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Dispersions of oleate-capped ZnO nanoparticles (NPs) in binary n-octane/1,7-octadiene solvent mixtures are injected, in aerosol form, in a dielectric barrier discharge to deposit hydrocarbon polymer/ZnO nanoparticles nanocomposite (NC) thin films at atmospheric pressure and room temperature. The chemical composition of the coatings, and in turn their morphology and wettability, can be tuned by simply changing the composition of the starting dispersion. Specifically, the increase of the NPs concentration in the dispersion (0.5–5 wt%) results in a continuous increase of both the ZnO content and deposition rate of the coatings. Moreover, when the concentration of 1,7-octadiene in the solvent mixture is very low (0.5–2 vol%), the incorporation of NPs is further promoted, while at concentrations >2 vol% the growth of the organic component starts to be favored. Overall, results reveal a considerable increase of the root-mean-square (RMS) roughness of the coatings with the ZnO loading. In addition, once the threshold ZnO loading and RMS roughness of 60 wt% and 350 nm are reached, respectively, the coatings are superhydrophobic and exhibit very low water contact angle hysteresis, due to the coexistence of the low surface energy conferred by the hydrocarbon polymer and the hierarchical multiscale surface texture induced by NPs incorporation.

Iron oxide thin films for photoelectrochemical (PEC) water splitting were deposited by radiofrequency sputtering of an iron target in argon/oxygen plasma mixtures, followed by thermal annealing. The chemical composition and structure of deposited film can be tuned by controlling the gas feed composition and the annealing temperature. The thermal treatment extensively improves the PEC water splitting performances of the films deposited at the lowest O2 percentages (0–1%), allowing to obtain photocurrent densities up to 1.20 mA/cm2 at 1.23 VRHE. Increasing the oxygen percentage in the plasma feed allows the direct growth of photoactive films; the best result is found for the hematite film produced at 50% O2, characterized by a photocurrent density of 0.21 at 1.23 VRHE.

In this work, for the first time, snail slime from garden snails "Helix Aspersa Müller", has been used to induce the formation of eco-friendly gold nanoparticles (AuNPs-SS) suitable for biomedical applications. An AuNPs-SS comprehensive investigation was performed and AuNPs with an average particle size of 14 ± 6 nm were observed, stabilized by a slime snail-based organic layer. Indeed, as recognized in high-resolution MALDI-MS analyses, and corroborated by FESEM, UV-Vis, ATR-FTIR, and XPS results, it was possible to assess the main presence of peptides and amino acids as the main components of the slime, that, combined with the AuNPs confers on them interesting properties. More specifically, we tested, in vitro, the AuNPs-SS safety in human keratinocytes and their potential effect on wound healing as well as their anti-inflammatory properties in murine macrophages. Moreover, the AuNPs-SS treatment resulted in a significant increase of the urokinase-type plasminogen activator receptor (uPAR), essential for keratinocyte adhesion, spreading, and migration, together with the reduction of LPS-induced IL1-? and IL-6 cytokine levels, and completely abrogated the synthesis of inducible nitric oxide synthase (iNOS). This journal is

Atmospheric pressure non-equilibrium (cold) plasma jet technology received enormous attention in surface processing of materials in the last two decades, and still continues nowadays to attract growing interest. In addition to the advantages of the atmospheric pressure operation such as the potential cost reduction of apparatuses as well as their easier handling and maintenance, due to the distinctive remote operation, plasma jets give the unique possibility of placing the substrate outside the source boundaries. Consequently, the processing of complex three-dimensional objects and the integration into existing production lines are expected to be much easier. However, while appealing, plasma jet technology has the drawback that great efforts are required for process optimization, since many factors can affect, for instance, the physical and chemical proprieties of the so-called “plasma plume” emanating from the devices and propagating in open space towards the substrate to be treated. The aim of this paper is to provide a critical literature review on the utilization of atmospheric pressure non-equilibrium plasma jets in surface processing of materials. Starting from the description and classification of the multitude of devices used in this applicative field so far, the attention will be drawn on some very important aspects to be taken into account in process optimization. The discussion will be focused on basic concepts and peculiarities closely related to the remote operation of the plasma sources, which include the characteristics and dynamics of the plasma plume interacting with the substrate and the surrounding atmosphere. Since the plasma jet approach allows the surface modification of small localized regions of the sample, the strategies implemented to enlarge the treated area will be also addressed. Finally, a brief overview will be given of the available applications and recent developments in the field of etching, thin film deposition and treatment.

