プラズマ診断は，プラズマプロセス中の荷電粒子の役割を理解する上で重要である．しかしながら，一般的なプラズマ診断は低圧の場合に限られているため，大気圧プラズマの特性を把握するためには新たな診断技術の開発が必要である．本論文では，ゲルディエンコンデンサーを用いた大気圧プラズマ診断を提案し，実用上十分な性能を有すことを実証した内容について報告している．さらに測定に影響を及ぼす要因についても調査した. / Plasma diagnostics plays an important part in understanding the role of charged particles during plasma processes. However, since common plasma diagnostic techniques are limited to low-pressure case, there is a need for the development of a new diagnostic method specifically for atmospheric pressure plasma characterization. In this dissertation, a diagnostic technique based on the Gerdien condenser theory is developed for laboratory-produced atmospheric pressure plasma. The Gerdien condenser, which is a classical instrument employed in atmospheric science, is capable in measuring the ion mobility and density from an obtained current-voltage characteristic. The factors that can affect the measurements are also investigated. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University

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Orientador: Konstantin Georgiev Kostov / Resumo: Nos últimos anos, tem intensificado o emprego de plasmas em pressão atmosférica para diferentes aplicações. Com o desenvolvimento dos jatos de plasma em pressão atmosférica, alguns tratamentos precisos, como no campo biomédico ou em específicos processamentos de superfícies, tornaram-se mais frequentes. No entanto, a aplicação de plasma à objetos irregulares, dentro de tubos ou mesmo dentro de órgãos ocos é limitada quando se utilizam configurações convencionais de jatos de plasma. Portanto, essas limitações podem ser superadas com o desenvolvimento de jatos de plasma alongados ou gerados remotamente. Neste trabalho, duas configurações de jato de plasma longo visando diferentes campos de aplicação foram aperfeiçoadas e caracterizadas. Inicialmente foi desenvolvido um jato de plasma endoscópico (plasma endoscope) operando em configuração de descarga por barreira dielétrica (DBD) com dimensões milimétricas, versátil ao acoplamento em endoscópios típicos. Este jato de plasma pode operar com hélio ou neônio e conta com um canal externo e concêntrico de gás que permite a introdução de uma cortina de gás eletronegativo ao redor da pluma de plasma. A cortina de proteção a gás preserva a forma do jato de plasma quando operado dentro de cavidades fechadas. As dificuldades advindas do desenvolvimento deste foram investigadas quando diferentes gases foram testados como cortina de proteção dele, dentre estes, o dióxido de carbono se mostrou uma boa opção evitando a formação de descargas ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The use of atmospheric pressure plasmas for different purposes has increased in recent years. With the development of atmospheric pressure plasma jets, some precise treatments such as in the biomedical field or specific surface processing became more often. However, the delivery of plasma to irregular shaped objects, inside tubes or even hollow organs is limited with the use of conventional plasma jet configurations. Therefore, those limitations can be surpassed with the development of elongated or remotely generated plasma jets. In this work, two extended plasma jet configurations aiming at different application fields were further developed and characterized. Firstly, an endoscopic plasma jet (plasma endoscope) operating with a dielectric barrier discharge (DBD) configuration in millimeter dimensions that can be coupled to a typical endoscope was developed. This plasma jet can operate with helium or neon and counts with an external concentric shielding gas channel that provides the introduction of an electronegative gas curtain around the plasma plume. The shielding gas allows the preservation of the plasma jet shape when operated inside closed cavities. The construction difficulties arisen from the use of different feed and shielding gases were explored. Carbon dioxide was proven to be a good option for the curtain gas around the plasma plume avoiding the formation of parasitic discharges inside the shielding gas tube and the endoscopic housing. When operated with neon, th... (Complete abstract click electronic access below) / Doutor

