DTA and TGA Studies of Four Ag-MeO Electrical Contact Materials

The results of the differential thermal analysis (DTAt and the thermal gravimetric analysis (TGA) of four different metal oxides and their respective Ag-MeO materials indicated that the thermochemical properties of the Ag-MeO materials are directly influenced by the metal oxide components. The energies required to bring the different Ag-MeO materials into different thermal states were calculated, diseussed, and compared. This investigation postulates two hypotheses. First, the arc erosion loss of a contact material depends on the erosion mode. If the predominate mode is splattering, then the Ag-CdO material may be the superior to pure silver because it requires more heat to reach an equivalent thermal state. Second, the oxide, the function of which is to weaken the contact welding, tends to remain on the surface thus increasing the contact resistance. Cadmium, due to its low boiling point, evaporates from the surface. These unique properties may account for the superiority of Ag-CdO as a contact material over other single oxides.