Made available in DSpace on 2020-12-12T02:30:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-11-25 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Carbon steel is the most commonly used material for sheets, plates, bars and tubes in mechanical metallurgy and construction industry. However, the susceptibility of carbon steel to oxidation under real conditions of use turns preventive and corrective repairs mandatory. Many published studies show that plasma deposited silica and organosilicon layers can be used as corrosion barriers, being the first one more efficient due to its higher chemical density and inertness. However, the performance of SiOx layers may be affected by mechanical stress, and especially by defects generated in the deposition process or by the substrate finishing. To associate the good corrosion resistance of the silicon oxide films to the flexibility of organosilicon ones, some authors created multilayered systems, intercalating organosilicon and silica layers. However, the adhesion between the organosilicon and inorganic layers in these multilayered systems is still a problem, since there is a well-defined interface between them and both layers are just slightly interconnected. In this sense, the purpose of the present work is to create, from plasma polymerization of hexamethyldisiloxane, an organosilicon-silica gradual system and to investigate its barrier and mechanical properties. SiOx/SiOxCyHz gradual films were deposited by low pressure radiofrequency (13.56 MHz) plasmas using HMDSO, Ar and O2 mixtures. The change of an organosilicon to inorganic coating or vice versa was made only by adjusting the plasma conditions without interrupting the process. The influence of the carbon steel native oxide pre-deposition treatment in O2 plasma was also evaluated. Electrochemical Impedance Spectroscopy, EIS was used to evaluate the corrosion resistance provided by the gradual system to the carbon steel. Infrared spectroscopy, FTIR, was applied to analyze the chemical composition and molecular structure. The thickness of the films was measured by profilometry. Surface wettability was assessed from contact angle measurements using an automated goniometer. The morphology of the samples was inspected by secondary electrons micrographs acquired using a scanning electron microscope while the mechanical properties of the systems were examined by nanoindentation. The oxidation treatment performed on the substrate surface prior to deposition improve the corrosion resistance of the samples. The total corrosion resistance increases six orders of magnitude when carbon steel was coated with a quaternary gradual coating of only 2 μm. Laboratory of Technological Plasmas (LaPTec) São Paulo State University (UNESP) Science and Technology Institute of Sorocaba (ICTS), Av. Três de Março, 511 Department of Chemistry University of Bari Aldo Moro, Via Orabona 4 Laboratory of Technological Plasmas (LaPTec) São Paulo State University (UNESP) Science and Technology Institute of Sorocaba (ICTS), Av. Três de Março, 511 FAPESP: 2012/14708-2 FAPESP: 2013/05012-7 FAPESP: 2014/24707-9

Polymeric films containing hydrophilic and hydrophobic functionalities are of interest for several applications, from biomaterials to fuel cells. In this study, we report on the plasma copolymerization of hexafluoropropene - acrylic acid mixtures. By finely tuning the monomers’ ratio and the plasma power, it is possible to adjust the relative amount of the hydrophilic and hydrophobic functionalities in the deposited films. Correspondingly, the wetting behavior can be tuned from fully hydrophilic to hydrophobic. Finally, depending on the process parameters, film proton conductivities in the range 20–70 mS cm−1 are obtained.

A novel method has been developed for the deposition of PEG containing coatings with cell repulsive properties. PEG is atomized from a water solution directly in a dielectric barrier discharge where, due to the presence of a film precursor, ethylene, a composite coating is deposited. Morphological characterization evidenced the globular appearance of the coatings due to the presence in the feed of solution droplets. The chemical characterization, and in particular the MALDI-TOF analysis confirmed the presence of PEG-like regions, in an amount decreasing with increasing the ethylene content in the film. Finally, cell adhesion was considerably reduced for the PEG-rich deposited coatings.

