Experimental Study on the Adhesion Characteristics for AgSnO2 Contacts of a Relay

In order to evaluate the electrical contact performances of contact materials in relays, a new type of electrical contact simulation test system was designed and developed, in which contact materials of dynamic and static contacts can easily be replaced. The electrical contact characteristics of AgSnO2 with regard to the physical phenomenon of material surface adhesion was analyzed. Contact adhesion is divided into cold adhesion and hot adhesion. Cold adhesion occurs under the condition that no current passes the contact pair. This article mainly studies the hot adhesion phenomenon under the condition of resistive load current. The failure process of the contact pair due to dynamic welding of the contact during the experiment was analyzed. Firstly, the experimental process of hot adhesion was researched through the testing system, and then the relationship between the adhesion force and the contact resistance under adhesion condition is analyzed theoretically. Secondly, observing the microscopic morphology of the contact surface, and experimental data of other electrical performance degradation parameters in the experiment, the physical degradation mechanism of the adhesion characteristics was analyzed. Finally, the influencing factors of adhesion characteristics were explored through experiments, and the relationship between contact force, load conditions and adhesion characteristics were discussed.