Quantitative investigation of material erosion caused by high-pressure discharges in air and nitrogen

Single-spark erosion experiments were conducted in different pure metal samples. The samples were used as the cathode, and a platinum electrode was used as the anode. The sparks were produced at high pressure and room temperature, having at this conditions a breakdown phase (ca. 100 ns) and an arc phase (several hundreds of mus). The crater volumes on the different materials were correlated with several properties of materials, in view of different models of material erosion related to melting enthalpy, vaporization enthalpy and sublimation energy. It was found that the quotient between the eroded volume and the spark energy correlates well with a function of the energy necessary to heat the material up to the melting point and to melt it. The particle ejection model can be used to explain this process. Moreover, it was found that the crater shape is related to the surface tension of the molten material. These investigations may be relevant for the development of high-performance materials for electrode and contact applications.