Preparation And Scientific Research Of Low-Resistivity And High-Density Tin Dioxide Ceramic

Tin dioxide ceramic is an important part in the glass electric melting furnace. We need to improve the performance of tin dioxide ceramic with the fast development of electric melting technology. Tin dioxide is an "n" type semiconductor, and has the performance of enduring high temperature, corrode-resistance, good conductance; it could be used as electrode for melting nearly all kinds of glass. However, nowadays the high quality Tin oxide ceramic still depended on imports, it is urgent to improve the performance of home-made ceramic.In the past, the studies about SnO₂ mainly focused on capacitor ceramic, gas sensitivity ceramic films of SnO₂, which founded the good theoretical foundation for preparation of SnO₂ based ceramic. Whereas, as an electrode used for glass electric melting furnace, SnO₂ based ceramic must have good Electrical properties and sintering properties, in the paper, the ways how to improve the two aspects would be introduced in detailed.In this paper, a new technique for preparation of SnO₂ ceramic was elaborated. Composite-doped SnO₂ was prepared by co-deposition reaction. The nano-size powder exhibits good performance on the sintering of the ceramic. Furthermore, the manufacture process was simplified because composite-doped SnO₂ was prepared directly, which would decrease the deleterious elements.It was studied on preparation of powder, forming process and sintering process in this paper. Firstly, base on the traditional process and related studies, Ce, as a new addition, was doped into the powder. The experiment results showed that the electrical properties and sintering properties of ceramic were improved by CeO₂ doped SnO₂. In the section two, we described that the way to prepare the SnO₂ powder singly doped Sb, Ce, Cu and Mn and mixed doped. The crystal type and strength of SnO₂ were analyzed by X-ray diffraction (XRD) and TEM, the results showed the average crystal size was about 35 nanometers. The Sb and Ce additives could boost SnO₂ crystallization but not change its crystal structure. The transmission electron microscope (TEM) results indicated that powder would be conglomerated easily when the heat treating temperature was rising.Above powders were used for preparing SnO₂ based ceramic. In the section three, the process that best contents of the additions as well as forming pressure and sintering temperature was studied, and the resistivity of samples was also analyzed. Furthermore, electrical mechanism of (Sb, Ce)-doped SnO₂ based ceramic were discussed. The results showed the best mass ratio of them is 2:1 (Sb₂O₃:CeO₂). Samples were shaped on normal pressure because of the small size. The influence on the resistivity with different forming pressures was investigated; the results showed the best pressure was 30Mpa. Through the experiments, firing temperature had a remarkable effect on the resistivity, the resistivity was decreasing with the temperature rising. However, the electrical properties would be worse when the firing temperature was too high, because of the appearance of many liquid phases.High performance tin dioxide ceramic would exhibit good electrical properties, sintering performance and mechanics performance. In the section four, reasonable sintering techniques via many experiments were studied. Through the testing of Scanning electron microscopy (SEM), the results made it clear that the influence on the densification of samples with different additive, shaping pressure and firing time, so a rational firing technique was found. The density of samples could reach by 96% of theoretical density. The experiment results showed that Ce can improve the performance of SnO₂ ceramic. When lwt% Ce-doped SnO₂ based ceramic, the density, Vickers hardness and toughness will be respetively improved 5.4%, 10.7% and 13% contrast to Ce-free one.