Blindagem balÃstica de compÃsito polimÃrico contra o vandalismo e proteÃÃo UV para cadeias de isoladores de vidro em linhas de transmissÃo

AUTOR(ES)

Juliana de Almeida Yanaguizawa de Carvalho

DATA DE PUBLICAÇÃO

2008

RESUMO

The aim of this study was to induce the UV absorption of soda-lime silica glasses by gamma irradiation, as well as to select and evaluate the mechanical and electrical properties and also the microstructure of the polycarbonate (PC), with and without heat treatment, and the glass fiber reinforced epoxy composite, to make a prototype for transmission lines composed by a chain of glass insulators, which block the solar UV, and ballistic armor to protect the glass part from the vandalism actions. The soda-lime silica glasses were irradiated by radiation from 60Co source with different doses. As a result, irradiated samples presented a substantial absorption of UV rays as a function of dose and the cut-off changed from 295 nm to above of 600 nm. However, an abrupt change of UV absorption was observed in samples irradiated with dose above 10 kGy after couple of days of fading. The high voltage testing to evaluate the electrical breakdown voltage in a chain with sixteen glass insulators, with nine broken units - adopted as minimum insulation condition to safe maintenance - showed that the use of PC armor in the chain did not affect the insulation performance. Furthermore, an uniform distribution of good insulators along of the chain was responsible for the higher electrical breakdown voltage values. Tension, Charpy impact and microhardness testings were employed to evaluate the mechanical properties of the PC and glass fiber-epoxy composite samples. From thermogravimetry, there was no evidence of mass loss up to 300ÂC for the PC and for the composite materials. A linear correlation was obtained between glass transition temperature and dielectric strength values. However, after the heat treatment of the PC at 180ÂC in a furnace, which corresponds to a temperature above the glass transition temperature, many bubbles were formed in the PC samples. The electrical, microhardness and Charpy impact testings of PC samples with bubbles exhibited, respectively, lower dielectric strength, higher hardness and lower impact energy, indicating a fragile behavior when compared to as received PC. Previous to ballistic testing, an impact testing equipment was specially developed to evaluate the impact strength of glass insulators and ballistic armors. From the ballistic testing with various projectiles types and guns, the glass fiber reinforced epoxy composite of 10 mm in thickness protected all the glass insulators in the chain; such performance was not obtained with the PC material of 12 mm in thickness

ASSUNTO(S)

linhas de transmissÃo policarbonato vandalismo glass insulator polycarbonate compÃsito epÃxi-vidro engenharia nuclear damage isolador de vidro transmission lines ensaio balÃstico ballistic glass fiber reinforced epoxy composite degradaÃÃo

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