition and power density. Focused ion beam (FIB) nanotomography allowed the 3D reconstruction of the whole nanoporous structures, in which the substrate, the thin film and the interface could be easily observed. Moreover, these results showed the hourglass-like shape of pores in the Al thin films, as well as the pores interconnectivity and the existence of open porosity that ensures the passage of the gas/liquid flow through the nanoporous structure. This study provides further insights into the production patterns of nanoporous structures by OAD, with a potential application in nanofiltration systems able to filter nanoparticles, which are often found in industrial environments and can represent a risk for human health and environment.

WS2 self-lubricant coatings were fluorine-carbon alloyed to improve the load-bearing capacity, decrease the friction and, further, explore the water/oil wettability behaviour. The WS-C/F coatings were deposited by magnetron sputtering using an Ar/CF4 mixture. Up to a certain CF4 flow rate, F was effectively incorporated in the coatings (maximum of 9.5 at.%) which led to both compactness and hardness increase. Further CF4 flow rate increase led to fluorine content vanishing, while the oxygen and carbon contents increased, then hindering the mechanical properties. XPS results revealed that F and O are chemically bonded to W/S or W/C phases. The tribological performance evaluated at room temperature showed that, sporadically, the friction coefficient of the coating with 9.5 at.% F content reached lower values than WS2 (COF = 0.04 against 0.05). Meanwhile, when it was tested at 200 °C, the same coating showed lower COF values in the overall test (0.016 compared to 0.030), this attributed to the higher interplanar distance due to F insertion in the WS2 structure confirmed by XRD. F incorporation seemed to decrease the coating surface roughness and increased its hydrophilicity, with no effect on the oleophilicity. This study presents a further insight on the understanding of the fluorine doping of sputtered WS2 coatings for potential mechanical application.

Coated ureteral stents must be placed in the human body without hurting the body tissue and, simultaneously, support the application without degrading the top active layer. In this work Ag clusters incorporated in a:C (Ag/a:C) matrix were produced by plasma gas condensation process. After optimizing some deposition parameters, as cluster source pressure and power density, two different clusters sizes were obtained 11 ± 2 nm using cluster source pressure of 100 Pa, and a bimodal size using cluster source pressure of 200 Pa (31 ± 22 nm and 260 ± 135 nm). Ag/a:C coatings showed a total adhesion to substrate, without delamination of the film, even after a month of immersion in distilled water. The friction coefficient of the coatings and the uncoated reference were determined and show a reduction from 0.22 for the reference stent to 0.12 for the Ag/a:C coated stents produced at 100 Pa and to 0.16 for the Ag/a:C coated stents produced at 200 Pa.

In order to make bio-based packaging materials competitive in comparison to petroleum-based one, some of their properties need to be improved, among which gas permeability is of crucial importance. Thus, in this work, carbon-based coatings were applied on chitosan-based films by radiofrequency reactive magnetron sputtering aiming to improve their barrier properties. Chemical and morphological properties were evaluated in order to determine the effect of the coatings on the chemical structure, surface hydrophobicity and barrier properties of the system. Chemical analysis, performed by electron energy loss spectroscopy and Fourier transform infrared spectroscopy, suggests similar chemical characteristics among all coatings although higher incorporation of hydrogen as the acetylene flux increases was observed. On the other hand, scanning transmission electron microscopy revealed thatthe porosity ofthe carbon layer can be tailored by the acetylene flux. More importantly, the chitosan oxygen permeability showed a monotonic reduction as a function of the acetylene flux. This study opens up new opportunities to apply nanostructured coatings on bio-based polymer for enhanced oxygen barrier properties., This research is sponsored by FEDER funds through the program COMPETE – Programa Operacional Factores de Competitividade and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013, and UID/EMS/00285/2013 and in the framework of ERA-SIINN/0004/2013 and PTDC/CTM-NAN/4242/2014 projects. This research was supported by Norte Regional Operational Program 2014–2020 (Norte2020) through the European Regional Development Fund (ERDF) Nanotechnology based functional solutions (NORTE-01-0145-FEDER-000019)., info:eu-repo/semantics/publishedVersion

Previous studies have shown both Ta and TaeO to be bioactive, rapidly forming a strongly-bonded surfaceadherent layer of bone-like hydroxyapatite (HAp) when immersed in simulated body fluid (SBF). Consequently, Ta and TaeO coatings are promising for the surface-modification of Ti or stainless steel endodontic endosseous implants, being conducive to a reduction in the risk of developing post-operatory infection and/or peri-implantitis disease. That said, few studies have investigated the effect of Ta or TaeO coatings on such phenomena as cell activation, adhesion, and proliferation. To that effect, Ta, and TaeO films were deposited onto type 316L stainless steel (SS 316L) substrates by reactive DC magnetron sputtering, after which their biological response was evaluated following co-incubation with the murine macrophage-like cell line RAW 264.7. Cell morphology after adhesion was observed by SEM, whereas cell viability and proliferation were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. Lastly, inflammatory response was assessed by quantification of the cytokines interleukin-6 (IL-6) and interleukin-10 (IL-10). In terms of phase composition, Ta showed a mixture of the α-Ta and β-Ta phases, whereas TaeO showed a nanocrystalline structure. Moreover, a decrease in average roughness (Ra) from 21 nm to 7 nm was observed between Ta and TaeO, accompanied by a decrease in water contact angle (θW) from 106° to 83°. In vitro studies showed that cells exhibited significantly better adhesion to Ta, in comparison with both TaeO and SS 316L. Furthermore, both Ta and TaeO were shown to be non-cytotoxic, with Ta outperforming TaeO in terms of relative cell viability, both at 24 h and 48 h. Lastly, both Ta and TaeO showed vastly inferior IL-6 and IL-10 levels to those obtained for cells treated with bacterial lipopolysaccharides (LPS)—prompting the conclusion that the coatings do not in any way induce an inflammatory response from macrophage cells., This research was sponsored by FEDER funds, through the program COMPETE – Programa Operacional Factores de Competitividade; and by the Portuguese Foundation for Science and Technology (FCT), in the framework of the Strategic Funding UID/FIS/04650/2013, UID/EMS/ 00285/2013, and UID/BIA/04050/2013, as well as the ERA-SIINN/ 0004/2013 and PTDC/CTM-NAN/4242/2014 projects., info:eu-repo/semantics/publishedVersion

