(“bias”) between the profiles and adjustment (“matching”) of the profiles, avoiding abrupt changes in the average profile. A real case study was conducted with determination of the trajectory of the rockets launched from the “Alcântara Launch Center” attaining a result that the point of impact strikes the dispersion field with less than 10 per cent error, relative to its radius using the settings profile.
Radar absorbing materials based on thin films processed by physical vapor deposition technique
Viviane Lilian Soethe Technological Institute of Aeronautics email@example.com;firstname.lastname@example.org
Thesis submitted for PhD degree in Physics at Technological Institute of Aeronautics, ITA, São José dos Campos, São Paulo State, Brazil, 2009.
Advisors: Dr. Mirabel Cerqueira Rezende and Dr. Evandro Luis Nohara
Keywords: RAM, Thin films, Radar absorbing materials, PVD.
Abstract: This work shows the study of the production of metal thin films, with nanometric thicknesses, by Physical Vapor Deposition (PVD). Triode magnetron sputtering, electron beam and resistive evaporation techniques were used for the deposition of Al, Ni, Ti, Cu, C, CNx and AlxFey e NixTiy alloys. These materials were deposited on polymeric substrates of poly(ethylene terephtalate), with thicknesses of around 0.1 and 0.01 mm. Characterization of the films involved different aspects, such as: thickness, composition and the electromagnetic wave attenuation behavior, in the frequency range of 8–12 GHz. The correlation of the data obtained aimed to evaluate the performance of the nanofilms as Radar Absorbing Materials (RAM). The main result may be cited as the success of the PVD technique used for metal thin film production, being much lighter than the conventional absorbers, and with an excellent RAM behavior in the microwave range. Metal nanofilms are characterized as presenting thickness values below skin depth and dielectric losses. The experimental results show also that the film’s performance in microwave attenuation is affected by different factors, such as the deposition technique used, the metal type and the film thickness. Among the results obtained, we may mention: Al films with attenuation values of 99 per cent at the frequency of 9.5 GHz, AlxFey and NixTiy films, processed by resistive evaporation technique, with attenuation values
Journal of Aerospace Technology and Management
of 70 per cent in broadband (8-12 GHz) and also multilayer structures obtained by adequate combination of nanofilms, with better RAM performance.
Synthesis, doping and characterization of furfuryl alcohol resin and phenol- furfuryl alcohol resin aimed at the optimization of glass-like carbon processing
Silvia Sizuka Oishi São Paulo State University email@example.com
Thesis submitted for Masters in Mechanical Engineering at São Paulo State University, Guaratinguetá, São Paulo State, Brazil, 2009.
Advisors: Dr. Edson Cocchieri Botelho and Dr. Mirabel Cerqueira Rezende
Keywords: Glassy-like carbon, Doping, Furfuryl
alcohol resin, Phenol-furfuryl Physicochemical properties.
Abstract: Given the growing importance of glassy carbon material in strategic areas, due to its intrinsic characteristics, such as lower density and good thermal and electrical conductivity values, several studies have been observed looking for new polymeric precursors and tighter processing parameters. Similarly, this study aims to establish synthesis routes for furfuryl and phenol-furfuryl alcohol resins and their doping with copper particles, in order to produce reticulated glassy carbon (RGC) electrodes. Within this context different formulations of furfuryl and phenol-furfuryl alcohol resins were synthesized by variation of the monomers – furfuryl alcohol, phenol and formaldehyde, respectively. Confirmation of the success of the synthesis was undertaken using FT-IR spectroscopy, gas chromatography, thermal analyses by differential scanning calorimetry (DSC) and carbon yield content measurements that present results between 27 and 45 per cent of carbon. After this, the specimens were doped with copper colloidal particles. The doped and non doped resins were catalyzed, impregnated in polyurethane (PU) foams and carbonized, in order to obtain the reticulated glassy carbon. Optical and Scanning Electron Microscopy analysis show the homogeneity of PU foams impregnation and uniform texture of RGC specimens. Compression results present the best values for RGC resulting from the carbonization with furfuryl alcohol acid resin (0.55 MPa).
V. 1, n. 2, Jul. - Dec. 2009