SWITCHING BEHAVIOUR AND CHANGES IN MICROSTRUCTURES OF SILVER-METAL OXIDE CONTACT MATERIALS

摘要

The switching behaviour of contact materials -i.e. in a contactor- depends not only on material properties it also varies for different utilization categories. For powder metallurgically produced AgCdO12 and AgSnO_2 12 the progress of erosion as well as changes of arc mobility and of over temperature have been observed in the course of AC1, AC3, and AC4 life tests, respectively. These phenomena are mainly determined by the condition of the contact surface and of surface near zones. Therefore metallographic micro sections and surfaces of contacts have been thoroughly investigated after the end of the life tests. Characteristic modifications in microstructure and surface topology are described and related to the switching behaviour of the two materials.