Aiming to improve the protection of human health and the environment, REACH regulation was enforced across European Union, accelerating the need to find alternative solutions to the electrodeposition processes of hexavalent chromium employed in several industrial applications. Electroplated chromium coatings are widely used due to their physical and mechanical properties that allow a longer service life of products that usually fail due to wear. Minting is one of those applications where good mechanical and tribological properties are required and where hard chromium has an important usage without being outmatched by other coatings. This study presents the development of an alternative coating to hard chromium with outstanding mechanical properties, in particular high resistance to cyclic loads. Cr(Al,Si)N coatings have been produced by reactive DC magnetron sputtering. Focusing on mechanical properties, an increase in the hardness was observed with the consecutive addition of elements to the base matrix (CrN), ranging from ≈10 GPa in CrN coatings up to ≈17 GPa for the CrAlSiN coatings. In nano-impact tests, CrAlN coatings had the best performance and no crack events by fatigue were observed by SEM after 50 impacts, with load maximum 20mN, with an estimated maximum contact pressure of 1.5 GPa much higher than the one requested for coinage. The fatigue wear was governed by the H/E ratio and plasticity index showing that Cr(Al,Si)N coatings deposited by reactive magnetron sputtering can be considered excellent candidates for cyclic loading, as in minting applications.

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.

Magnetron sputtering has been employed for several decades to produce protective and multi-functional coatings, thanks to its versatility and ability to achieve homogeneous layers. Moreover, it is suitable for depositing coatings with very high melting points and that are thermodynamical unstable, which is difficult to accomplish by other techniques. Among these types of coating, transition metal (Me) carbides/nitrides (MeC/N) and amorphous carbon (a-C) films are particularly interesting because of the possibility of tailoring their properties by selecting the correct amount of phase fractions, varying from pure MeN, MeC, MeCN to pure a-C phases. This complex phase mixture can be even enhanced by adding a fourth element such Ag, Pt, W, Ti, Si, etc., allowing the production of materials with a large diversity of properties. The mixture of phases, resulting from the immiscibility of phases, allows increasing the number of applications, since each phase can contribute with a specific property such as hardness, self-lubrication, antibacterial ability, to create a multifunctional material. However, the existence of different phases, their fractions variation, the type of transition metal and/or alloying element, can drastically alter the global electrochemical behaviour of these films, with a strong impact on their stability. Consequently, it is imperative to understand how the main features intrinsic to the production process, as well as induced by Me and/or the alloying element, influence the characteristics and properties of the coatings and how these affect their electrochemical behaviour. Therefore, this review will focus on the fundamental aspects of the electrochemical behaviour of magnetron-sputtered films as well as of the substrate/film assembly. Special emphasis will be given to the influence of simulated body fluids on the electrochemical behaviour of coatings., This research is sponsored by FEDER funds through the program COMPETE–Programa Operacional Factores de Competitividade and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2019, and UID/EMS/00285/2013 and in the framework of PTDC/CTM-NAN/4242/2014 and PTDC/NAN-MAT/30789/2017. The authors also thank the financial support by the Portuguese Foundation for Science and Technology (FCT) in the framework of the HEALTHYDENT (co-financed via FEDER (PT2020) POCI-01-0145-FEDER-030708 and FCT (PIDDAC) and the NANOXYPACK POCI-01-0145-FEDER-030789 projects. This research was supported by Norte Regional Operational Program 2014-2020 (Norte2020) through the European Regional Development Fund (ERDF) Nanotechnology-based functional solutions (NORTE-01-0145-FEDER-000019) and through European Social Fund (FSE), under the National Doctoral Program in “Surfaces Engineering and Protection”, NORTE-08-5369-FSE-000047. The authors would like to acknowledge the EU Framework Programme for Research and Innovation H2020, scheme COFUND – Co-funding of Regional, National and International Programmes, under Grant Agreement 713640. The CENTRO Program is also acknowledged through the projects MATIS - CENTRO-01-0145-FEDER-000014 and On-Surf - POCI-01-0247-FEDER-024521.

