This thesis deals with ionic liquids and use of ionic liquids as electrolytes in lithium-ion batteries. Thesis describes basic characteristics of secondary electrochemical cells and characteristics of ionic liquids. Thesis also describes modifications and measurement of ionic liquids. Thesis also presents the results of measurement conductivity and potential window of modified ionic liquids.

This work deals with the corrosion protection of magnesium alloy AZ31, AZ61, AZ91 using fluoride conversion coating prepared from Na[BF4] melt. The theoretical part describes the properties of magnesium alloys, the recent results of fluoride conversion coatings preparation and analysis of the available literature about the properties of salt Na[BF4] and its decomposition products. The experimental part was devided into two main sections. The first deals with the corrosion resistance of the treated magnesium alloys (AZ31, AZ61, AZ91 and AZ91 annealed) in the Na[BF4] melt. Corrosion resistance was tested using potentiodynamic tests and tests in the corrosion chamber. In the second part, the mechanism has been studied for preparing fluoride conversion coating, where it was shown that in air-free atmosphere the oxidizing agent in the process is boron, which is reduced from BIII to B0, and thereby enables the fluoride conversion coating.

Submitted by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-30T13:47:33Z No. of bitstreams: 1 DIS_ANDRE_LUIZ_ANTON_DE_SOUZA_COMPLETO.pdf: 1015461 bytes, checksum: 70dfda26cefa98999779334ff862f5c0 (MD5) / Made available in DSpace on 2017-06-30T13:47:33Z (GMT). No. of bitstreams: 1 DIS_ANDRE_LUIZ_ANTON_DE_SOUZA_COMPLETO.pdf: 1015461 bytes, checksum: 70dfda26cefa98999779334ff862f5c0 (MD5) Previous issue date: 2017-03-23 / In recent years the scientific community has a growing interest in studying environmentally friendly agents sorption of carbon dioxide to be used in substitution of chemical solvents based on amines. Among the technologies studied for this purpose are those which use Ionic liquids that have the advantage of having very low vapor pressures, higher density than water, a low melting point and a desorption low energy; These qualities that make them environmentally friendly solvents, compared with volatile organic solvents. Moreover ionic liquids are chemically and thermally stable and can be used at relatively high temperatures, its physical-chemical properties can be designed by varying the substitutive groups of the cation or the combined ion. These characteristics make ionic liquids potentially important for the development of new processes focused on the mitigation of global warming. Otherwise the ionic liquids have a high viscosity, they are expensive making them economically unfeasible for use in conventional processes with liquid gas absorption columns. On the other side are available in the market the bubble glass that have several applications in the industry, have low cost, high chemical and physical resistance. This work evaluated in isochoric saturation cell, the carbon dioxide solubility in mixed systems with boron silicate bubble glass, with volumetric concentrations of 5% to 50%, in the ionic liquids [Bmim][BF4] and [mBmim] [NTf2] as well as with pure ionic liquids. Data are reported at 27 Bar pressure and at temperatures 303, 313, and 323 K. Mixed systems with 50% concentration of bubble glass showed the best results of sorption and cost for both ionic liquids. / Nos ?ltimos anos existe na comunidade cient?fica um crescente interesse em estudar agentes de sor??o de di?xido de carbono ambientalmente amig?veis para serem utilizados em substitui??o aos solventes qu?micos baseados em aminas. Entre as tecnologias estudadas para este fim est?o aquelas que utilizam os l?quidos I?nicos (LI). Estes compostos apresentam como caracter?stica diferencial baix?ssima press?o de vapor, densidade maior que a da ?gua, baixo ponto de fus?o e baixa energia de regenera??o; qualidades estas que os tornam solventes ambientalmente amig?veis quando comparados com os solventes org?nicos vol?teis. Por?m a alta viscosidade e custo limitam o uso dos Lis. Estudos realizados com sistemas mistos de LIs e part?culas s?lidas tem mostrado que tais part?culas podem potencializar a a??o dos Lis, assim se identificou as microesferas de vidro, dispon?veis no mercado, onde possuem diversas aplica??es na ind?stria, baixo custo, alta resist?ncia qu?mica e f?sica. Neste trabalho foram avaliados sistemas mistos (Lis + microesferas de vidro boro silicato) visando melhorar as propriedades dos Lis. Para avaliar estes novos sistemas foram obtidos em c?lula de satura??o isoc?rica, dados experimentais de solubilidade do di?xido de carbono, nas concentra??es volum?tricas de 5% a 50%. Foram avaliados os LIs [Bmim] [BF4] e [mBmim] [NTf2] para obter os sistemas mistos, assim como puros. Os dados s?o reportados na press?o de 27 Bar e nas temperaturas 303, 313, e 323 K. Os sistemas mistos com concentra??o de 50% de microesferas apresentaram os melhores resultados combinados de capacidade de sor??o e custo para ambos os l?quidos i?nicos.

The submitted work is aimed at the unconventional fluoride conversation coating preparation on the AZ31, AZ61, ZE10 and ZE41 magnesium alloys by their immersion in Na[BF4] molten salt. The influence of the preparation parameters (such as temperature and time) on the quality of the fluoride conversion coating is investigated. Methods of light and scanning electron microscopy were used for the evaluation of morphology, chemical composition and thickness of the coating. Short and long-term corrosion tests were executed to analyze the corrosion performance in simulated body fluid solution at 37 ± 2 °C with and without the fluoride conversion coating. The short-term behavior was evaluated by potentiodynamic tests, namely by the linear polarization. Long-term performance was assessed by electrochemical impedance spectroscopy or immersion tests. The coating preparation parameters influence on the character of the formed fluoride conversion coating was defined based on the obtained results. The next part of the thesis deals with the description of the possible mechanism of formation and kinetics of growth of the unconventional fluoride conversion coating on the selected AZ61 magnesium alloy. In this part, further detailed analyses were carried out to investigate the microstructure and chemical composition of the fluoride conversion coating using focused ion beam, transmission electron microscopy and X-ray photoelectron spectroscopy.