Effects of In-Situ-Formed 9Al(2)O(3)center dot 2B(2)O(3) on the Corrosion Resistance of Al2O3-Based Porous Ceramic in Molten Aluminum

摘要

White fused alumina (WFA), alpha-Al2O3 powder, aluminum hydroxide powder and pseudoboehmite powder (PB) are each mixed with boric acid according to the stoichiometric ratio of 9A1(2)O(3)center dot 2B(2)O(3) in order to study the formation process. For the corrosion experiment, A1(2)O(3)-based porous ceramic with and without the addition of boric acid is prepared and soaked in molten aluminum for 48 hat 870 degrees C. The results show that the synthesis temperature of 9Al(2)O(3)center dot 2B(2)O(3) is 1000 degrees C, except for the mixture of PB and boric acid for which the synthesis temperature is 900 degrees C. The corrosion resistance of the samples with the addition of boric acid in molten aluminum is improved because of the generation of 9Al(2)O(3)center dot 2B(2)O(3) around the pores.