The production of Ta1-xOx coatings has attracted a lot of attention due to their wide variety of industrial applications. Nonetheless, to properly control the functional properties of these coatings, a good understanding of their structural properties must be achieved. Ta1-xOx phases have structural similarities since they are formed by the distortion of the body centered cubic (bcc) Ta structure and, therefore, a clear and unequivocal identification of the crystalline phases is not trivial. In this regard, this work proposes a theoretical and experimental study to understand the evolution of the structural and the elastic properties of Ta-based coatings. The coatings were deposited by magnetron sputtering as a function of oxygen content and characterized by EPMA (electron probe microanalysis), XRD (X-ray diffraction), STEM (scanning transmission electron microscopy) and SAW (surface acoustic waves). The results demonstrate the formation of a bcc alpha-Ta phase in the non-reactive Ta coating, which transitions to a mixture of crystalline tantalum and tantalum oxide phases for low oxygen concentrations while amorphous phases are observed for high oxygen levels. Ab-initio calculations of different Ta-O phases are in good agreement with the experimental results and reveal that the oxygen addition to the metallic Ta phase, leads to a distortion of the Ta crystal structure, causing a decrease in density and an increase of the elastic constants., This research is sponsored by FEDER funds through the program COMPETE -Programa Operacional Factores de Competitividade and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013, and UID/EMS/00285/2013 and with a PhD fellowship SFRH/BD/98199/2013. The authors also thank the financial support in the framework of ERA-SIINN/0004/2013 and PTDC/CTM-NAN/4242/2014 projects.

This work aims to study the electrochemical and the corrosion resistance of amorphous carbon coatings with metallic (Ag) and bimetallic (Ag Au) nanoparticles deposited on stainless steel 316L by dc magnetron sputtering technique. These coatings were designed to coat ureteral stents and, accordingly, the Ag release measurement, morphological and electrochemical investigations were performed on the coatings immersed into artificial urine solution during 14 days to imitate the ureter electrolyte (urine) where the stents are inserted. These coatings are intended for insertion into the human body; then, in addition to the biocompatibility, they should not corrode since the resulting products can cause different adverse reactions. The Ag release study showed that the concentration of Ag+ release from the Ag-doped coating is much higher than the Ag Au one over the measured time. Moreover, scanning electron microscopy analysis on the immersed and non-immersed coatings supported the Ag ion release assessment. From STEM analysis, the formation of Ag Au nanoalloys in a wide size distribution was confirmed. Additionally, the electrochemical characteristics and corrosion resistance behavior of the coatings were investigated in artificial urine solution over immersion time by electrochemical impedance spectroscopy. The Nyquist plots were successfully fitted with a proper equivalent circuit based on a two-layer model representing a porous outer layer and a barrier inner layer for the coatings. The electrochemical measurements revealed that the coating doped with Ag Au nanoparticles has improved corrosion resistance and less porosity compared to the Ag-doped one. The enhanced protective feature of the Ag-Au/a:C coatings can be attributed to the formation of Ag Au nanoalloys that helps to block the solution penetration into the substrate.

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.

Biofilm formation has been pointed as a major concern in different industrial applications, namely on biomedical implants and surgical instruments, which has prompted the development of new strategies for production of efficient antimicrobial surfaces. In this work, nano âgalvanic couples were created to enhance the antibacterial properties of silver, by embedding it into amorphous carbon (a-C) matrix. The developed Ag/a-C nanocomposite coatings, deposited by magnetron sputtering, revealed an outstanding antibacterial activity against S.epidermidis, promoting a total reduction in biofilm formation with no bacteria counts in all dilution. The open circuit potential (OCP) tests in 0.9% NaCl confirmed that a-C shows a positive \OCP\ value, in contrast to Ag coating, thus enhancing the ionization of biocidal Ag+ due to the nano-galvanic couple activation. This result was confirmed by the inductively coupled plasma-optical emission spectroscopy (ICP-OES), which revealed a higher Ag ionization rate in the nanocomposite coating in comparison with the Ag coating. The surface of Ag/a-C and Ag coatings immersed in 0.9% NaCl were monitored by scanning electron microscopy (SEM) over a period of 24 hours, being found that the Ag ionization determined by ICP-OES was accompanied by an Ag nanoparticles coalescence and agglomeration in Ag/a-C coating., AcknowledgmentsThis research is sponsored by FEDER funds through the programCOMPETE-Programa Operacional Factores de Competitividade –by national funds through FCT - Fundação para a Ciência e a Tecnologia, in the framework of the Strategic Projects PEST-C/FIS/UI607/2013, and PEst-C/EME/UI0285/2013, and with PhDfellowships SFRH/BD/82472/2011 and SFRH/BD/80947/2011.