The role of a protein-repelling coating is to limit the interaction between a device and its physiological environment. Plasma-polymerized-PEG (pp-PEG) surfaces are of great interest since they are known to avoid protein adsorption. and cell attachment. However, in all the studies previously published in the literature, the PEG coatings have been prepared using low pressure processes. In this thesis, we synthesize biocompatible pp-PEG coatings using atmospheric pressure plasma. Two original methods are developed to obtain these pp-PEG films. 1. Atmospheric pressure plasma liquid deposition (APPLD) consists in the injection of the precursor, tetra(ethylene glycol)dimethylether (tetraglyme), by means of a liquid spray, directly in the post-discharge of an atmospheric argon plasma torch. 2. In atmospheric pressure plasma-enhanced chemical vapor deposition (APPECVD), tetraglyme vapors are brought in the post-discharge trough a heating sprinkler. The chemical composition, as well as the non-fouling properties of the APPLD and APPECVD films, are compared to those of PEG coatings synthesized by conventional low pressure plasma processes. In the first part of the study, the effect of the power on the chemical composition of the films has been investigated by infrared reflection absorption spectroscopy (IRRAS), X-ray photoelectron spectroscopy (XPS) and secondary ions mass spectroscopy (SIMS). The surface analysis reveals that for the APPECVD samples, the fragmentation of the precursor increases as the power of the treatment is increased. In other terms, the lower the plasma power is, the higher the “PEG character” of the resulting films is. Indeed, the C-O component (286.5 eV) of the XPS C 1s peak is decreasing while the hydrocarbon component (285 eV) is increasing as the power of the plasma is increased. The same conclusion can be drawn from the signature ToF-SIMS peaks (m/z = 45 (CH3OCH2+ and +CH2CH2OH), 59 (CH3OCH2CH2+), 103 (CH3(OCH2CH2)2+)) that are decreasing in the case of high power treatments. Accordingly, IRRAS measurements show that the C-O stretching band is decreasing for high power plasma deposition. This is in agreement with the observations made from the analysis of the LP PECVD coatings and from the literature. The films deposited by the APPLD process do not show the same behavior. Indeed, whatever the power injected into the discharge is, we are able to achieve films with a relatively high PEG character (83 %). The second part of this study is dedicated to the evaluation of the non-fouling properties of the coatings by exposing them to proteins (bovine serum albumin and human fibrinogen) and cells (mouse fibroblasts (L929 and MEF)) and controlling the adsorption with XPS (proteins) and SEM (cells). For the APPECVD samples, a low plasma power (30 W) leads to an important reduction of protein adsorption and cell adhesion (over 85%). However, higher-powered treatments tend to reduce the non-fouling ability of the surfaces (around 50% of reduction for a 80 W deposition). The same order of magnitude (over 90% reduction of the adsorption) is obtained for the APPLD surfaces, whatever is the power of the treatment. Those results show an important difference between the two processes in terms of power of the plasma treatment, and a strong relationship between the surface chemistry and the adsorption behavior: the more the PEG character is preserved, the more protein-repellent and cell-repellent is the surface. / Le rôle d’une couche empêchant l’adsorption de protéines est de limiter les interactions entre un implant et le milieu physiologique auquel il est exposé. Les films de poly(éthylène glycol) polymérisés par plasma (pp-PEG) sont d’intérêt majeur car ils sont connus pour empêcher l’adsorption de protéines ainsi que l’attachement cellulaire. Cependant, dans toutes les études publiées précédemment, les couches de type PEG ont été réalisées sous vide. Dans cette thèse de doctorat, nous synthétisons des couches de type pp-PEG biocompatibles par plasmas à pression atmosphérique. A cette fin, deux méthodes originales ont été développées. 1. La première méthode consiste en l’injection du précurseur, le tetra(éthylène glycol) diméthyl éther (tetraglyme), en phase liquide, en nébulisant ce dernier au moyen d’un spray, directement dans la post-décharge d’une torche à plasma atmosphérique fonctionnant à l’argon. En anglais, nous appelons ce procédé « Atmospheric pressure plasma liquid deposition (APPLD) ». 