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Nanocomposites of multilayer structures of zirconia/polymer thin-film coatings have been fabricated on quartz and single-crystal silicon substrates by the Ionically Self-Assembled Monolayer (ISAM) technique. Particle size distribution was measured to calculate the grain diameter of the zirconia particles. UV/Vis spectroscopy and ellipsometry were used to characterize the ISAM technique. SEM and AFM were used to observe the microscopic structure of the multilayer structures. Some mechanical properties were characterized by adhesion, abrasion, and nano-hardness tests. It was shown that an important distinction of this novel technique over conventional coating processes is the fabrication of excellent molecular-level uniform films with precise control of film thickness at the à ngström-level at ambient temperature and pressure conditions. It was also shown the maximum Vickers microhardness of ZrO2/polymer nanocomposite thin-film coatings prepared by this method was greater than 25 GPa. / Master of Science

O objetivo principal deste trabalho é a caracterização cristalográfica da zircônia co-estabilizada com ítria e magnésia, aplicando o método de Rietveld aos dados de difração de raios X, para a análise quantitativa de fases dos polimorfos da zircônia (monoclínica, tetragonal e cúbica ). As amostras de zircônica foram obtidas com dopagem de óxidos de magnésia e ítria, com concentrações molares definidas. Sua estabilidade durante o recozimento subeutetóide a 13500C foram determinados para investigar a degradação das fases ZrO2 - MgO - Y203 e definir o ambiente de estabilidade de soluções sólidas. A quantidade relativa de polimorfos cúbico, tetragonal e monoclínico de Zr O2, presentes em amostras de dopadas com 8 mol % de MgO e 1 mol % de Y2O3 e 9 mol % de MgO e 0 mol% de Y2 O3 foram determinadas por difração R-X, utilizando o método de Rietveld. As amostras foram calcinadas a 5500C, sinterizadas a 15500C, com envelhecimento a 13500C por 1h, 2h, 4h, 16hs, respectivamente e caracterizadas pelo método de Rietveld usando dados obtidos por difração de raios X. A variação no parâmetro de rede, a composição das fases e a microestrutura são discutidas. A análise revelou em todas as amostras que não houve indicação da formação da fase tetragonal, e que nas amostras dopadas com 1% de ítria, ocorre redução da transformação para a fase monoclínica durante o envelhecimento. / The key objective of this work is the crystallographic characterization of the zircon co-doped with yttria and magnesium with the application of the Rietveld method for quantitative phase analysis of zircon polymorphs (zircon monoclinic, tetragonal, and cubic). Samples of zircon polymorphs were obtained from zircon doped with yttria and magnesium at defined molar concentrations. The zircon polymorphs stability during subeutetoid aging at 13500C were investigated to determine ZrO2 - MgO - Y203 phases degradation and to define the solid solutions stability environment. ZrO2 powders doped with 8 mol% of MgO and 1 mol% of Y2O3, and 9 mol% of MgO and 0 mol% of Y2O3 have been prepared by chemical route using the co-precipitation method. These samples have been calcinated at 550 °C, sintered at 15000C and characterized by the Rietveld method using the X-ray diffraction data. The variation of the lattice parameter, changes in the phase composition and their microstructures are discussed. The application of the Rietveld method for quantitative phase analysis of zircon polymorphs (zircon tetragonal and cubic) reveals no formation of tetragonal phase and indicating that the matrix is the cubic phase with low concentration of monoclinic phase.