Ag and AgxO thin films were deposited by non-reactive and reactive pulsed DC magnetron sputtering, respectively, with the final propose of functionalizing the SS316L substrate with antibacterial properties. The coatings were characterized chemically, physically and structurally. The coatings nanostructure was assessed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), while the coatings morphology was determined by scanning electron microscopy (SEM). The XRD and XPS analyses suggested that Ag thin film is composed by metallic Ag, which crystallizes in fcc-Ag phase, while the AgxO thin film showed both metallic Ag and Ag-O bonds, which crystalize in fcc-Ag and silver oxide phases. The SEM results revealed that Ag thin film formed a continuous layer, while AgxO layer was composed of islands with hundreds of nanometers surrounded by small nanoparticles with tens of nanometers. The surface wettability and surface tension parameters were determined by contact angle measurements, being found that Ag and AgxO surfaces showed very similar behavior, with all the surfaces showing a hydrophobic character. In order to verify the antibacterial behavior of the coatings, halo inhibition zone tests were realized for Staphylococcus epidermidis and Staphylococcus aureus. Ag coatings did not show antibacterial behavior, contrarily to AgxO coating, which presented antibacterial properties against the studied bacteria. The presence of silver oxide phase along with the development of different morphology were pointed as the main factors in the origin of the antibacterial effect found in AgxO thin film. The present study demonstrated that AgxO coating presented antibacterial behavior and its application in cardiovascular stents is promising., The authors acknowledgments the financial support of FCT-Fundacao para a Ciencia e Tecnologia through grants: SFRH/BD/90321/2012 and SFRH/BD/82472/2011.Also thank support by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2014, and projects ERA-SIINN/0004/2013 and the project Matepro-Optimizing Materials and Processes, ref. NORTE-07-0124-FEDER-000037", co-funded by the "Programa Operacional Regional do Norte" (ON.2-O Novo Norte), under the "Quadro de Referencia Estrategico Nacional" (QREN), through the "Fundo Europeu de Desenvolvimento Regional" (FEDER).

In the sensors field, titanium based coatings are being used for the acquisition/application of electrical signals from/to piezoelectric materials. In this particular case, sensors are used to detect dynamic mechanical loads at early stages after intervention of problems associated with prostheses implantation. The aim of this work is to select an adequate electrode for sensor applications capable, in an initial stage to avoid bone cell adhesion, but at a long stage, permit osteointegration and osteoinduction. This work reports on the evaluation of osteoblast MC3T3-E1 cells behavior in terms of proliferation, adhesion and long-term differentiation of two different systems used as sensor electrodes: Ti1-xAgx and Ag-TiNx deposited by d.c. and pulsed magnetron sputtering at room temperature on poly(vinylidene fluoride) (PVDF). The results indicated an improved effect of Ag-TiNx electrodes compared with Ti1-xAgx and TiN, in terms of diminished cell adhesion and proliferation at an initial cell culture stage. Nevertheless, when cell culture time is longer, cells grown onto Ag-TiNx electrodes are capable to proliferate and also differentiate at proper rates, indicating the suitability of this coating for sensor application in prostheses devices. Thus, the Ag-TiNx system was considered the most promising electrode for tissue engineering applications in the design of sensors for prostheses to detect dynamic mechanical loads., The author S.M.M. gratefully acknowledge the funding form the Portuguese national funds through the FCT-Fundacao para a Ciancia e a Tecnologia, (grant SFRH/BD/71259/2010). Also thank support by FEDER through the COMPETE Program and by the Fundacao para a Ciencia e a Tecnologia (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2014. J.L.G.R. and P.R acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2013-46467-C4-1-R and MAT2012-383.59-C03-01 project (including the FEDER financial support). CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program. CIBER actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Found. The authors thank financial support from the Basque Government Industry Department under the ELKARTEK Program. S.L.M. thanks the Diputacion de Bizkaia for financial support under the Bizkaia Talent program.

Self-lubricant coatings offer an opportunity to increase tool lives in dry machining operations for hard-to-cut materials. In this work, TiSiN(Ag) coatings were deposited to assess the influence of silver in the tribological behaviour at high temperatures. Two types of counterparts were used: 6 mm diameter Al2O3 and TiAl6V4 balls. RT tests conducted against Al2O3 balls showed that silver slightly decreases the friction but deteriorates the wear resistance. Wear resistance is improved when the temperature is increased to 600 °C, when compared to RT tests. Tribology tests against TiAl6V4 balls showed that silver has a beneficial effect in the reduction of friction and wear. Additionally, silver hinders the adhesion of material to the wear track. Temperature also plays an important role in propelling the effects of silver.

PVD coatings are widely used in the automotive industry for tribological purposes. In heavy-duty diesel engines, piston rings represent a challenging component concerning its tribological performance. Top piston rings were designed as an additional part with a supporting role in the sealing or prevention of gas leakages from the combustion chamber. Several sudies have been published proposing metal nitride coatings for the piston ring's functional surface. CrN coatings are among those most frequently proposed, but regularly using magnetron sputtering as the predefined deposition method. In a large-scale production framework, different deposition methods with improved deposition rates must be adopted. Cathodic arc deposition is currently widely implemented in several industries, such as in the automotive one. Although this technique is consolidated in the industrial environment, the deposition process and parameters are continuously under optimization. In the present study,two different CrN coatings deposited on the piston ring's functional surface are studied. Using other deposition conditions, two distinct morphologies are achieved in the coating layer: a denser structure (CrN-A) and a columnar structure (CrN-B). Those coatings were tested using a locally developed test rig, adapted to test the piston rings under conditions close to the real engine operation. The microstructure and mechanical properties of the CrN-A and CrN-B coatings were evaluated using X-ray diffraction and micro-indentation. The surface morphology and wear mechanism were characterized using SEM and EDS techniques before and after to perform the wear and friction tests.

