| Conductive ceramics made from several of metalloid oxides were prepared through conventional technique of ceramic preparation, and they were mixed with silver powders to form electrical composite materials. Fundamental physical and chemical characteristics of ceramics and the composite materials were discussed. Experiment results indicate that electrical contact materials have fine mechanical propertieies and steady electrical characteristics. Ag/Conductive ceramics contact materials can be used as a substitute to Ag/CdO.The proportion of Ni and La in the structural formula and the sintering technics were changed to discuss their effect on the electrical resistivity and seek the optimal sintering temperature and proportion. Conductive ceramics and other metal or metal-oxide which acted as the third phase were mixed into silver powders in different proportions to discuss the effect on the mechanical, electrical and calorific characteristics of the contact materials.By means of XRD and SEM, we studied the phase structure and the microstructure of the ceramics and studied the connection of microstructure and macroscopical characteristics.The conductive ceramics have particular microstructure of network distribution and samdwich. With high melting point and low resistivity, they are actually a kind of semiconductor material with perfect conductivity. The electrical contact materials have low resistivity, fine mechanical characteristic, nice corrosion-resisting performance and obvious chemical stability. All the above-mentioned performances make this kind of contact materials satisfy various demands in electrical contact fields.To find a logical technologic parameter, the study on the technique of powder blending was taken. The powders were ball milled for different time respectively and then annealed at 700℃. The composite contact materials are well-proportioned after milled 2 hours. The grain size reach minimum basically. After annealed at 700℃, the... |
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