O objetivo principal deste trabalho é a caracterização cristalográfica da zircônia co-estabilizada com ítria e magnésia, aplicando o método de Rietveld aos dados de difração de raios X, para a análise quantitativa de fases dos polimorfos da zircônia (monoclínica, tetragonal e cúbica ). As amostras de zircônica foram obtidas com dopagem de óxidos de magnésia e ítria, com concentrações molares definidas. Sua estabilidade durante o recozimento subeutetóide a 13500C foram determinados para investigar a degradação das fases ZrO2 - MgO - Y203 e definir o ambiente de estabilidade de soluções sólidas. A quantidade relativa de polimorfos cúbico, tetragonal e monoclínico de Zr O2, presentes em amostras de dopadas com 8 mol % de MgO e 1 mol % de Y2O3 e 9 mol % de MgO e 0 mol% de Y2 O3 foram determinadas por difração R-X, utilizando o método de Rietveld. As amostras foram calcinadas a 5500C, sinterizadas a 15500C, com envelhecimento a 13500C por 1h, 2h, 4h, 16hs, respectivamente e caracterizadas pelo método de Rietveld usando dados obtidos por difração de raios X. A variação no parâmetro de rede, a composição das fases e a microestrutura são discutidas. A análise revelou em todas as amostras que não houve indicação da formação da fase tetragonal, e que nas amostras dopadas com 1% de ítria, ocorre redução da transformação para a fase monoclínica durante o envelhecimento. / The key objective of this work is the crystallographic characterization of the zircon co-doped with yttria and magnesium with the application of the Rietveld method for quantitative phase analysis of zircon polymorphs (zircon monoclinic, tetragonal, and cubic). Samples of zircon polymorphs were obtained from zircon doped with yttria and magnesium at defined molar concentrations. The zircon polymorphs stability during subeutetoid aging at 13500C were investigated to determine ZrO2 - MgO - Y203 phases degradation and to define the solid solutions stability environment. ZrO2 powders doped with 8 mol% of MgO and 1 mol% of Y2O3, and 9 mol% of MgO and 0 mol% of Y2O3 have been prepared by chemical route using the co-precipitation method. These samples have been calcinated at 550 °C, sintered at 15000C and characterized by the Rietveld method using the X-ray diffraction data. The variation of the lattice parameter, changes in the phase composition and their microstructures are discussed. The application of the Rietveld method for quantitative phase analysis of zircon polymorphs (zircon tetragonal and cubic) reveals no formation of tetragonal phase and indicating that the matrix is the cubic phase with low concentration of monoclinic phase.

<p>Alumina-Zirconia thin films were grown on a range of substrates using dual magnetron sputtering. Film growth was achieved at a relatively low temperature of 450 °C and at higher temperatures up to 810 °C. The films were grown on well-defined surfaces such as silicon (100) but also on industrially relevant substrates such as hardmetal (WC-Co). Radio frequency power supplies were used in combination with magnetron sputtering to avoid problems with target arcing. A range of film compositions were possible by varying the power on each target. The influence of sputtering target were investigated, both ceramic oxide targets and metallic targets being used.</p><p>The phase composition of the as-deposited films was investigated by x-ray diffraction. The pure zirconia films contained the monoclinic zirconia phase, while the pure alumina films appeared either amorphous or contained the gamma-alumina phase. The composite films contained a mixture of amorphous alumina, gamma-alumina and the cubic zirconia phase. In-depth high-resolution electron microscopy studies revealed that the microstructures consisted of phase-separated alumina and zirconia nanocrystals in the case of the nanocomposites. In-situ spectroscopy was also performed to characterise the nature of the bonding within the as-deposited films.</p><p>The oxygen stoichiometry in the films was investigated as a possible reason for the stabilisation of the cubic zirconia phase in the nanocomposite. Ion beam techniques such as Rutherford backscattering scattering and electron recoil detection analysis were used in these studies. The growth of films with ceramic targets led to films that may be slightly understoichiometric in oxygen, causing the phase stabilisation. The growth of films from metallic targets necessitates oxygen rich plasmas and it is not expected that such films will be oxygen deficient.</p><p>Initial attempts were also made to characterise the mechanical properties of the new material with nanoindentation. The nanocomposite appeared to have greater resistance to wear than the pure zirconia film. In doing so, some surface interactions and some material interactions have been studied.</p> / Report code: LIU-TEK-LIC-2006:41

Alumina-Zirconia thin films were grown on a range of substrates using dual magnetron sputtering. Film growth was achieved at a relatively low temperature of 450 °C and at higher temperatures up to 810 °C. The films were grown on well-defined surfaces such as silicon (100) but also on industrially relevant substrates such as hardmetal (WC-Co). Radio frequency power supplies were used in combination with magnetron sputtering to avoid problems with target arcing. A range of film compositions were possible by varying the power on each target. The influence of sputtering target were investigated, both ceramic oxide targets and metallic targets being used. The phase composition of the as-deposited films was investigated by x-ray diffraction. The pure zirconia films contained the monoclinic zirconia phase, while the pure alumina films appeared either amorphous or contained the gamma-alumina phase. The composite films contained a mixture of amorphous alumina, gamma-alumina and the cubic zirconia phase. In-depth high-resolution electron microscopy studies revealed that the microstructures consisted of phase-separated alumina and zirconia nanocrystals in the case of the nanocomposites. In-situ spectroscopy was also performed to characterise the nature of the bonding within the as-deposited films. The oxygen stoichiometry in the films was investigated as a possible reason for the stabilisation of the cubic zirconia phase in the nanocomposite. Ion beam techniques such as Rutherford backscattering scattering and electron recoil detection analysis were used in these studies. The growth of films with ceramic targets led to films that may be slightly understoichiometric in oxygen, causing the phase stabilisation. The growth of films from metallic targets necessitates oxygen rich plasmas and it is not expected that such films will be oxygen deficient. Initial attempts were also made to characterise the mechanical properties of the new material with nanoindentation. The nanocomposite appeared to have greater resistance to wear than the pure zirconia film. In doing so, some surface interactions and some material interactions have been studied. / Report code: LIU-TEK-LIC-2006:41

