Study On The Property And Process Of Low Voltage ZnO Varistors

The property and process of low-voltage ZnO varistor were studied in this dissertation The section of specimen was observed by SEM and the distribution of some kinds of element was be analyzed. The effect of some element to the property of ZnO varistor was researched by theory. The process of sinter and heat treatment was designed according to phase diagram and concerned model was constructed by which the distribution of the element-doped in specimen and the characteristic of V1mA-T can be analyzed.The relationship between granularity and performance was given by using probability method.Experimentation show that electric performances of low-voltage ZnO varistor can be improved by using chemical coprecipitation powder, inner stress of it can be released and good uniformity of ceramic can be obtained by using TiO2-sel. The function of Nb2O5 was discovered too. The phase transformation of Bi2O3 is the important source of an inner stress of ZnO varistor by researching the crystal lattice, and according to the ZnO-TiO2 phase diagram proper cooling rate between 850℃to 700℃was good at the improvement of performance, which was be proved by contrast test.In this research, the performance of specimen, preparation of which by several kinds of process, was tested and last summery is good ZnO varistor can be made by using composite process.