Microstructure control to reduce leakage current of medium and high voltage ceramic varistors based on doped ZnO |
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| Affiliation: | 1. Université Toulouse, UMR CNRS-UPS-INP 5085, 118 Route de Narbonne, 31062 Toulouse Cedex 9, France;2. TRIDELTA Parafoudres S.A., Boulevard de l’Adour, 65200 Bagnères de Bigorre, France;1. Dnepropetrovsk National University, Dnepropetrovsk 49010, Ukraine;2. Universidad Tecnologica de la Mixteca, Huajuapan de Leon, Oaxaca 69000, Mexico;3. South China University of Technology, Guangzhou 510640, China;1. CRISMAT Laboratory, UMR 6508 CNRS-ENSICAEN 6, Boulevard du Maréchal Juin, 14050 Caen Cedex 4, France;2. LMCPA Laboratory, Université de Valenciennes et du Hainaut-Cambrésis, ZI du Champ de l’Abbesse, 59600 Maubeuge, France;3. Microwave Processing and Engineering Centre, The Pennsylvania State University, 107 MRL, University Park, PA, USA;1. CIRIMAT UMR CNRS 5085, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 9, France;2. LAPLACE, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 9, France;3. TRIDELTA Parafoudres S.A., Boulevard de l’Adour, 65202 Bagnères de Bigorre Cedex, France;1. High Voltage Laboratory of the Federal University of Itajubá, 37,500-903, Bairro Pinheirinho, Itajubá, Brazil;2. Physics and Chemistry Institute of the Federal University of Itajubá, Av BPS n, 37,500-903, Bairro Pinheirinho, Itajubá, Brazil;1. PPG-CEM, Federal University of São Carlos, São Carlos, Brazil;2. Federal University of São Carlos, Department of Materials Engineering, Rod. Washington Luiz, km 235, São Carlos 13565-905, SP, Brazil |
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| Abstract: | ![]()
The leakage current (If) and the non-linearity coefficient (α) are crucial parameters in varistors. This work, deals with the optimization of the electrical characteristics of medium and high voltage varistors based on the ZnO–Bi2O3–Sb2O3 system. First, the aim was to allow the formation and the stabilization of the spinel phase by reducing the heating rate. To do so, the right sintering temperature and dwell time have to be chosen to obtain a breakdown field suitable for industrial requirements. During cooling, the spinel phase can return to a pyrochlore phase, which contributes to the increase of leakage current. In a second part, this reaction was prevented by faster cooling in an appropriate temperature range. The fine-tuning of both the heating and cooling phases leads to a significant decrease of the leakage current. Moreover, the value of the non-linearity coefficient was increased by 80%, due to better and more homogeneous wetting of the ZnO grains by the Bi-rich phase. |
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| Keywords: | Leakage current Microstructure Pyrochlore Varistor Zinc oxide |
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