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High-frequency measurements of wind, and temperature were made during the dry season of 2008 to study the development of an internal boundary layer at the main Brazilian space launching centre, Centro de Lançamento de Alcântara at Alcântara, Maranhão, Brazil. Turbulence measurements taken at the coast, in two different points 227 m apart show different daily cycles of turbulent kinetic energy friction velocity (u *), and buoyancy flux w' T ν '. Surface roughness change, surface heating change, and a gap in the natural vegetation seem to be the causes for the variation in these turbulent parameters. The mean wind cycle also shows distinct patterns. It seems that, first, internal boundary layers develop when the oceanic surface layer reaches the continent, and a second when the first internal boundary layer's flow encounters the gap. A direct implication is that turbulence is not horizontally homogeneous and measurements taken at single places are not spatially representative. Knowing how turbulence varies spatially is necessary information to understand the diffusion of pollutants exhausted by rockets near the coast.

The objective of this work was the development of Al2O3-ZrO2 ceramic composites using recycled-source of ZrO2(Y2O3). Al2O3 powder was mixed with different proportions of ZrO2(Y2O3) arising from pre-sintered blocks used in dental prostheses manufacturing. The mixtures containing 3wt% to 15wt% ZrO2(Y2O3) were uniaxially pressed at 80MPa and sintered at 1600°C-2h. Raw materials and sintered samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), relative density, hardness and fracture toughness. The results of X-ray diffraction showed α-Al2O3 and tetragonal-ZrO2 as crystalline phases after sintering. Furthermore, the relative density in all compositions was higher than 95%. The samples presented Vickers hardness and fracture toughness higher than 1300HV and 3.5MPa. m1/2, respectively.

The yttria stabilized zirconia, ZrO2 (Y2O3) has been widely used in dental prosthesis manufactured by CAD/CAM technique. This material is developed in the form of pre-sintered blocks, which are machined by extracting various customized prosthesis and generating a loss of about 30% of material. ZrO2(Y2O3) is notably a toughening for other ceramics, and has a high cost, so reusing discards these applications less noble, is strategically interesting. In this work the proposal is to recover discharges of ZrO2 (Y2O3) arising from prosthetic laboratories, reprocess them in order to reduce the particles size and subsequently sintering, demonstrating the potential use in applications less noble in dentistry. Discharges Residual of ZrO2-(Y2O3) were fragmented and then sieved to particle size separation. Powders of smaller than 63 μm were uniaxially pressed at different pressures. The compacts were characterized by the relative density showing green density of the order of 40%. After characterization, compacts were sintered at 1550°C-2h. The sintered material was characterized as its relative density and crystalline phases.

This work developed a ceramic material for dental application, spinel-base (MgAl2O4), a ceramic material with recognized translucency. Spinel powders were uniaxially pressed at 100 MPa and pre-sintered in order to obtain porous ceramic blocks. The pre-sintered blocks were characterized and indicated 80% of relative density. X-ray diffraction (XRD) only showed MgAl2O4 phase. Samples with 15 x 15 x 1 mm were submitted to infiltration using glass rich in lanthanum (La). The products were characterized by scanning electron microscopy (SEM) and mechanical properties, as hardness and fracture toughness. Results were compared to the commercial product VITA-InCeram Spinell. Relative densities exceeding 92%, hardness around 900 HV and high toughness 2.5 MPa.m1/2 were obtained for both examined systems.