The main topic of this Diploma thesis is the application of low-pressure low-temperature hydrogen plasma for the treatment model samples of rusted brass. Plasmachemical treatment of metallic artifacts is a relatively new way how to remove corrosion of artifacts. The temperature of an object should not exceed 150 °C during the treatment. Corrosion layers were prepared in an ammoniac corrosion atmosphere. The corrosion formation took two weeks. Energy Dispersive X-ray Microanalysis has shown that the corrosion layer was formed by carbon, oxygen, copper, zinc, and lead. The corrosion layers were blue-colored with white crystals on the surface. Except those two colors, brown color was observed on corrosion layers, too. The plasma reactor was a quartz tube with outer copper electrodes and supplied by the RF source of 13.54 MHz. The reactive atomic hydrogen was formed in plasma discharge. This atomic hydrogen reacted with the corrosive layer containing oxygen. This reaction created an unstable OH radical, which emitted light in the region of 305–320 nm. This radiation was detected by the optical emission spectroscopy and it was applied as process monitoring quantity. Rotational temperature and intensity of OH radicals were determined from obtained data. The sample temperature was measured by thermocouple installed inside the sample volume. Rusted samples were treated by low-pressure low-temperature hydrogen plasma. 16 samples were treated at different conditions – plasma power was 100 W, 200 W, 300 W, and 400 W at continuous mode and pulse mode with duty cycle of 25 %, 50 %, and 75 %. The pressure was between 140–160 Pa at hydrogen flow rate of 50 sccm. Samples after plasmachemical treatment were grey colored with white crystals on their surface. Corrosion layers were removed by spatula. The corrosion layers of some samples were easy removable, some others were difficult. Energy Dispersive X-ray Microanalysis, which was carried out after the treatment of 2 selected samples (400 W, 50% pulse mode and 400 W, 75% pulse mode), showed different amounts of carbon, oxygen, copper, zinc, and lead compared to the rusted sample. Other elements in the treated layer were silicon, sulfur, chlorine, and fluorine.

This diploma thesis is focused to the plasma chemical reduction of model corrosion layers prepared on bronze samples. Bronze was the main material for production of the subjects in Bronze Age. First, it was very rare, and therefore was used only for making jewellery and other decorative subjects. Later, the objects of daily use and weapons were produced of bronze. These objects are found and it is necessary to restore him and preserve the cultural heritage for future generations. The research and the optimalization of plasmochemical reduction of model corrosion layers on bronze samples contributes to this. A metallographic grinder was used to create a defined surface, first with the sandpaper P 280 and then after sample 90 degree rotation with the sandpaper P 600. This ensured uniform surface at all bronze samples that is necessary to provide the same corrosion conditions. The grinded samples were washed by ethanol and dried by hot air stream. To prevent contact with the surrounding atmosphere and successive initiation of corrosion, the samples were stored in lockable polyethylene bags. This step was followed by the preparation of model corrosion layers. Hydrochloric and sulfuric acids were chosen as corrosive environments. Petri dish containing 20 ml of the selected acid was placed at the bottom of the desiccator. Samples were placed to the ceramic grate, over the dish, and they were corroded (in vapours of hydrochloric acid for 34 days and in vapours of sulfuric acid for 27 days). The corroded samples were treated using low-pressure hydrogen plasma excited by RF generator. Treatment of samples was carried out in quartz cylindrical reactor (length of 90 cm, inner diameter 9.5 cm) with copper electrodes placed outside. The pressure in the reactor was ranged around 160 Pa at hydrogen flow rate of 50 sccm during the experiments. The continuous and pulse modes (duty cycle of 25%, 50% or 75%) at peak power of 50–300 watts were used for the treatment of 90 minutes duration. The plasma treatment was monitored by optical emission spectroscopy of OH radical using compact Ocean Optics HR4000 spectrometer. Its integral intensity is proportional to the corrosion layer removal. The rotational temperatures of plasma were calculated using selected OH rotational lines, too. The sample temperature during the treatment was measured by thermocouple installed inside the additional non-corroded samples. The reduction of corrosion layer is successful when the maximum of relative intensity of OH radicals is produced and follow gradual decline. The samples which corroded in vapours of sulphuric acid and were treated in pulse modes with duty cycle of 25 % or with delivered power of 50 W has produced no maximum. To the remain samples the maximum although were observed, but reduced corrosion products on the surface were very cohesive. The maximum of relative intensity of OH radicals was observed at all samples corroded in vapours of hydrochloric acid. But there is problem with temperature of sample during experiment. The samples which layer of corrosion product was after experiment incoherent produced the layer of deposit tin. This effect formation at a higher temperature of sample during experiment and therefore with greater deliver energy.