2. Dans la deuxième méthode, appelée en anglais « Atmospheric pressure plasma-enhanced chemical vapor deposition (APPECVD)», le tetraglyme est amené en phase vapeur dans la post-décharge, au moyen d’un diffuseur chauffant. La composition chimique des dépôts de type APPLD et APPECVD, ainsi que leurs propriétés d’anti-adsorption sont évaluées, et comparées aux dépôts pp-PEG obtenus par les méthodes à basse pression conventionnelles. Dans la première partie de cette étude, nous nous focalisons sur la composition chimique des films déposés, et plus particulièrement sur l’influence de la puissance injectée dans le plasma sur cette composition chimique. A cette fin, nous avons fait appel à des techniques d’analyse telles que la spectroscopie de réflexion-absorption infrarouge (IRRAS), la spectroscopie des photoélectrons X (XPS) et la spectrométrie de masse des ions secondaires (SIMS). Il en ressort que les films de type APPECVD perdent progressivement leur « caractère PEG » à mesure que la puissance de la décharge plasma est élevée. Cela serait dû à une plus grande fragmentation du précurseur dans la post-décharge d’un plasma plus énergétique. Cette tendance est cohérente avec ce que nous avons observé pour les dépôts à basse pression ainsi que dans la littérature. Dans le cas des films de type APPLD, un tel comportement n’a pas été mis en évidence : quelle que soit la puissance dissipée dans le plasma, les films présentent un « caractère PEG » relativement élevé. La deuxième partie de cette thèse est dédiée à l’évaluation des propriétés d’anti-adsorption des films synthétisés, en les exposant à des protéines (albumine de sérum bovin et fibrinogène humain) et des cellules (fibroblastes de souris, L929 et MEF). L’adsorption de protéines est contrôlée par XPS tandis que l’attachement cellulaire est contrôlé par imagerie SEM. Pour les échantillons de type APPECVD, un dépôt à faible puissance (30 W) mène à une importante réduction de l’adsorption de protéines et de cellules (> 85%) tandis qu’à de plus hautes puissances (80 W), l’anti-adsorption est sensiblement diminuée (50% de réduction). Dans le cas des dépôts de type APPLD, quelle que soit la puissance du plasma, une forte diminution de l’adsorption de protéines et de cellules est observée (> 90 %). Ces résultats montrent une différence majeure entre les deux procédés quant à l’influence de la puissance du plasma ainsi qu’une forte relation entre la composition chimique de la surface synthétisée et son pouvoir d’anti-adsorption : plus le « caractère PEG » du dépôt est conservé, plus la surface empêchera l’interaction avec les protéines et les cellules.

La réponse biologique d’un matériau est essentiellement reliée à sa surface : cela souligne l’importance du rôle des techniques de modification de surface dans la réalisation d’une réponse biologique adaptée. Ainsi les surfaces fonctionnalisées par des ‘hydrogels’ minces possèdent un énorme potentiel dans diverses applications. En effet, les hydrogels sensibles au pH et à la température peuvent être utilisés dans le but de libérer de façon contrôlée une molécule dans l’environnement biologique. Ces hydrogels peuvent aussi être utilisés en tant que biocapteur de par leurs fonctions disponibles permettant la reconnaissance spécifique de biomolécules cibles. Différents procédés, choisis principalement en fonction du type de matériau et de la surface à fonctionnaliser, peuvent être utilisés pour l’obtention de ce genre de films. Parmi ces procédés, le choix s’est tourné vers l’utilisation de la polymérisation par plasma dont les propriétés de surfaces peuvent être ajustées en fonction des paramètres de la décharge tel que la puissance électrique, le temps de traitement, la composition et la pression du gaz. / For various industrial applications, there is an urgent need to obtain cost effective coatings having the desired functional groups. Among such methods, dielectric barrier discharge (DBD) at atmospheric pressure makes it possible to modify the physical properties and the chemical composition of various substrates. It is possible to control the chemical nature of the resulting plasma polymer by using appropriate plasma parameters to provide homogeneous and pinhole free films with good surface coverage and preservation of the functional groups present in the used monomers. In this way different articles show the possibility of using plasma deposition to obtain coatings with different chemically reactive moieties widely used for applications in sensor technology and in life science. It has been established that through the control of the plasma parameters it is possible to produce plasma polymers coatings from acrylic acid with a high fraction of carboxylic functionality retained from the monomer. In this way, atmospheric pressure plasma polymerization has been used to create coating able to be used as biosensor as well as drug delivery.