The atmospheric pressure non-equilibrium plasma treatment of open-cell polyurethane foams is carried out using dielectric barrier discharges fed with helium and oxygen mixtures. During plasma processes, the discharge is ignited both outside the foam and within its porous structure to achieve the three-dimensional surface modification of the entire substrate. X-ray photoelectron spectroscopy results reveal the uniform functionalization of both the exterior and interior surfaces of the porous material with oxygen-containing groups. In addition, nuclear magnetic resonance spectroscopy analyses confirm that surface chemical modification occurs with preservation of the foam polymeric skeleton. Scanning electron microscopy observations and water contact angle measurements show that the plasma-treated foams exhibit increased surface roughness and wettability, respectively. It is also observed that aging of the plasma-treated foams is more pronounced in water than in air, due to the inevitable dissolution of oxidized polymer fragments formed during plasma exposure. Finally, it is found that a simple post-processing step improves the capability of the plasma-treated foams to remove heavy metal ions from water, as demonstrated through Cd2+ adsorption experiments.

Thin films are deposited on open-cell polyurethane (PU) foams using an atmospheric pressure dielectric barrier discharge (DBD) fed with helium and hexafluoropropene (C3F6). During deposition processes, a foam substrate is sandwiched between the dielectric-covered electrodes of a parallel plate DBD reactor, so that the discharge can ignite also inside its three-dimensional (3D) interconnected porous structure. This affords the deposition of a fluorocarbon coating on both the exterior and interior of the foam. Scanning electron microscopy (SEM) observations allow estimating the thickness of the coating deposited on the foam struts, while X-ray photoelectron spectroscopy (XPS) analyses show moderate changes in surface chemical composition moving from the outer to the inner surfaces of the plasma-treated foams under all explored experimental conditions.

During the last years, the employment of light polymeric materials, to replace those commonly used in the automotive industry, has been investigated by many equipment manufacturers. Polymeric glazing, e.g. polycarbonate, are desirable because of their ability to reduce weight and fuel consumption, while providing good optical properties and impact resistance. In this paper, we report a two steps low pressure plasma treatment composed by an etching, optimized for the nano-texturing of polycarbonate to improve its anti-reflective property by simulating the so-called “Moth eye” effect, and by a plasma enhanced-chemical vapour deposition process to enhance the scratch resistance. Reflectance/transmittance measurements showed that this approach is able to increase the anti-reflective property of the polycarbonate without drastically damaging its transmittance, while scratching test by “car wash” simulator demonstrated the increase of scrape resistance. The haze test confirmed the transparency of the plasma treated polymer also after washing.

A facile atmospheric pressure cold plasma process is presented to deposit a novel organic-inorganic hydrocarbon polymer/ZnO nanoparticles nanocomposite coating. Specifically, this method involves the utilization of an atmospheric pressure dielectric barrier discharge (DBD) fed with helium and the aerosol of a dispersion of oleate-capped ZnO nanoparticles (NPs) in n-octane. As assessed by X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, the deposited nanocomposite coating combines the chemical features of both the oleate-capped ZnO NPs and the polyethylene-like organic component originated from the plasma polymerization of n-octane. Additionally, scanning electron microscopy (SEM) and transmission scanning electron microscopy (TSEM) confirm the synthesis of hierarchical micro/nanostructured coatings containing quasi-spherical NPs agglomerates. The polyethylene-like polymer covers the NPs agglomerates to different extents and contributes to their immobilization in the three-dimensional network of the coating. The increase of both the deposition time (1-10 min) and the NPs concentration in the dispersion (0.5-5 wt %) has a significant effect on the chemical and morphological structure of the thin films and, in fact, results in the increase the ZnO NPs content, which ultimately leads to superhydrophobic surfaces (advancing and receding water contact angles higher than 160°) with low hysteresis due to the hierarchical multiscale roughness of the coating.

