Study on the Electrolysis Expansion of Carbon Cathode in [K_3AlF_6/Na_3AlF_6]-AlF_3-Al_2O_3 Low Temperature melts

摘要

Electrolysis expansion of carbon cathodes due to alkali metal penetration in [K_3AlF_6/Na_3AlF_6]-AlF_3-Al_2O_3 melts was tested. Effect of ampere density and superheating temperature on the electrolysis expansion was studied. A mathematical model was got to numerically describe electrolysis expansion performance of carbon cathode. The results indicated that K and Na penetrate into carbon cathode from outside to inside. Ampere density and superheating temperature had a great effect on the electrolysis expansion of carbon cathode. With the superheating temperature increasing from 10℃ to 50℃, electrolysis expansion increased from 1.41% to 2.10% gradually. With the ampere density increasing, the increase trend of electrolysis expansion was not linear. When ampere density was lower than 0.4A / cm~2 and greater than 0.7A / cm~2, cathode electrolysis expansion obviously increased with the increase of ampere density. Meanwhile, cathode electrolysis expansion tended to be constant as the ampere density changed at the range of 0.4A / cm~2 to 0.7A / cm~2.The results of the mathematical model in this study had a good agreement with the test results. This model would be helpful to accurately describe the anti-penetration performance of K and Na on the carbon cathode.