Gegenstand dieser Arbeit war die Untersuchung antimikrobieller Dünnfilme mit Ag, Cu oder Zn, welche durch Anwendung einer Atmosphärendruck-Plasmatechnologie abgeschieden wurden. Bei der Abscheidung solcher Schichtsysteme ist von Wechselwirkungen zwischen dem Plasma und der Holzoberfläche auszugehen. Um solche Effekte abschätzen zu können wurden Versuche hinsichtlich makroskopischer, mikroskopischer und molekularer Materialeigenschaften durchgeführt. Diese Untersuchungen wurden primär mit dem Ziel durchgeführt, mögliche Wechselwirkungen zwischen dem reaktiven Plasma und Plasmabestandteilen mit der Oberfläche des Holzes besser zu verstehen und in zukünftigen Prozesses gezielt anwenden zu können. Unabhängig von der verwendeten Plasmaquelle und Holzart führten die Behandlungen zu einer verbesserten Benetzbarkeit der Holzoberfläche mit Wasser und zu einer deutlichen Erhöhung der polaren Komponente der Oberflächenenergie. Der Nachweis molekularer Veränderungen wurde durch ATR-FTIR- und XPS-Untersuchungen (einschließlich chemischer Derivatisierung) durchgeführt. Um den Einfluss von Holzinhaltsstoffen und Holzinhomogenitäten zu reduzieren, wurde der Einfluss auf die Holzbestandteile Cellulose und Lignin untersucht. Nach der Plasmabehandlung konnte die Bildung von O-C-Doppelbindungen durch ATR-FTIR für beide Materialien bestätigt werden. Die Bildung von sauerstoffhaltigen, polaren Funktionalitäten auf Cellulose und Lignin konnte auch durch XPSMessungen bestätigt werden. Die chemische Derivatisierung von Cellulose in Kombination mit XPS hat die Bildung von O-C-Doppelbindungen in Verbindung mit dem Abbau von OH-Gruppen aufgezeigt. Ein qualitativ vergleichbarer Behandlungseffekt konnte zwischen Plasma- und Ozonbehandlung nachgewiesen werden; Quantitativ waren die Plasmabehandlungseffekte jedoch deutlich ausgeprägter. Somit kann das vom Plasma gebildete Ozon nicht allein für den Behandlungseffekt verantwortlich sein, und weitere Reaktionsmechanismen müssen in die Interpretation der Ergebnisse einbezogen werden. Untersuchungen zur Abscheidung von SiO2- und TiO2 Schichten haben gezeigt, dass die Prozessparameter exakt angepasst werden müssen. Die Schichtqualität wurde maßgeblich durch die Wahl der chemischen Vorläufer und den Abstand zwischen dem Eintrittspunkt dieser Precursor und dem Substrat bestimmt. REM- und XPS-Untersuchungen bestätigten den Einbau der Elemente Ag, Cu oder Zn in nanopartikulärer Form in die Schichten. Die Abscheidung dieser Schichten auf Holz erzeugte signifikante bakterizide Eigenschaften gegen E. coli. Im Gegensatz dazu war die fungizide Wirkung gering. Durch die Wirkstoffkombination hingegen konnte eine deutliche Steigerung der Schimmelpilz-Mangeleigenschaften erreicht werden. Für mögliche Außenanwendungen und ausreichenden Schutz musste das Eindringen von Wasser in das Holz zusätzlich reduziert werden. Zu diesem Zweck wurden die funktionalisierten Plasmaschichten zusätzlich mit einer Deckschicht versehen. Der Plasmafilm übernahm dabei zwei wesentliche Aufgaben: die Haftung der Deckschicht und die Gewährleistung antimikrobieller Eigenschaften. Insbesondere die Verwendung des SiO2-Films in Verbindung mit einem Primersystem erhöhte die Nassschichthaftung deutlich. Das verwendete Schichtsystem (Plasmafilm + Deckschicht) zeigte sowohl unter künstlicher als auch bei natürlicher Witterung Vorteile gegenüber einem kommerziellen Schichtaufbau (Bläueschutzgrundierung + Decklack). Die Haftung der Deckschicht war nach künstlicher und natürlicher Bewitterung für Plasmaaufbau beständiger. Darüber hinaus zeigte die Plasmagrundierung hinsichtlich der Wirksamkeit des Bläueschutzes unter 11 monatiger natürlicher Bewitterung vergleichbare Eigenschaften im Vergleich zu der kommerziellen Grundierung. Werden die dabei eingesetzten