Single-crystal zirconium carbide as a high-temperature thermionic cathode material

Experiments to determine the feasibility of using transition metal carbides as stable thermionic cathodes at temperatures exceeding 2000 K are discussed. The primary emphasis here is electron emission and thermal stability properties of single crystals of ZrC. To obtain accurate emission versus temperature data, the spectral emissivity at 0.65 mu m of single-crystal ZrC specimens was measured in the temperature range 1200>