The presented Thesis deals on the nitrogen-hydrogen DC post-discharge observations by optical emission spectroscopy. The plasma was generated in Pyrex tube in flowing regime at pressure of 1 kPa at discharge current of 100 mA. The optical emission spectra were recovered at discharge times up to 50 ms in nitrogen containing 0 – 92 % of hydrogen; the gas mixture volume, i.e. the gas speed in the system was conserved for all mixtures. The experiments were carried out at two reactor wall temperatures at the spectra collecting point – at ambient temperature and at the wall temperature of liquid nitrogen (temperature in plasma was about 150 K). The nitrogen first and second positive and first negative spectral systems were identified in the spectra, the hydrogen atomic Balmer series lines were recorded, too. No molecular hydrogen emission was determined during the post-discharge. Some non-identified bands (but with high probability bands of nitrogen Herman infrared system) at 690 and 780 nm were detected, too, mainly at low temperature. The intensities of all determined radiating species decreased exponentially or more than exponentially with the decay time. The experimental data showed strong quenching of all nitrogen radiative states even at very a few percent hydrogen additions. The shape of the selected intensity dependencies on both hydrogen concentration, and the decay time are nearly the same for N2(C) and N2+(B) states, dependencies for N2(B) levels differs of them. The hydrogen line emission was nearly independent on the hydrogen content in the gas mixture up to about 50%, at highest hydrogen concentrations it slightly increased. The results obtained at the decreased wall temperature were very similar, only intensities of all nitrogen spectra increased by the factor about 3, the intensities of levels populated by the recombination of nitrogen atoms increased by factor about five. The atomic hydrogen alpha line (at 656 nm) was the most sensitive on temperature decrease; its intensity increased over one order in whole observed time interval. The obtained results will be confronted with numeric model of kinetic processes in the near future. After that, the specific conditions applicable for the technological applications of nitrogen-hydrogen gas mixtures under post-discharge conditions will be proposed.

Thin films have been used to modify surface properties of various materials for many years. Plasma Enhanced Chemical Vapor Deposition (PECVD) is one of the possible methods for their preparation and this technique is applied in this work as well. An organosilicone – hexamethyldisiloxane – is used as precursor. Thin films are created on the surface of the substrate using mixture of precursor and oxygen in radiofrequently excited capacitively coupled plasma. The aim of the thesis is to find the optimal deposition conditions for production of transparent thin layers with good barrier capabilities, low oxygen transmission rate especially. Thin film depositions were realized for different compositions of the deposition mixture in continuous and pulsed mode of plasma with varying supplied power and duty cycle values. The deposition process itself was monitored in situ by optical emission spectroscopy. Thin film coatings were analyzed to determine their physical chemical properties (infrared spectroscopy, surface energy) and barrier properties. Using optical emission spectroscopy, important particles were identified in the deposition plasma. Vibrational, rotational and electron temperatures were determined from relative intensities of chosen fragments. Composition of thin films was studied by infrared spectroscopy. The best results of oxygen transmission rate were achieved with layers prepared from deposition mixture with high oxygen content. It was possible to improve barrier properties by performing deposition in pulsed plasma mode with 20–30% duty cycle. In this diploma thesis, optimal deposition conditions of thin films from hexamethyldisiloxane with low oxygen transmission rate were determined. It is possible to use these results in practical applications, such as corrosion inhibitors for archaeological objects. Optionally, they can be used in various industry branches where it is desirable and feasible to prevent oxygen access to the material by deposition of barrier coatings.