Additive manufacturing (AM) is a hot topic nowadays, having a first order in importance in research trends, improving existent technologies and carrying them further. AM can be applied to ceramics, which have importance in current technologies. Their capability to maintain functional properties for long time periods, combined with the easiness to process and the abundance of raw materials, make them a fundamental part of mankind development. Within ceramics, stoneware has a wide range of uses but in some conditions, it can be affected by biofouling. Ti(O)N and Ag-Ti(O)N coatings over 3D printed stoneware, were presented as multifunctional solution, linking aesthetical and antimicrobial properties. Films were developed by reactive direct current (DC) magnetron sputtering and characterized physical, chemical and morphologically, as well as regarding their colour variation. Moreover roughness, wettability, antibacterial and antibiofouling were also evaluated. The results revealed that the Ag doped coatings (with or without oxygen addition) had an enhanced multifunctionality compared to control samples (without Ag). Ag nanoparticles addition created a surface with potential antibacterial and antibiofouling activities, in order to resist outdoors and aqueous environments, making these films able to be applied in architectural pieces as sculptures or other decorative parts, maintaining their properties with good aesthetical properties., The authors acknowledge to MIT Portugal-2017 program by thefinancial support through FCT/MCTES for this exploratory researchproject with the reference MIT-EXPL/ISF/0006/2007 and PhysicsCenter of University of Minho and University of Porto (CFUM-UP) by itssupport though the strategical project (UID/FIS/04650/2019). Thisstudy was supported by the Portuguese Foundation for Science andTechnology (FCT) under the scope of the strategic funding of UID/FIS/04650/2019 and UID/BIO/04469/2019 unit and BioTecNorte opera-tion (NORTE-01-0145-FEDER-000004) funded by the EuropeanRegional Development Fund under the scope of Norte2020—ProgramaOperacional Regional do Norte and, in the framework of the ATRITO-0(co-financed via FEDER (PT2020) POCI-01-0145-FEDER-030446 andFCT (PIDDAC)) and the On-SURF (co-financedvia FEDER (PT2020)POCI-01-0247-FEDER-024521) projects., info:eu-repo/semantics/publishedVersion

Surface modifications have been deeply investigated to improve their properties (nano-morphology/topography and chemistry), mainly to enhance surface bioactivity and consequently to overcome the current dental implants failures. For this purpose, the main goal of this work is to mimic the bone morphology as well as its chemical composition by the incorporation of calcium (Ca), phosphorus (P) and magnesium (Mg) on a tantalum (Ta) surface. Two approaches were used: reverse polarization (RP) and/or anodization, under different applied potential and acid-free electrolytes. It was observed that RP followed by anodization promoted the incorporation of cations (Ca2+, Mg2+ and Na+) in a competitive way. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses showed formation of amorphous calcium phosphate compounds. Moreover, a surface enriched with Ca, P and Mg achieved a Ca/P ratio of 1.4 similar to the stoichiometric hydroxyapatite (1.67). The surfaces subsequently became rougher and hydrophilic with their biofunctionalization. All these surface features are good pointers towards a better implant osseointegration.

This work aims to study the influence of the thickness on the wettability behaviour and on the tribological performance of thin WS2–C coatings doped with fluorine (F) deposited by magnetron sputtering. The morphology of the coatings did not change with the thickness decrease, revealing an increase on both the compactness and on the smoothening of the coating surface with F increase. Such an evolution led to more hydrophilic and less oleophilic surface behaviour. XRD results showed that the coatings start growing with an alignment of the (002) planes parallel to the substrate, which changed for randomly oriented crystals with the thickness increase. F insertion induced a decrease in the crystallinity, more evident in the case of thinner coatings. This result was corroborated by Raman analysis which showed a broadening of the main peaks assigned to WS2. Tribological tests carried out at room temperature without lubrication showed lower friction coefficient for F-doped coatings, especially for the thinner one (in the overall test, average 0.03). Regarding the lubricated tests performed with pure PAO (polyalphaoleophin) oil, both thin coatings presented similar friction coefficients (∼0.07) in the steady-state regime. The tribolayer based on oriented W–S layers formed on the wear track for the F-doped coating can justify the very low friction achieved when testing in non-lubricated conditions.

In this work Ta1 − xOx coatings were deposited by DC magnetron sputtering in an Ar + O2 atmosphere. The influence of the oxygen partial pressure on the morphology (SEM), structure (XRD), chemical bonding (XPS), thermal oxidation and optical response (FTIR and spectroscopic ellipsometry) of Ta-based films was study. Cross-section morphology revealed that the increase of oxygen content in the coatings change the columnar morphology to featureless. Likewise, structural results showed that the small increase of oxygen amount leads to a change from Ta stable phase (α-Ta: bcc) to a mixture of phases achieving oxide phases with large amounts of oxygen. Whereas at room temperature the oxide coatings mainly revealed an amorphous character, at 700 °C the coating reached the crystallization Ta2O5 orthorhombic phase, which is promoted by the temperature. Further, although not observed in XRD, for the coatings deposited close to the reactive mode threshold IR showed absorption bands corresponding to amorphous phase containing some crystals embedded on it, while for the coatings deposited in the poisoned regime the IR suggests a marked amorphous nature. Refractive index varied between 2.09 and 2.27 at 0.65 μm, within the range reported for Ta2O5 thin films. The changes in refractive index are correlated with the different crystallinity of the coatings, which is corroborated with the IR results., This research is sponsored by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/ FIS/04650/2013 and with a PhD fellowship SFRH/BD/98199/2013. The authors also thank the financial support by IAPMEI funds through QREN – Implantes dentários inteligentes – SMARTDENT, Projeto Vale Inovação n.° 2012/24005, the project “Efeito sobre a saúde humana do tratamento de couros para a indústria do calçado com nanomateriais de Ag-TiO2 - ERA-SIINN/0004/2013” financed by OE of FCT, the PAULIF program “Programa Ações Universitárias Integradas Luso-Francesas – PAUILF – 2014” with the project “Development of bioactive surfaces for bone ingrowth on dental implant”, action integrated number TC 08/14 and MCTES – SPRH/BSAB/128423/2017 project., info:eu-repo/semantics/publishedVersion