Thin films containing carboxylic acid groups are deposited on open-cell polyurethane (PU) foams by using an atmospheric pressure non-equilibrium plasma jet, in dielectric barrier discharge configuration, fed with helium, acrylic acid and ethylene. The arrangement of the plasma jet, the sample holder, and the substrate is carefully optimized to enable the penetration of the plasma ejected from the remote source throughout the three-dimensional (3D) porous structure of the foam, and, therefore, to achieve the uniform coverage of the entire substrate. X-ray photoelectron spectroscopy analyses and scanning electron microscopy observations confirm that both the outer and the inner surfaces of the foam can be functionalized with the plasma-deposited coating, showing moderate changes in surface chemical composition and coating thickness moving from the exterior to the interior of the plasma-treated samples. The ability of the foams to adsorb heavy metals from water is tested through evaluation of cadmium ions (Cd2+) removal. The foams adsorption capacity can increase more than 10 times after plasma deposition and remains unchanged over 8 adsorption-release cycles.

Low pressure plasma, generated in a radio frequency reactor under rotation, was utilized to modify the ability of granular substrates to adsorb volatile acid compounds. Carbon black granules were treated with NH3 or allylamine containing feeds, while sepiolite granules were processed only in allylamine fed discharges. The chemical modifications induced by plasma treatments were evaluated by means of X-ray photoelectron spectroscopy studies and water contact angle measurements, while scanning electron microscope and Brunauer, Emmet, Teller analyses were performed to study the surface morphological changes caused by plasma processes. The ability of the treated materials to adsorb acids, in gas or vapour phase, was estimated with hydrochloric, acetic and propanoic acid, employing a home-made test system. The results show that the optimized plasma treatments are able to improve the adsorption ability of carbon black and sepiolite granules for the three acids investigated. re la tiv e ad so rb ed e qu iv al en ts % /se pi ol ite g HCl CH3CO2H CH3CH2CO2H

This work describes the plasma-enhanced chemical vapor deposition of thin films at atmospheric pressure using dielectric barrier discharges fed with argon, oxygen and different methyldisiloxanes, i.e., hexamethyldisiloxane, pentamethyldisiloxane, and 1,1,3,3-tetramethyldisiloxane. The influence of the methyldisiloxane chemical structure and of the oxygen/ methyldisiloxane feed ratio is investigated in order to provide insights into the organosilicon plasma chemistry at atmospheric pressure. As expected the FT-IR and XPS analyses show that the carbon content of the coatings depends on the number of methyl groups in the precursor molecule; in the case of coatings obtained with PMDSO and TMDSO carbon removal seems to be further enhanced by the presence of Si H bonds. Gaschromatography-mass spectrometry analyses of the exhaust gas allow to assess the precursor depletion and to perform the quali-quantitative determinationof by-products (e.g., silanes, siloxanes, silanols) formed by plasma activation. The results are exploited to rise hypotheses on the contribution of the different reaction pathways on the deposition mechanism.

This study deals with the investigation by means of gas chromatography-mass spectrometry (GC-MS) of the exhaust gas of an rf low pressure (LP) glow discharge and of an atmospheric pressure (AP) FDBD fed with hexamethyldisiloxane (HMDSO), O2, and Ar. The influence of feed composition on monomer depletion and on the qualitative‐quantitative distribution of stable by-products formed by recombination of plasma intermediates is investigated. Without O2 addition to the feed almost comparable values of HMDSO depletion are observed both at low and AP. Oxygen addition does not influence the monomer depletion at LP while it induces a slight decrease of the depletion at AP. Whatever the working pressure, O2 controls the overall chemistry of the plasma, since it influences the concentration of by-products (e.g., silanes, silanols, linear, and cyclic methylsiloxanes). At AP evidences of the importance of methyl abstraction from HMDSO molecule have been obtained, whileatLPtheprevalence ofSi‐Obondrupture, of fragmentation, and oligomerization reactions is observed. The comparison of results from the GCMS investigation of the exhaust gas with FT-IR spectra of the deposited coatings allows to enhance hypotheses on the formation of silanols in the gas phase and in the deposit.