Wirkstoffmengen betrachtet, war die eingebrachte Menge bei der Plasmagrundierung um einen Faktor von schätzungsweise 100-mal geringer als bei der Standardgrundierung. Die im Holzschutz eingesetzten Biozide verursachen hohe Kosten und sind gesundheits- und umweltschädigend. Vom Gesetzgeber wird deshalb gefordert, biozidfreie Alternativen anzuwenden bzw. Maßnahmen zur Minimierung des Biozideinsatzes zur ergreifen. In Folge dessen könnten mit Blick auf eine mögliche Anwendung die hohen Kosten des Einsatzes biozider Stoffe reduziert werden, eine Reduktion der Wirkstoffmenge aber auch zum Umweltschutz und zu einer höheren Akzeptanz bei Verbrauchern beitragen.:Abkürzungsverzeichnis IX Tabellenverzeichnis XI Abbildungsverzeichnis XII 1 Einleitung 1 1.1 Motivation 1 1.2 Zielstellung 2 1.3 Holz und Holzschutz 3 1.3.1 Aufbau und Bestandteile 3 1.3.2 Holzschädigung 4 1.3.3 Mikroorganismen 6 1.3.4 Holzschutz 7 1.4 Plasma 8 1.5 Technische Erzeugung kalter Atmosphärendruckplasmen 9 1.5.1 Atmosphärendruckplasmabehandlung von Holz und Holzbestandteilen 12 1.6 Schichtabscheidung mittels Atmosphärendruckplasma 15 1.6.1 Plasmapolymerisation und Schichtwachstum 16 1.6.2 Funktionelle Beschichtungen 17 1.6.3 Antimikrobielle Oberflächen 19 2 Material und Methoden 22 2.1 Geräte und Verbrauchsmaterial 22 2.2 Plasmaquellen 25 2.2.1 Behandlung 26 2.2.2 APP-CVD und Precursordosierung 27 2.3 Ozonbehandlung 28 2.4 Precursorauswahl 29 2.5 Instrumentelle Analytik 30 2.5.1 Kontaktwinkel und Oberflächenenergie 30 2.5.2 pH-Wert-Messung 32 2.5.3 Schichtdickenmessung 32 2.5.4 Fourier Transform Infrarot Spektroskopie (FT-IR) 33 2.5.5 Rasterelektronenmikroskopie (REM) 34 2.5.6 Röntgen-Photoelektronenspektroskopie (XPS) 35 2.6 Antimikrobielle Untersuchungen 39 2.6.1 BacTiter-Glo® 39 2.6.2 Plattenzählverfahren (KbE-Test) 41 2.6.3 Schimmelpilzbeständigkeit nach DIN EN 60068-2-10 41 2.6.4 Bläuebeständigkeit nach DIN EN 152:2012 42 2.7 Lackhaftung 43 2.7.1 Gitterschnittprüfung nach ISO 2409:2013 43 2.7.2 Künstliche Bewitterung nach EN 927-6 44 2.7.3 Freibewitterung nach EN 927-3 44 2.7.4 Farbveränderung 44 3 Einfluss von Plasma auf Holz 45 3.1 Charakteristika von Plasmaquelle und Material 45 3.2 Makroskopische Veränderungen 47 3.2.1 Kontaktwinkel- und Oberflächenenergiebestimmung 47 3.2.2 Allgemeiner Einfluss durch Atmosphärendruckbehandlung 52 3.2.3 Einfluss Substratmaterial auf Behandlungseffekt 54 3.2.4 Alterung und Extraktstoffeinfluss /Harzanteil 55 3.2.5 Einfluss Plasmasystem 57 3.2.6 Benetzbarkeit nach Ozonbehandlung 60 3.2.7 Einfluss von Plasmabeschichtungen 61 3.3 Änderung pH-Wert 63 3.5 Molekulare Veränderungen 65 3.5.1 ATR-FTIR an Textilzellstoff und Lignin 66 3.5.2 XPS: Sauerstoff/Kohlenstoff-Verhältnis 69 3.5.3 XPS: Nutzung der chemischen Derivatisierung 72 3.5.4 C1s-Detailspektren Textilzellstoff 79 3.5.5 C1s-Detailspektren Lignin 81 3.6 Fazit 86 4 Funktionelle Beschichtungen 87 4.1 Siliziumoxid- und Titanoxidmatrixschichten 87 4.2 Erweiterte Funktionalisierung (Kompositbeschichtungen) 89 4.3 Antimikrobielle Eigenschaften 94 4.4 Plasmagrundierung 103 4.4.1 Lackhaftung 103 4.4.2 Schichtleistung: Wasseraufnahme 107 4.4.3 Schichtleistung: künstliche und natürliche Bewitterung 107 4.4.4 Schichtleistung: antimikrobielle Wirkung 110 4.5 Fazit 112 5 Zusammenfassung 114 6 Ausblick 118 Literaturverzeichnis nach IEEE 119