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-11-06T13:51:15Z No. of bitstreams: 1 arthurchavessimoes.pdf: 3001799 bytes, checksum: a2f4926991dd99102df0b0e14c168d37 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-11-09T14:22:05Z (GMT) No. of bitstreams: 1 arthurchavessimoes.pdf: 3001799 bytes, checksum: a2f4926991dd99102df0b0e14c168d37 (MD5) / Made available in DSpace on 2017-11-09T14:22:05Z (GMT). No. of bitstreams: 1 arthurchavessimoes.pdf: 3001799 bytes, checksum: a2f4926991dd99102df0b0e14c168d37 (MD5) Previous issue date: 2017-08 / O presente trabalho teve como objetivo, avaliar a influência do tempo de condicionamento com ácido fluorídrico nas concentrações de 5% e 10%, sobre a resistência de união entre uma cerâmica Y-TZP vitrificada e um cimento resinoso. Blocos pré-sinterizados de cerâmica Y-TZP (IPS e.max® ZirCAD – Ivoclar Vivadent) foram cortados para obtenção de 70 blocos, sendo que cada pastilha recebereu dois corpos de prova. Previamente à sinterização, os blocos foram regularizados com lixas d’água de granulação #180, #600 e #1200. Eles foram então divididos aleatoriamente em sete grupos, sendo um o grupo controle no qual foi realizada a silicatização com Rocatec Soft e um grupo no qual os blocos receberam uma camada de glaze spray Vita Akzent Plus, e foram condicionada com o ácido fluorídrico (Condac Porcelana) por 5, 10 ou 20 segundos na superfície destinada à adesão. Para cimentação foi utilizado o agente de união Relyx Ceramic Primer e um cimento resinoso dual (Relyx ARC). Em cada bloco foram obtidas duas colunas de cimento, totalizando 20 amostras por grupo. Após 5000 ciclos de termociclagem, o teste de cisalhamento foi realizado (EMIC, DL 2000), a resistência de união foi registrada e utilizada para cálculo da resistência adesiva. Além disso, a análise de falha também foi realizada em todas as amostras com um estereomicroscópio (Stemi 2000-C), revelando 100% de falhas adesivas. Para avaliar a influência do tratamento de superfície na resistência de união, os dados obtidos neste estudo foram submetidos ao modelo estatístico da análise de variância (Kruskal-Wallis), após ser considerada a distribuição dos resíduos, foi determinado que os dados originais não propiciaram um adequado ajuste, pois os dados não se ajustam a uma distribuição normal de probabilidade. O teste Kruskal-Wallis revelou que houve um efeito de interação significativa, o que indica que houve alteração da resistência de união em razão do tratamento de superfície (p valor=0,001). / The objective of the present study was to evaluate the influence of the conditioning time with 5% and 10% hydrofluoric acid on the bond strength between a vitrified Y-TZP ceramic and a resin cement. Pre-sintered ceramic blocks Y-TZP (IPS e.max® ZirCAD - Ivoclar Vivadent) were cut to obtain 70 blocks, with each insert received two samples. Prior to sintering, the blocks were regularized with grit silicon carbide papers #180, #600 and #1200. They were then divided randomly into seven groups, one being the control group in which the silicatization was performed with Rocatec Soft and a group in which the blocks received a layer of Vita Akzent Plus glaze spray, and were conditioned with hydrofluoric acid (Condac Porcelana) at a concentration of 5% and 10% for 5, 10 or 20 seconds on the adhesion surface. For cementation, Relyx Ceramic Primer and a dual resin cement (Relyx ARC) were used. In each block two cement columns were obtained, totaling 20 samples per group. After 5000 cycles of thermocycling, the shear test was performed (EMIC, DL 2000), bond strength was recorded and used to calculate the adhesive strength. In addition, failure analysis was also performed on all samples with a stereomicroscope (Stemi 2000-C), revealing 100% adhesive failures. In order to evaluate the influence of the surface treatment on the bond strength, the data obtained in this study were submitted to the statistical analysis of variance (Kruskal-Wallis test), after considering the distribution of residues, it was determined that the original data did not provide an adequate adjustment because the data did not fit a normal probability distribution. The Kruskal-Wallis test revealed that there was significant interaction effect, indicating that there was change in bond strength due to surface treatment (p value = 0.001).

No description available.