In this report Zr C N Ag coatings produced by dual magnetron sputtering are characterized by X-ray photoelectron spectroscopy (XPS) and complemented byX-ray diffraction, scanning electron microscopy, electron-probe microanalysis and Raman spectroscopy, in order to determine the chemical bonds and phases formed during the production process. The results demonstrate the possibility of producing coatings with different silver content (0–16 at.%), in which zirconium carbonitrides (70–95 at.%), amorphous carbon nitride phases (0–16 at.%) and residual zirconium oxide phases (∼5 at.%) coexists with the metallic silver. The profile analysis evidenced a highly oxidized surface due to the affinity of Zr to form ZrO2, and silver segregation to the surface. The composition after Ar+ bombardment revealed the contribution of silver clusters and metallic silver, together with the mentioned phases that vary in content depending on the deposition parameters utilized. STEM images revealed silver nanoparticles distributed in the Zr C N matrix with sizes around 5–20 nm, as well as silver surface agglomeration with sizes, This research is partially sponsored by FEDER funds through the program COMPETE – Programa Operacional Factores de Competitividade and by Portuguese national funds through FCT – Fundac¸ ão 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/UI607/2013”, PEST-C/EME/UI0285/2013 and SFRH/BD/80947/2011. Authors thank Juan Carlos Sanchez for the Raman spectroscopy measurements at the CSIC-US., info:eu-repo/semantics/publishedVersion

This paper reports on the control of wettability behaviour of a 6000 series aluminum (Al) alloy surface (Al6016-T4), which is widely used in the automotive and aerospace industries. In order to induce the surface micro-nanostructuring of the surface, a combination of prior mechanical polishing steps followed by anodization process with different conditions was used. The surface polishing with sandpaper grit size 1000 promoted aligned grooves on the surface leading to static water contact angle (WCA) of 91◦ and oil (-bromonaphthalene) contact angle (OCA) of 32◦, indicating a slightly hydrophobic and oleophilic character. H2SO4 and H3PO4 acid electrolytes were used to grow aluminum oxide layers (Al2O3) by anodization, working at 15V/18◦ C and 100V/0 ◦C, respectively, in one or two-steps configuration. Overall, the anodization results showed that the structured Al surfaces were hydrophilic and oleophilic-like with both WCA and OCA below 90◦. The one-step configuration led to a dimple-shaped Al alloy surface with small diameter of around 31 nm, in case of H2SO4, and with larger diameters of around 223 nm in case of H3PO4. The larger dimples achieved with H3PO4 electrolyte allowed to reach a slight hydrophobic surface. The thicker porous Al oxide layers, produced by anodization in two-step configuration, revealed that the liquids can penetrate easily inside the non-ordered porous structures and, thus, the surface wettability tended to superhydrophilic and superoleophilic character (CA< 10◦). These results indicate that the capillary-pressure balance model, described for wettability mechanisms of porous structures, was broken. Moreover, thicker oxide layers with narrow pores of about 29 nm diameter allowed to achieve WCA< OCA. This inversion in favour of the hydrophilic-oleophobic surface behaviour is of great interest either for lubrication of mechanical components or in water-oil separation process., This research work is supported by FEDER funds through the program COMPETE – Programa Operacional Factores de Competitividade – by national funds through FCT – Fundac¸ ão para a Ciência e a Tecnologia in the framework of the Strategic Funding UID/FIS/04650/2013, UID/EMS/00285/2013 and with a PhD fellowship PD/BD/112079/2015. This work was also sponsored by IAPMEI funds through QREN 38587 2014/2015-CleanTool project, ERA-SIINN/0004/2013-NanoSafeLeather project and PTDC/CTMNAN/4242/2014-ClusterStent project., info:eu-repo/semantics/publishedVersion

In this work, oxidation of carbon supported Zn nanostructures was studied to elucidate their utilization as oxygen scavenging materials activated by the relative humidity in the environment. Moisture-activated nano-scavengers were produced on carbon substrates using magnetron sputtering attaining nano-islands (nanoparticles), randomly distributed on the carbon surface, with arbitrary crystallographic orientations. They possess a Zn–ZnO core–shell structure, caused by surface passivation, which provides them with a self-assembled protective layer that prevents complete oxidation of nanoparticles prior to utilization. The oxidation rate is independent of the nanoparticle size and orientation, for particles between 5 and 18 nm. The oxidation kinetics are not in complete agreement with the Cabrera and Mott theory. When exposed to a high relative humidity environment, an acceleration in the oxidation process is observed, dissolving the Zn nanoparticles and forming a layer on the carbon, which facilitates the consumption of the Zn to form ZnO. These results support the idea of its potential use in applications where high RH environments are required, such as food packaging., This research is sponsored by FEDER funds through the program COMPETE – Programa Operacional Factores de Competitividade and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013, and UID/EMS/00285/ 2013 and in the framework of the ERA-SIINN/0004/2013 project., info:eu-repo/semantics/publishedVersion