Recently there has been a surge in the field of mass spectrometry centered around the concept of rapid analysis of target analytes with minimal or no sample preparation. The target analyte undergoes desorption from its surface of origin and is subsequently ionized under ambient conditions. The technique is termed ambient desorption/ionization mass spectrometry (ADI-MS). Since the introduction of ADI-MS in 2004, there has been an explosion of research based around the development of novel ambient desorption/ionization (ADI) sources with the capability of desorbing and ionizing a variety of target analytes from various sampling surfaces. One type of ADI source uses the properties of an electrical discharge, typically a helium gas plasma, for desorption and ionization. For electrical-discharge-based sources, ionization is the result of an atmospheric pressure chemical ionization (APCI) process. The initiation of the APCI process it generally attributed to the Penning ionization of atmospheric nitrogen (N2) by highly energetic helium metastable species (Hem). In this work, I describe the direct imaging of the densities of helium metastable atoms in atmospheric pressure plasma jet (APPJ) of a helium-based dielectric-barrier discharge (DBD) using collisionally-assisted laser-induced fluorescence. Axial Hem distributions are compared to the emission of excited helium (He*) and nitrogen ion (N2+*) species in the plasma. A correlation is found between Hem densities and the performance of the ionization source in ADI-MS. Fluorescence images also show that Hem densities increase substantially when a glass slide is placed 10 mm from the discharge capillary in a geometry typical for desorption/ionization experiments. Advantage is taken of the time-varying nature of the plasma to produce axial profiles of temporally and spectrally resolved fluorescence images of Hem atoms and ground state nitrogen ions in the plasma jet. The axial distribution and similarities in the temporal behavior of the helium metastable and ground state nitrogen ion species give strong evidence that nitrogen ion species are created via Penning ionization by helium metastable atoms. Although axial distributions of He*,N2+*, and N2* emission support the fluorescence data, temporally-resolved emission measurements show that emission from key plasma species is almost entirely the result of excitation by a temporal energy wave. The effect that hydrogen (H2) has on the helium metastable atom densities is also presented. The addition of hydrogen to the discharge gas severely quenches the metastable state, leaving it virtually undetectable. The addition of 0.9% H2 to the helium in the source provides an order of magnitude increase in ADI-MS signal for target analytes despite the quenching of the Hem population.

Yes / Antioxidant active packaging was prepared by coating a citrus extract on the surface of polyethylene terephthalate (PET) trays which had been either treated with an atmospheric pressure plasma jet or left untreated. The surface characteristics of the packaging were examined, as were its stability and antioxidant efficacy following storage for up to 24 weeks under the following three storage conditions: room temperature, 0 % relative humidity (RH) or 50 °C. Plasma pretreatment increased coating density, thickness and roughness, and oxygenated functional groups at the polymer surface, whereas water contact angle decreased. Trays stored at room temperature did not lose their antioxidant efficacy over 24 weeks and plasma pretreatment enhanced the efficacy from week 8 onwards. Gravimetric analysis of the coating revealed a loss of antioxidant compounds only after 16 weeks. Trays stored at 0 % RH lost coating from week 1 onwards, with lower loss in plasma pretreated trays, while loss of coating was highest at 50 °C, with lower loss in plasma pretreated trays only after 24 weeks. Overall, the surface characteristics of the antioxidant active packaging were modified by plasma pretreatment of the PET surface, with some improvement in antioxidant efficacy, and the efficacy of the packaging in delaying oxidative deterioration in cooked meats was retained during storage at ambient temperature.

