Auger Electron Spectroscopy, SEM and Non-Dispersive X-Ray Analysis Techniques for Examination of Ag-CdO Contact Materials

A new examination method is described by which the contact surface microstructure and composition may be related to effects caused by electrical arcing. Auger Electron Spectroscopy (AES) and Non-Dispersive X-ray Analysis surface-study techniques are used to examine the anode surface composition of powder metallurgy Ag-CdO contact materials. The microstructure and morphology changes which take place on the anode surface as a result of electrical arcing were observed using the Scanning Electron Microscope. Technical differences between the AES technique and the Non-Dispersive X-ray method are discussed in general; specific application to Ag-CdO contact material is included, The chemicai composition of two different contact materials that were studied is the same. However, electrical tests show that one material is more susceptible to welding than the other. The results show that, for both materials, the CdO concentration on the anode surface after electrical arcing is much larger than before. The amount and distribution of CdO in the arc spot area differs between the two materials. One material shows higher concentration of CdO in the periphery of the arc spot, the other material shows higher concentration in the central region. For the same arc energy, differences exist in the quantity of CdO found in the arced area.