Ag and AgOx thin films were deposited by pulsed DC magnetron sputtering, for medical devices, in order to provide antibacterial properties. During the deposition process, oxygen flow, and, consequently, oxygen fraction, was varied (0â15 sccm) to understand the influence of oxygen species in the physical, chemical and structural properties of thin films. Coatings morphology was observed by scanning electron microscopy (SEM) and their nanostructure and composition were assessed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS), respectively. XRD and XPS analyses revealed that Ag thin films are composed by metallic Ag, which crystallizes in fcc-Ag phase; whereas AgOx showed a mixture of Ag2O and AgO phases for low oxygen fraction that became single AgO with the increase of oxygen fraction in the discharge. Surface wettability and surface tension of the coatings were also determined showing hydrophobic character. Halo inhibition zone tests were performed against Staphylococcus epidermidis, in order to evaluate the antibacterial behavior of coatings, and silver ion release was measured. Only AgOx presented antibacterial behavior, showing that the presence of silver oxide are the main reasons for the antibacterial effect, probably due to the increased production of ROS (Reactive Oxygen Species),making these coatings promising for medical applications., The authors acknowledgments the financial support of FCTFundação para a Ciência e Tecnologia through grant SFRH/BD/90321/2012. Also thank support by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013, and projects ERA-SIINN/0004/2013 through the “Fundo Europeu de Desenvolvimento Regional” (FEDER).

TiSiN coatings alloyed with increasing silver content were deposited for designing a self-lubricant coating with controlled lubricant element diffusion. Here, we report the influence of the Ag content on the oxidation behaviour of TiSiN(Ag) films deposited by HiPIMS (High Power Impulse Magnetron Sputtering) working in DOMS (Deep Oscillation Magnetron Sputtering) mode. In-situ high-temperature oxidation X-ray diffractograms allowed to observe the first signs of oxidation occurring at about ~ 850 °C with the appearance of the rutile TiO2 peaks. Observation of even distribution of silver was still possible on the un-oxidized part of the films, suggesting that the films offer an efficient barrier to the Ag diffusion. Dynamic-mode thermogravimetry analysis showed that silver addition does not change the onset point of oxidation of the coatings. However, the oxidation rate deteriorated with the presence of Ag. An unusual mass loss could be observed for the coatings with 6 and 10 at.% of Ag, as a result of silver evaporation/sublimation process. Results from isothermal thermogravimetry performed at 900 °C show two distinct regimes and corroborate the detrimental effect of the Ag on the oxidation resistance of the coatings. Nonetheless, in the un-oxidized part of the films, the silver continued to be homogeneously distributed confirming again the efficient barrier against Ag diffusion.

In this study, Ta1-xOx coatings were deposited by reactive magnetron sputtering aiming at the enhancement of the electrochemical stability stainless steel 316L. The coatings were produced using variable oxygen content in order to determine its influence on the films morphological features and corrosion resistance. Structural and morphological characteristics were correlated with the corrosion behavior in artificial saliva. Potentiodynamic and electrochemical impedance spectroscopy tests were complemented with X-ray photoelectron spectroscopy to determine the electrochemical behavior of the coatings. The results reveal a more protective behavior of the coatings as the oxygen amount increases in the films, as well as pitting inhibition in the coated stainless steel, independently of the film composition. A synergetic effect between Ta2O5 and phosphate-based passive layers is suggested as the protective mechanisms of the coatings; while the more active electrochemical behavior of low oxygen content films is evidenced as a consequence of the metallic tantalum on the surface with a more open morphology and larger density of defects on the surface., This research is sponsored by FEDER funds through the program COMPETE – Programa Operacional Factores de Competitividade – by national funds through FCT – Fundação para a Ciência e a Tecnologia , in the framework of the Strategic Projects PEST-C/FIS/UI607/2013, and PEst-C/EME/UI0285/2013, and with a PhD fellowship SFRH/BD/98199/2013. The authors thank the financial support by IAPMEI funds through QREN – Implantes dentários inteligentes – SMARTDENT, Projeto Vale Inovação n. 2012/24005 and by MCTI/CNPQ N 16/2012 TECNOLOGIAS INOVADORAS NA PRODUÇÃO, PROTOTIPAGEM E/OU AUMENTO DE ESCALA EM NANOTECNOLO- GIA – Desenvolvimento de Titânio e Liga de Titânio Nano-estruturados com Tratamentos de Superfície para Aplicação em Implantes Ósseos.