This master thesis deals with determination of temperature field in a real circuit breaker. This issue is solved by analysis of measured emission spectra at selected points of the circuit breaker. Spectral line ratios and Boltzmann plot are used for calculation of temperature. These methods are based on elemental analysis of plasma. The main result is finding significant changing of chemical composition of plasma beyond determination of temperature field.

Multielement analysis of flue gas residues from secondary lead smelting was tested using seven decomposition methods on four different flue gas residues and certified reference materials (CRM) CPB-2 (Pb concentrate, CCRMP). The studied samples contained both silicates and also high contents of phases with Pb, primarily Pb chlorides and sulphates. Solutions prepared by various decomposition methods were analysed using ICP OES (Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Sb, Se, Si, Sn, Sr, Ti, Tl, V, Zn). Greater yields were found for most of the elements by combined decomposition (with fusion) and decomposition by sintering. Nonetheless, both methods exhibited major losses of volatile elements (As, Bi, Sb, Tl). Thus, one of these methods must always be combined with a method of decomposition in a closed system. The work also demonstrates that, for investigation of untraditional waste geological materials (e.g. flue residues from high- temperature industrial processes), it will be necessary in the future to produce new certified reference materials with anomalous chemical and mineralogical compositions, which are not currently available on the market. Laboratory extraction tests were performed on two different types of flue residues - kinetic (30 days) with ratio L/S...

Les matériaux (nano)composites font partie intégrante de l’industrie de l’aéronautique et de l’espace depuis plus de 50 ans. De nos jours, le concept de matériaux multifonctionnels combinant diverses propriétés pour réaliser des objectifs de performance multiples en un seul et unique système est devenu une exigence pour le développement de surfaces innovantes, et ce, pour une vaste gamme d’applications technologiques. Cependant, pour plusieurs applications, un des principaux verrous est l’obtention de revêtements formés de nanoparticules isolées (non-agrégées) et de petite taille (<10 nm) dispersées de manière contrôlée dans une matrice. Dans ce contexte, une nouvelle méthode de synthèse souple, verte, sécuritaire et industrialisable a récemment été proposée. Celle-ci repose sur un réacteur-injecteur de nanoparticules et permet de synthétiser des nanoparticules à partir de précurseurs organométalliques liquides juste avant de les injecter dans un réacteur de dépôt par plasma en limitant les phénomènes d’agglomération associés à la vaporisation de gouttelettes et en évitant les problèmes de toxicité éventuelle en lien avec la manipulation de nanoparticules avant le dépôt. Cependant, contrairement aux procédés de dépôt par plasma habituels qui s’effectuent la plupart du temps à pression constante, la conception du réacteur-injecteur de nanoparticules implique inévitablement une dynamique temporelle complexe associée à des variations assez brutales de la pression dans le réacteur à plasma. À l’évidence, ces variations temporelles de pressions vont se répercuter sur l’évolution temporelle des propriétés fondamentales du plasma telles que la densité et la température des électrons. Dans ce travail de maîtrise, nous avons eu recours à la spectroscopie optique d’émission couplée aux prédictions de modèles collisionnels-radiatifs pour déterminer des conditions opératoires du réacteur-injecteur dans un plasma rf d’argon minimisant ces variations d’une part, et permettant de mieux comprendre leurs implications sur la température des électrons, d’autre part. Ces travaux serviront ainsi d’effet levier à des études plus complexes en présence de précurseurs et de nanoparticules. / (Nano) Composite materials have been an integral part of the aeronautics and space industry for more than 50 years. Nowadays, the concept of multifunctional materials combining various properties to achieve multiple performance objectives in a single system has become a prerogative in the development of innovative surfaces for a wide range of technological applications. However, for several applications, one of the main challenges is the production of coatings formed of isolated (non-aggregated) and small (<10 nm) nanoparticles dispersed in a controlled manner in a matrix. In this context, a new flexible, green, safe and scalable method of synthesis has recently been proposed. It is based on a reactor-injector of nanoparticles and can synthesize nanoparticles from liquid organometallic precursors just before injecting them into a plasma deposition reactor by limiting the agglomeration phenomena associated with the vaporization of droplets and by avoiding problems of possible toxicity related to the manipulation of nanoparticles before the deposit. However, unlike conventional plasma deposition processes, which are usually carried out at constant pressure, the design of the reactor-injector of nanoparticles inevitably involves a complex temporal dynamic associated with rather sudden changes in the pressure in the plasma reactor. Obviously, these temporal variations of pressures will affect the temporal evolution of the fundamental properties of the plasma such as the density and the temperature of the electrons. In this master work, we used optical emission spectroscopy coupled with the predictions of collisional-radiative models to determine operating conditions of the reactor-injector in an argon rf plasma minimizing these variations on the one hand, and to better understand their implications on the electron temperature, on the other hand. This work can thus be expected to serve as building blocks for more complex studies in the presence of precursors and nanoparticles.

