ABSTRACT: The optical solar reflector is basically a mirror of second surface with low absorptivity/emissivity ratio and negligible degradation in the space environment, which makes it an excellent coating for thermal control of satellites. It works as a radiator and is used in particular parts of the external surfaces of the satellites in order to reject the undesirable heat to the deep space. In the Brazilian Space Programs, the radiators of the satellites are generally painted with special white paints in order to reject heat instead of the use of optical solar reflector. The problem of white-ink radiators is the high degradation of the thermo-optical properties that happen over the useful lives. Thus, a process of manufacturing and assembly of optical solar reflector was developed in Brazil. To validate this process in terms of mechanical and thermal properties, 3 types of optical solar reflector radiators were manufactured, and their absorptivity and emissivity properties at the temperature of 23 ºC were measured. Optical solar reflector coupons were mounted on aluminum plates to perform vibration, thermal vacuum and thermal-shock tests. A study was also done to optimize the thickness of the glue to fix the structure of the satellite on the optical solar reflector. It showed an excellent environmental stability and maintained its thermo-optical characteristics after the tests.

Boron doped ultrananocrystalline diamond (BDUND) films were grown and characterized on porous silicon (PS) substrates. PS samples were prepared from n-type monocrystalline silicon wafers (100) with 1-20 Ω.cm of resistivity, by electrochemical etching, using HF-acetonitrile solution as electrolyte. BDUND films were grown by Hot Filament Chemical Vapor Deposition using CH4, H2 and Ar. The doping process consisted of an additional hydrogen line, passing through a bubbler containing B2O3 dissolved in methanol, with boron/carbon ratio of 20000 ppm in solution. Raman spectroscopy and X-Ray diffraction were used to evaluate the quality of the films. Scanning electron microscopy was used for morphological characterization, and confirmed that the films covered the pores without filling them. Electrochemical response and capacitance behavior of the electrodes were explored, by cyclic voltammetry. Samples presented high capacitance, confirming that BDUND/PS electrodes are promising for application as electrochemical capacitors.

SAE 1020 construction steel is widely used as mortar reinforcement and small machine parts, but aside good surface properties as high ductility, hardness and wear resistance, its surface is prone to severe corrosion. As it is known, Chromium in amount over 12%-13% in the Fe alloys renders them resistance to several corrosive attacks. SAE 1020 samples were recovered with Chromium film and then bombarded either by nitrogen Ion Beam (IB) or Plasma Immersion Ion Implantation (PIII) to recoil implant Cr atoms in the Fe matrix. Samples treated by 100 keV N+ IB showed irregular, thin Cr profile, remaining a part of the film on the surface, to about 10 nm. Samples treated by 40 kV N PIII presented Cr layer of about 18% at., ranging to around 90 nm. Cr of the film was implanted in the Fe matrix in an almost flat profile. Results of corrosion test showed good performance of the PIII treated sample. The IB treated sample showed some enhancement over the non-treated reference and the only Cr film deposited sample showed no modification on the corrosion behavior as compared to the non-treated reference sample.