Vaporization of carbon from Cu-WC contact during arc discharge in vacuum

To identify the components emitted from tungsten carbide (WC) base contact during arc discharge in vacuum, spectroscopic measurements were performed for vacuum arc discharges between Cu, W, C, WC, and Cu-WC contacts. As a result, spectra of C and W which have extremely low vapor pressures were observed as well as that of Cu. To obtain the conclusive evidence of the vaporization of C, W, and Cu, the deposits on the contact holders were also investigated by means of surface analysis methods such as Auger electron spectrometer and X-ray photo-electron spectrometer. The mechanism of simultaneous vaporization of those components with different vapor pressures was discussed by means of thermal analysis. It shows that the superheating of WC at the contact surface could cause the vaporization of carbon.