Surface engineering has been explored using plasma enhanced chemical vapur deposition (PECVD) of SiO2-like coatings on different metallic substrates in order to improve their resistance to corrosion. Specifically, the coatings have been deposited onto silver-based alloys which are prone to unaesthetic tarnishing, by means of PECVD in radio frequency (RF) plasma fed with tetraetoxysilane/oxygen/argon mixture. Microchemical and microstructural characterization of the coatings has been carried out by means of X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The protective effectiveness against tarnishing of SiO2-like layers has been evaluated by immersion tests in 0.1M Na2S aerated solution at room temperature. It has been found that SiO2-like coatings deposited by increasing the oxygen-to-monomer ratio in the feeding-gas mixture and the input power density possess excellent barrier effects, and the coating adhesion increases if the deposition process is performed after a hydrogen plasma treatment. The protective effectiveness of PECVD coatings may be related to their barrier effect against the diffusion of water and other gaseous aggressive agents present in the environment and coming into contact with the metal surface. Copyright (C) 2010 John Wiley & Sons, Ltd.

The thin film deposition in DBDs fed with Ar/HMDSO/O2 mixtures was studied by comparing the FT-IR spectra of the deposits with the GC-MS analyses of the exhaust gas. Under the experimental conditions investigated, oxygen addition does not enhance the activation of the monomer while it highly influences the chemical composition and structure of the deposited coating as well as the quali-quantitative distribution of by-products in the exhaust. Without oxygen addition a coating with high monomer structure retention is obtained and the exhaust contains several by-products such as silanes, silanols, and linear and cyclic siloxanes. The dimethylsiloxane unit seems to be the most important building block of oligomers. Oxygen addition to the feed is responsible for an intense reduction of the organic character of the coating as well as for a steep decrease, below the quantification limit, of the concentration of all by-products except silanols. Some evidences induce to claim that the silanol groups contained in the deposits are formed through heterogeneous (plasma-surface) reactions.

The deposition and etching of plasma-polymerized fluorocarbon thin films were studied in filamentary dielectric barrier discharges (FDBDs) fed with Ar–CF 4 –H 2 and Ar–CF 4 –O 2 mixtures, respectively. The etching/polymerization competition was investigated as a function of the feed composition. Hydrogen addition to CF 4 promotes thin films deposition, with a maximum deposition rate at 20% H 2 , and reduces the F/C ratio of the deposit, while the oxygen addition promotes the etching of the plasma-deposited film. It is demonstrated that fluorine atoms can perform the etching of the fluoropolymer also without ion bombardment. The correlation between the trend of the etch rate and the trend of the surface chemical composition of fluoropolymers etched in Ar–CF 4 –O 2 mixtures allows to enhance hypotheses on the reaction mechanism and on the role of the different active species involved in plasma–surface interactions.

In this paper a single step process for the synthesis of composite thin films made of platinum nanoclusters embedded in a porous hydrocarbon matrix is proposed. The process consists of a simultaneous plasma enhanced-chemical vapour deposition of ethylene and sputtering of a platinum target. Films were characterized by means of Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. Optical emission spectroscopy was used to investigate the plasma phaseand tofind correlations with the metal content of thefilm. The effect of radio frequency power, deposition time, and ethylene flow rate on the chemical composition and structure of the film is presented. Results show that the platinum content in the film can be controlled by tuning the power delivered to the plasma and the monomer flow rate, and that the metal aggregates in crystalline nanoclusters uniformly distributed in the material. Film morphology is characterized by columnar structures of variable diameter and orientation depending on the deposition conditions.

In this paper, we review different plasma processes developed in our laboratory to obtain nanostructured superhydrophobic polymer surfaces. All methods consist of a single step and lead to functional materials which combine a fluorinated chemistry with unique surface morphologies. The transition from sticky to slippery superhydrophobicity, crucial for several applications ranging from microfluidics to outdoor self-cleaning surfaces, is found by properly tuning process parameters. Methods are compared in terms of process time-scale and compatibility to different substrates.

The influence of air and water vapour on the deposition process of fluoropolymers in argon-hexafluoropropene (Ar-C3F6) filamentary dielectric barrier discharges was investigated by adding known concentrations of these contaminants to the feed gas. The obtained results show that Ar-C3F6 DBDs allow in depositing thin films with a XPS F/C ratio as high as 1.7. Under the experimental conditions investigated, contaminant addition slightly affects the F/C ratio of the coatings, and does not cause appreciable O- and N-uptake, but induces a decrease of the deposition rate. Preliminary results from the OES investigation of the gas phase and the GC-MS analysis of the gas effluent are also reported.