Study of plasma in the mixtures with molecular gas at wide pressure range Matěj Jan Morávek Abstract: The positive column of DC glow discharge sustained in oxygen and oxygen-nitrogen mixtures has been studied in two discharge tubes of the same shape made from different materials (Silica and Pyrex glass) for total pressures 650 - 2000 Pa and discharge currents up to 40 mA. Various parameters of the discharge - axial electric field strength, concentration of electrons and emission spectra - were studied with emphasis placed on transition region between low- and high-gradient form of the positive column. We have focused on the qualitative and quantitative analysis of the differences in emission spectra for both particular forms and the transitional region between them. The impact of 1 % admixture of nitrogen was also studied.

The aim of this thesis is a study of processes during organosilicone thin film deposition via plasma polymerization. Recently, thin films are the most expanding way of surface modification of materials. They are used as protective coatings, functional layers, they can increase or decrease adhesion to different compounds (e.g. water), or just improve mechanical properties of bulk materials. Plasma polymers, which are not known so long, are a modern trend in evolution of thin film deposition. They have perfect adhesion to the substrate and they are highly resistant against most of chemical compounds. Their structure is quite different from the structure of classical polymers. Recently, organosilicon compounds are used as precursors for plasma polymers because silicon built in the structure of plasma polymer allows thin film deposition on glass substrate and the organic part of monomer gives us infinite possibilities of modification. In our case dimethylphenylsilane (DMPS) was used as a monomer. Various RF low pressure discharges were used during this study. Plasma diagnostic was performed by optical emission spectroscopy of inductive coupled plasma. This method allows us to determine plasma composition during the deposition process. Thus we can predict the composition of deposited thin film according to input parameters. From relative populations of fragments we are able to find out optimal conditions for deposition process. We can also calculate temperature of particles in plasma which gives us some information about particle energies. The first part of the study deals with the identification of particles (fragments) created by fragmentation of monomer in plasma environment. We successfully identified hydrogen atomic lines of Balmer’s series in the spectra. Many rotational lines of hydrogen molecule were also detected. Atomic carbon occurred only in small amount. Much more carbon was detected in the form of CH radical. We also found some weak lines connected to atomic silicon. When we used a mixture of DMPS and oxygen, OH radical and O2+ were present in spectra. Next, optimal settings of deposition were determined for particular fragments from relative intensities of these fragments in optical emission spectra. Using this information we are able to set up the process to deposit thin films of desired composition and properties. We calculated electron temperature from intensities of hydrogen lines in Balmer’s series. Rotational temperature was obtained from CH radical intensity. Unfortunately, there was no convenient radical from which intensity we would be able to calculate vibrational temperature. All results and information obtained during the research can be used in industrial plasma polymerization processes and development of new coatings and functional thin films. Other studies on DMPS or similar monomer may also be realized to get more knowledge about processes in plasma and this thesis could serve as a basis for further research. Moreover, this study is a part of an international project. The aim of this project is to study processes during plasma polymerization both theoretically and practically. Once finished, the project and its results will be presented in scientific literature and at international conferences.

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