Damages of metallic aircraft structures that occur during manufacturing, assembly and in service require local repair. Especially with current service-life extensions of ageing aircraft fleets, the importance of such repair methods is increasing. Typically, the repair of smaller damages on aluminium fuselage or wing skins is done by riveting a patch onto the flawed structure. However, the use of rivets reduces the strength of the structure and promotes fatigue. Joining the patch by adhesive bonding would not only offer more homogenous load distribution and weight savings, but even an increase of structural integrity. Metal adhesive bonding is commonly used in aeronautics, but requires elaborated surface treatments of the adherends, employing hazardous chemicals like chromates, due to the high durability demands. Furthermore, these treatments are usually tank processes that are not suitable for local repairs. Hence, there is a strong need for locally applicable surface preparation methods that allow safe and reliable adhesive bonding of primary aircraft structures. The aim of this thesis is to assess the – still emerging – method of atmospheric pressure plasma deposition of silicon (Si) containing compounds concerning its suitability as surface preparation for adhesive bonding of aluminium aerostructures. Atmospheric plasma deposition is not yet used in the aircraft industry, and the knowledge on functionality of this technology concerning bonding of aluminium parts is limited. Moreover, the durability requirements of the aircraft industry greatly exceed the standards in other industries. Hence, special attention is paid to a thorough analysis of the key characteristics of the deposited coupling films and their effectiveness in terms of adhesion promotion as well as joint durability under particularly hostile conditions. In order to do so, the altering mechanisms of the treated joints and the behaviour of the coupling films during accelerated ageing will be investigated in detail for the first time in this thesis. Furthermore, the influence of the aluminium surface pre-treatment (i.e. topography and oxide properties of the substrate) on the overall joint performance after coupling film deposition is thoroughly examined. Based on these findings, the surface preparation is optimised, and a process is developed to achieve maximal joint performance. As alternative local surface treatments prior to adhesive bonding, solution derived deposition of silane and sol-gel films have already been widely investigated and can be considered as reference, even though these techniques are rarely used in civil aeronautics. The knowledge on their effectiveness and capabilities in corrosive atmosphere is still very limited. Therefore, all analyses of degradation mechanisms are conducted for both plasma deposition and wet-chemical reference treatments to reveal the differences and communalities of the two Si-based coupling films. Physical and chemical analysis of the films, the oxides and the interfaces reveal differing, but interdependent failure mechanisms that are inhibited differently by the individual coupling films. Using the optimum deposition parameters, plasma films of only several nanometres in thickness significantly enlarge the corrosion resistance of bonded joints, reaching almost the level of anodising treatments with several micrometres thick oxides and strongly outperforming solution derived silane treatments. However, plasma film performance is found to be largely dependent on the precursor selection. With plasma deposition of 3-glycidoxypropyltrimethoxysilane, which has not been reported before, highest joint stability is achieved. Moreover, it is discovered that the properties of plasma and solution derived silane based films are complementary. It is shown that an optimised combined plasma and wet-chemical treatment process provides even superior resistance to bondline corrosion than state-of-the-art anodising techniques.

The aim of this thesis is to investigate the properties of a Radio Frequency capacitive discharge at atmospheric pressure in argon. In these conditions where the pressure x distance product is around 150 Torr.cm, the discharge usually consists of several locally hot filaments. By pulsing the RF generator with an appropriate width and period, it was found possible to control the filament to glow transition in order to obtain a diffused and stable plasma.¶ The 2 mm gap between the electrodes is open to the ambient air and fed with argon via one hundred submillimetric holes regularly spread on the surface of the top electrode. This configuration allows “on-line” surface treatment of polymer films without having to turn the discharge off between successive samples. An important and lasting improvement of the polymer wettability is quickly obtained without risk of damage. The plasma diagnostic methods are emission spectroscopy and electric measurements. The Stark broadening of the Balmer β transition line of atomic hydrogen is measured to determine a plasma density of 10^15/cm3 in the filamentary mode. The glow mode density estimation was based on power balance yielding a density of 5×10^11/cm3. Emission line ratios between neutrals and Ar+ ions are used in the Saha equation to calculate the electron temperature. It results in an approximation of 1.3 eV for the glow mode and 1.7 eV for the filaments.¶ A unidimensional self-consistent fluid model is developed to gain insight into the homogeneous discharge behaviour. Poisson’s equation for the electric field is coupled to the first moments of the Boltzmann equation (continuity equation, drift-diffusion equation and energy equation). Transport and reaction coefficients are obtained from the mean energy of the electrons.¶ The model is applied to a reduced argon kinetic with the main ionization and excitation processes. Simulation results are in agreement with experimental measurements. The atmospheric pressure RF discharge is similar to a lower pressure RF discharge for which the ionization occurs mainly inside the oscillating sheaths where electrons are the most energetic