Silicon nitride-like films can be deposited by inductively coupled discharges fed with dimethylaminosilanes without addition of reactive gases. At high input power fairly inorganic films can be obtained. In the present work in situ diagnostics of plasma phase, i.e. Fourier transform infrared spectroscopy (FT-IRAS) and optical emission spectroscopy (OES), have been utilized to investigate the deposition mechanism of bis(dimethylamino)dimethylsilane (BDMADMS) fed discharges. Results indicate that the monomer undergoes a pronounced depletion even at low input power and that fragmentation increases with increasing this parameter. The main fragmentation steps seem to involve the cleavage of the Si-N bond and the conversion of the -NMe 2 group.

Thin films with a dielectric constant in the range of 1.9-4.5 have been deposited under different experimental conditions from allyltrimethylsilane (ATMS) and oxygen fed glow discharges. The thermal stability of the coatings is evaluated from thickness loss during the annealing process at 400 and 450 °C. Extremely low values of dielectric constant can be obtained at low input power and oxygen flow rate. However, control over the annealing temperature must be gained in order to avoid excessive film matrix collapse with subsequent deterioration of dielectric properties. For the lowest dielectric constant of 1.9, thickness shrinkage of 11% has been detected. Deposition temperature is also found to strongly affect film dielectric constant and chemical composition while input power modulation does not improve the dielectric properties of the films.

The deposition of fluorocarbon films from GDBDs fed with helium-hexafluoropropene (He-C(3)F(6)) and helium-octafluoropropane-hydrogen (He-C(3)F(8)-H(2)) mixtures was investigated. The effect of several parameters was evaluated in order to clarify both the GDBD existence domain and film characteristics. He-C(3)F(6) GDBDs allowed to obtain films with an F/C ratio of 1.5 and to achieve deposition rates up to 35 nm . min (-1). By changing the H(2) content in He-C(3)F(8)-H(2) fed GDBDs it was possible to vary the crosslinking degree, to tune the F/C ratio of the coatings and to change the deposition rate which was maximized for an H(2)/C(3)F(8) ratio close to 1. A spectroscopic investigation of the plasma phase is also presented.

Thin films of plasma-polymerized thiophene (PPTh) were deposited on cold-rolled steel substrates to improve adhesion to rubber compounds. PPTh films were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and atomic force microscopy. The ratio of carbon-to-sulfur found in PPTh films is 4:1, suggesting the monomer structure is generally intact, which was supported by FT-IR absorptions characteristic of polymerized thiophene rings. However, some fragmentation did occur to give acetylenic and aliphatic groups. Steel–rubber adhesion measurements, performed in accordance with the ASTM 429-B peel test, strongly depended on cleaning and pretreatment methods as well as film thickness. Best results were obtained on polished steel samples that were cleaned with acid, pretreated with a hydrogen/argon plasma, then coated with 50 A of PPTh film. These samples exhibited a peel force of 14.3 N/mm, which is comparable to that of polished brass control samples. Depth-profiling XPS analysis of the rubber–steel interface showed the existence of an iron sulfide layer which is likely responsible for the strong adhesion.

Plasma enhanced chemical vapor deposition (PECVD) from silicon-containing organic compounds, such as SiO, coatings, appears to be an attractive treatment technique for the surface modification of metals in order to increase their corrosion resistance. This study deals with the characterization of SiN x thin films, in comparison with SiO x coatings, deposited on steels and aluminum alloys in a capacitively coupled (CC) parallel-plate reactor and in an inductively coupled (IC) reactor. The nitride-like coatings have been deposited in plasma fed with bis(dimethylamino)dimethylsilane (BIS) and Ar on as-received substrates and after a plasma treatment performed in oxygen or hydrogen plasmas. SiO x coatings have been deposited starting from tetraethoxysilane (TEOS) in a mixture of Ar and O 2 . The substitution of oxygen by nitrogen can lead to higher tribological and mechanical properties, maintaining the insulating nature of the film. Surface and chemical characterization of the coatings have been carried out by means of X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared spectroscopy (FTIR). The protective effectiveness of PECVD coatings has been assessed by electrochemical impedance spectroscopy (EIS) and may be related to their barrier effect against the diffusion of water and gaseous aggressive agents from the environment toward the metal surface. Plasma pretreatments play an important role in determining the barrier properties of the film by reducing its defectiveness and enhancing its adhesion to the substrate.

