Search results for: L. Centurioni
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Journal of the European Ceramic Society > 1999 > 19 > 6-7 > 781-785
Low temperature aqueous synthesis (LTAS) has been applied to the preparation of La or Nb-doped (Ba,Sr)TiO 3 powders. Doping elements have been mixed to precursors, in order to directly obtain crystalline powders with modified composition. Similar powders, doped by conventional wet ball-milling process, have been also prepared for comparison. Ceramic samples have been obtained by isothermal...
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The eight cycloaliphatic components exposed for three years to environmental aging have shown a satisfactory be haviour, since the electrical and thermal characteristics have not suffered appreciable variations. The morphological analysis has not evidenced sensible plasticization phenomena, or in general, modifications of the chemical structure. Only a change in sample colour without loss of hydrophobicity...
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The thermosetting resins are adversely affected by water sorption from humid environments. The degradation effects under temperature, humidity and stress fatigue tests have been associated with both water induced plasticization and micromechanical damages. Sorbed moisture, in fact, acting as a plasticizer and swelling agent for the resin, differently deteriorates the mechanical and chemical integrity...
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Some preliminary results of a research program aimed to the study of physical chemical and electrical effects of different types of ageing on four thermosetting resins are presented. The selected materials were submitted to: a) thermal ageing (150 °C, three months); b) environmental ageing bath using a weather-o-meter and a dry U.V. irradiation chamber. The results of tracking and fog chamber tests,...
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The preliminary results here presented indicate, for the LDPE used, in the ranges of time and voltage explored, with the specimens and electrodes geometry adopted, using steel pins, that the parameter “treeing inception voltage” increases with ageing. Moreover the shape of the “life curve” obtained for treeing inception, could be consistent with the existance of a threshold for voltages lower than...
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Electrical apparatuses for indoor use are often equipped with insulating components made by organic materials, which can be subjected to particular ambient conditions leading to a situation similar to the one experienced in outdoor conditions, but, obviously, leas severe.
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The tests results reported show that the resistance-to-tracking classification of the tested materials is comparatively correct when using either S1 or S2 metal electrodes; therefore there are no reasons to prefer one of the two stainless steels.
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IEEE Transactions on Electrical Insulation > 1977 > EI-12 > 2 > 147 - 152
IEC/TC15 is preparing a new edition of Publication 112 concerning a method for determining the comparative tracking index(CTI) of solid insulating materials under moist conditions; the Electrical Engineering Dept., University of Genoa, has performed a set of tests on this subject. A short description of the aims, of the procedure, and of the apparatus used for the tests reported in IEC Publ. 112 is...
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IEC/TC15 is preparing a new edition of Publication 112 concerning a method for determining the comparative tracking index (CTI) of solid insulating materials under moist conditions; the Electrical Engineering Dept., University of Genoa, has performed a set of tests on this subject. A short description of the aims, of the procedure and of the apparatus used for the tests reported in IEC Publ. 112 is...
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The large number of applications of epoxy resins in the electrical industry originates an increasing interest in the behavior of these materials under endurance tests. In particular, several authors have studied_the action of partial discharges on these dielectrics1–5, which, in practice, are often subjected to this kind of stress. In the present paper, the first results of a research program on the...
