Preparation And Research On The Properties Of Multiform Oxides Doped Tin Dioxide Electrodes

Tin dioxide electrode is a vital part of the glass electric melting furnace. It's important to improve the properties of tin dioxide electrode to catch with the fast development of electric melting technology. Tin dioxide is an n-type semiconductor, and has the performance of enduring high temperature and corrosion resistance, it can be used to melt nearly all kinds of glass. However, nowadays the advanced Tin dioxide electrodes are still depended on import, it is urgent to improve the properties of homemade tin dioxide electrodes.So far, the studies on SnO₂ mainly focused on gas sensitive ceramics, pressure sensitive ceramics and thin films, which were exploited the electrical properties of SnO₂ ceramic. Whereas, as an electrode used in glass electric melting furnace, SnO₂ based ceramic must have good electrical properties and sintering properties. In the paper, the way to improve the two aspects would be introduced in detail.It was studied on preparation of powder, shaping way and sintering process in this paper, and a novel technique of preparing SnO₂ electrodes was elaborated too. Composite-doped SnO₂ powders were prepared by co-precipitation. The nano-scale powders would exhibit good properties on the sintering of the electrodes. Furthermore, the manufacture process was simplified because composite-doped SnO₂ was prepared directly, which would decrease the deleterious elements.In the paper, it was described the way to prepare the SnO₂ powder doped ZnO, Sb₂O₃, CeO₂ and MnO₂ respectively and mixed added. The crystal type and strength of SnO₂ were analyzed by X-ray diffraction (XRD). The results showed the average grain size was about 25 nanometers. It proved that ZnO and CeO₂ could boost SnO₂ crystallization and not change its crystal structure, while Sb₂O₃ could inhibit SnO₂ crystallization. The transmission electron microscope (TEM) results indicated that powder would be conglomerated easily when the sintering temperature rose.In the paper, the best contents of the additions as well as shaping pressure and sintering temperature was studied, and the resistivity of samples was also analyzed. Furthermore, electrical mechanism of (ZnO, Sb₂O₃, CeO₂)-doped SnO₂ based ceramic was discussed. It proved that Sb₂O₃ could improve the electrical property of SnO₂ electrodes. Mixed doped results showed the best mass ratio of Sb₂O₃ and CeO₂ was 4:1. Samples were shaped under normal pressure because of the small size. The influence on the resistivity with different shaping pressure was investigated. The results showed the best pressure was 30MPa. Throughout the experiments, sintering temperature had a remarkable effect on the resistivity. The resistivity was reduced when the temperature was rising. However, the electrical properties would be worse, because of the appearance of many liquid phases when the sintering temperature was too high.In the paper, the influence of different contents of ZnO on the sintering properties of tin dioxide electrodes was researched. By the testing of SEM, the bulk density and the electrical resistivity, the influence of ZnO addition from 0 to 10wt% on the sintering properties of SnO₂ electrodes was analyzed. The results showed that 1wt%-3wt% ZnO could boost the densification of the electrodes, and reduce the resistivity at room temperature. But when additional amount was up to 5wt%, considerable ZnSnO₃ grains would be generated, which acted as a barrier for grain mobility, inhibiting densification and grain growth. Therefore a reasonable amount of ZnO could make good properties of SnO₂ electrodes. Moreover, the influence of different contents of multiform oxides on the sintering properties of tin dioxide electrodes was studied. Through the testing, it was analyzed the influence of the different contents of ZnO, MnO₂, CeO₂, Sb₂O₃ on the sintering properties of tin dioxide electrodes. Depending on the reasonable sintering technique, the bulk density of samples could achieve to 95% of theoretical density. It's found that ZnO, MnO₂, CeO₂ and Sb₂O₃ could not only reduce clearly the resistivity of SnO₂ electrodes at room temperature, but also increase the bulk density. Compared to homemade ones, the bulk density, Vickers hardness and toughness of the electrodes could be improved by 3.1%, 13.9% and 17.0% respectively.