Tailoring of the electrical properties of silicon carbide for field grading application

This paper reports on the results of a numerical modeling that considers the field grading phenomena of SiC powder with a variable resistivity dependent on particle size. The particle shape and size of commercially available SiC powders were altered by ball milling. In an earlier work, we have determined the electrical properties of various SiC powders by using a controlled-pressure Ohmmeter. Different pressures were applied to improve the particle-to-particle contacts. The highvoltage resistivity measurements were done by ramping a DC voltage at a rate of 5 V/s up to 2500 V and monitoring the current. Milling of the original powder for 30 minutes was performed, resulting in a decrease of the average particle size from 50.6 μm to 2.06 μm (median of the volume distribution). This led to a resistivity increase from 0.38 to 52 MΩ.cm under an applied pressure of 21 MPa. All materials have shown non-linear electrical behavior.