Synthesis and testing of uniform and gradient materials for inert anodes used in the electrolysis of cryolite-alumina melts

Investigations concerning the development of materials that are thermostable in highly reactive electrolytes have been performed. Five types of anodes differing in the technology of production and in the composition of the working layer have been synthesized. The greatest stability in tests performed in cryolite-alumina melts in an electrolysis cell working at a temperature of 960 +/- 2 degrees C, a current density 0.8 A/cm(2), and an electrolysis duration of 72 h is shown up by uniform and gradient metal-ceramic anodes with variable concentrations of the metallic and oxide phases prepared by hot pressing. These samples represent virtually porousless (in the second variant, layered) compositions whose working surface or the outer layer increases the resistance to the action of both atomic oxygen and electrochemical corrosion during electrolysis.