The present work provides a detailed study of helium-ethylene dielectric barrier glow discharges. The effect of ethylene concentration, total gas flow rate, excitation frequency and applied voltage have been investigated in order to clarify both discharge operational mode, and coating composition. The discharge has been characterized by means of electrical measurements and optical emission spectroscopy, while the stable species contained in the gas effluent have been sampled and analyzed using gas chromatography with mass spectrometry detection to achieve indications on the reactive fragments generated inside the discharge. It has been observed that polyethylene-like coatings can be obtained for a wide range of electrical conditions, and the deposition rates have been found to range between 20 and 80 nm . min - 1 .

This paper deals with the deposition of silicon nitride-like films at low temperatures using radio frequency inductively coupled plasmas fed with bis(dimethylamino)- dimethylsilane (BDMADMS) and argon (Ar). The effect of input power and BDMADMS-to-Ar ratio on the chemical composition of the deposited films has been investigated by means of Fourier transform infrared absorption spectroscopy (FT-IRAS) and X-ray photoelectron spectroscopy (XPS) analysis. The results indicate that at high input power and low monomer-to-Ar ratio, low carbon and high nitrogen content films, stable and with a refractive index of 1.87, can be obtained. Under the same experimental conditions, high carbon content silicon carbonitride coatings have been deposited from hexamethyldisilazane and Ar fed discharges.

The use of magnesium and its alloys is limited by their high susceptibility to corrosion, that may be attributed to the presence of critical impurities and the high chemical reactivity of the magnesium itself. Such characteristic justifies the great interest of performing coating technologies for the protection of magnesium parts by using environmentally friendly and cheap processes, with particular relevance in the framework of the European context. While magnesium technologies are rapidly taking advantages of the research results obtained during the last years, some more efforts are necessary to evaluate the impacts of its production on the environment and on the use of existing energy resources. Following this main lines, the paper presents some results obtained in NANOMAG (“Development of Innovative Nanocomposite Coatings for Magnesium Casting Protection” – Growth Programme n. 40548), a research project sponsored by the European Commission in which magnesium and its coating processes are evaluated taking into account also their environmental performances with a life-cycle approach.

SiO(2)-like coatings have been deposited onto silver-based alloys by means of plasma-enhanced chemical vapor deposition (PECVD) fed with a tetraethoxysilane/ oxygen mixture in order to study their capability to protect the alloys from tarnishing. Chemical and morphological characterization of the coatings has been carried out by means of X-ray photoelectron spectroscopy (XPS), infrared absorption spectroscopy, and scanning electron microscopy, while tarnishing susceptibility has been evaluated by means of visual inspection after intermittent immersions in Na(2)S solution at room temperature. It has been found that coatings deposited from oxygen-rich mixtures at high input power are characterized by excellent protective properties.

Low pressure plasma technologies have been widely and successfully utilized for the production of a large variety of organic–inorganic nanocomposite (NC) thin films consisting of metal or metal oxide nanoparticles embedded in a polymer matrix. Recently, the deposition of this class of coatings has been also accomplished by atmospheric pressure cold plasmas using aerosol-assisted processes in which a dispersion containing preformed inorganic nanoparticles and the liquid precursor of the polymeric component is atomized and injected in aerosol form in the atmospheric plasma. This short review is aimed at presenting this approach which is expected to enlarge the range of structures and properties of organic–inorganic NC coatings deposited by cold plasma technologies.

