文摘
The over-current protector is one of the main applications of the positive temperature coefficient (PTC) thermistor. Low room-temperature resistance and a PTC effect are required for the use of the over-current protection. As a result, lowering the room-temperature resistivity of PTC materials becomes very important. From a Japanese patent, the method of adding metal to -based PTC ceramics to form composites has shown good results. But in recent publications, few papers were related to this area. Furthermore, in the limited literature, the resistance–temperature curve of the material expressed a negative temperature coefficient (NTC) effect when metal was present. In the present work, chromium (Cr), was added to ( ceramics to form PTC composite with higher Curie temperature . Under a given composition and method, the prepared composite had low room-temperature resistivity and PTC effect . From the experimental results obtained, a structural model of the composite is proposed. The co-function of metal and ceramics, and sintering atmosphere factor on the PTC effect are discussed in this model. By employing this model, the resistance–temperature properties of the composites can be explained satisfactorily.