The use of dental implants is sometimes accompanied by failure due to periimplantitis disease and subsequently poor esthetics when soft-hard tissue margin recedes. As a consequence, further research is needed for developing new bioactive surfaces able to enhance the osseous growth. Tantalum (Ta) is a promising material for dental implants since, comparing with titanium (Ti), it is bioactive and has an interesting chemistry which promotes the osseointegration. Another promising approach for implantology is the development of implants with oxidized surfaces since bone progenitor cells interact with the oxide layer forming a diffusion zone due to its ability to bind with calcium which promotes a stronger bond. In the present report Ta-based coatings were deposited by reactive DC magnetron sputtering onto Ti CP substrates in an Ar+O2 atmosphere. In order to assess the osteoconductive response of the studied materials, contact angle and in vitro tests of the samples immersed in Simulated Body Fluid (SBF) were performed. Structural results showed that oxide phases where achieved with larger amounts of oxygen (70 at.% O). More compact and smooth coatings were deposited by increasing the oxygen content. The as-deposited Ta coating presented the most hydrophobic character (100°); with increasing oxygen amount contact angles progressively diminished, down to the lowest measured value, 63°. The higher wettability is also accompanied by an increase on the surface energy. Bioactivity tests demonstrated that highest O-content coating, in good agreement with wettability and surface energy values, showed an increased affinity for apatite adhesion, with higher Ca/P ratio formation, when compared to the bare Ti substrates., This research is sponsored by FEDER funds through the program COMPETE – Programa Operacional Factores de Competitividade – by national funds through FCT—Fundação para a Ciência e a Tecnologia—, in the framework of the Strategic Projects PEST-C/FIS/UI0607/2013, and PEst-C/EME/UI0285/2013, and with a PhD fellowship SFRH/BD/98199/2013 and by IAPMEI funds through QREN — Implantes dentários inteligentes — SMARTDENT, Projeto Vale Inovação n.° 2012/24005.

Silver diffusion within nanocomposite films and/or toward the film surface is often observed during annealing of the silver-based nanocomposite films. In order to control and/or minimize this process, it is crucial to characterize the aggregated silver nanoparticles on the films surface. In this paper grazing incidence X-ray diffraction (GIXRD) with both sub-critical and supra-critical angles of incidence is used to characterize the Ag nanoparticles distribution, shape and structure both inside the matrix and on the nanocomposite film surface. The nanocomposite carbon coating containing Ag nanoparticles (a-C:Ag) was deposited by dc magnetron sputtering. The coatings were analyzed by GIXRD using fixed incident angles both below and above the critical angle for total reflection. By using sub-critical angles it was possible to eliminate diffraction from the bulk material allowing to estimate the size distribution of the nanoparticles sitting on the surface. The results obtained by GIXRD analysis were checked through comparison with the observations made by both TEM and SEM analysis. The proposed methodology can be used to characterized nanoparticles deposition on a surface and/or island formation during film growth as long an adequate substrate with high critical angle for total reflection is used., We gratefully acknowledge the financial support provided by the FCT—Fundação para a Ciência e Tecnologia and FSE for the grant SFRH/BD/82472/2011. This research is sponsored by the FEDER funds through the program COMPETE—Programa Operacional Factores de Competitividade and by the national funds through FCT—Fundação para a Ciência e Tecnologia in the framework of the Strategic Projects PEST C/EME/UIO0285/2011.

The main aim of this work was to study the feasibility of new coatings for medical devices. Ti-Si-C-O-N films were deposited by DC unbalanced reactive magnetron sputtering, using different oxygen and nitrogen partial pressure ratios (pO2/pN2). Surface properties were also analysed. Staphylococcus epidermidis was used to study biofilm formation and cytotoxicity was determined using fibroblasts. Surface morphology changed with the increase of pO2/pN2. Samples of high hydrophobicity displayed opposite behaviour in terms of biofilm formation, presenting the highest and lowest biomass. Moreover, the sample with the highest Ti content was the one, with the lowest biofilm amount, raising the possibility of a correlation between Ti and biofilm formation capability. In fact, this sample also displayed the highest degree of cytotoxicity (near 35%). This work shows the feasibility of the proposed coatings and highlights the importance of joining together both biological properties (biofilm formation and cytotoxicity) with the surface characterization.

Forma parte de número especial: Proceedings of the 35th International Conference on Metallurgical Coatings and Thin Films Ti–Si–C–ON films were deposited by DC reactive magnetron sputtering using different partial pressure ratio of oxygen (pO2) and nitrogen (pN2). Compositional analysis revealed the existence of three different growth zones for the films; (I) N/Ti = 2.1 (high atomic ratio) and low oxygen content; (II) 0.76 < N/Ti < 2.1 (intermediate atomic ratio) and (III) N/Ti ≤ 0.12 (low ratio) and high oxygen content. For high N/Ti atomic ratio (N/Ti = 2.1) the XRD pattern exhibits reflections that correspond to a mixture of two different phases: a metallic-like Ti and a fcc NaCl type structure. Its electrical resistivity presents a metallic character and, consequently, has high infrared reflectivity. For the intermediate N/Ti ratio (0.76 < N/Ti < 2.1), the films crystallize in a B1-NaCl crystal structure typical for TiC0.2N0.8. Their FTIR spectra present C–N modes, besides the TiN ones, that indicate a progressive substitution of nitrogen by carbon atoms with increasing oxygen content (and lowering N/Ti ratio). For the highest oxygen content (and lower N/Ti ratio) the presence of the Ti–O–Ti stretching mode shows the formation of highly resistive Ti–O compounds consistent with the semiconductor character of this film. Biofilm formation as well as material cytotoxicity seemed to be related with the presence of the Ti.