The dry etching of cobalt silicide has been investigated to evaluate the most important process variables. It has been demonstrated that among the commonly used etchants, only chlorine atoms are suitable to react appreciably with CoSi 2 . Strong ion bombardments and high temperatures are necessary to obtain good etch rates and to initiate the process (a resistant surface contaminant layer must be removed). A detailed XPS investigation of CoSi 2 before and during the etching process is also reported.

The composition of films deposited in RF glow discharges fed with tetraethoxysilane and oxygen mixtures has been investigated by means of in situ x-ray photoelectron spectroscopy and infrared spectroscopy. These results, combined with mass spectrometric investigations of the gas phase, indicate that the overall deposition consists of several concurrent heterogeneous and homogeneous reactions

This paper deals with the deposition of thin films in capacitively coupled RF plasmas fed with bis(dimethylamino)dimethylsilane in mixture with argon. The effect of input power and of O 2 addition has been studied by means of a detailed FTIR investigation of the plasma phase and FTIR and XPS analyses of the deposits. High carbon content films with inorganic character are deposited in monomer-Ar discharges at high power. Input power rise results in higher monomer depletion but fragmentation appears not complete since SiMe, SiN, NMe absorptions are still evident. When the oxygen addition is high, a SiO 2 -like film is formed and the oxidation of the organic fraction appears directly correlated with CO 2 density in gas phase.

Thin films with low dielectric constant were deposited by PECVD from different organosilicon precursors. Film structure and properties were strongly affected by the precursor choice. Silane-based precursors resulted in films with permittivities as low as 2.3 with a limited thickness loss of 6% upon thermal annealing at 400 8C. Films deposited from siloxane monomers were characterized by increased thickness shrinkage of 11%. Thermal stability was correlated not only to the cross-linking degree but also to the presence of methylene bridges in the polymer backbone, which accounts for the better thermal stability of silane-based films. Substrate heating (150 8C) during deposition ensured the best balance between very low permittivities and good thermal stability.

Different processing issues dealing with plasma treatments for corrosion protection of metals are discussed. It is shown that plasma-deposited inorganic coatings cannot be enough to ensure optimum protection to metal degradation. In particular, designing a suitable plasma pre-treatment of the metal surface with the right feed gas can enhance the coating performance. The improvement due to pulsed mode deposition and hydrophobic layer coating are also discussed, leading both to one order magnitude increase in the charge transfer resistance with respect to continuous plasma deposited SiOx.

The mechanism of field-effect doping in the 123 high critical temperature superconductors (HTS) has been investigated by x-ray absorption spectroscopy in the presence of an electric field. We demonstrate that holes are created at the CuO chains of the charge reservoir and that field-effect doping of the CuO 2 planes occurs by charge transfer, from the chains to the planes, of a fraction of the overall induced holes. The electronic properties of the charge reservoir and of the dielectric-HTS interface determine the electric field doping of the CuO 2 planes.

He/CF 4 -fed GDBDs were used to fluorinate PP and PET. The effect of various process parameters on the polymers surface composition and morphology, as well as on their wettability was investigated inside the GDBD existence domain. An extensive surface fluorination of treated polymers due to the grafting of F atoms and CF x radicals was observed. The increase of CF 4 concentration in the feed, of treatment duration, and of excitation frequency resulted in an increase of the fluorination degree corresponding to F/C ratios as high as 1.18 and 1.22 for PP and PET, respectively. The emission spectra of GDBDs fed by helium in mixture with CF 4 , CHF 3 , C 2 F 6 and C 3 F 8 were compared.

Three dimethylaminosilanes, characterized by a different number of NMe2 groups bonded to silicon, have been compared as precursors in silicon nitride-like films plasma enhanced chemical vapour deposition (PECVD). The effect of input power on the chemical characteristics of the coatings has been studied by means of FT-IR and XPS analyses, while the plasma phase composition has been investigated by means of optical emission spectroscopy (OES) with actinometric analysis for some relevant species such as CN and NH. The effect of NH3 addition to bis(dimethylamino)dimethylsilane-Ar discharges has been considered in terms of film chemical composition and by performing a spectroscopic investigation of the plasma phase. Results indicate that dimethylaminosilanes are strongly fragmented, also under mild operating conditions, and that an important fragmentation step may involve NMe2 groups.