Microstructure and Properties of Porous Silicon Carbide Ceramic Modified with Molten Salts

The porous silicon carbide ceramics were surface modified with molten salts of anhydrous aluminum sulfate and sodium sulfate and the phase composition and microstructure after molten salt reaction were studied. The PM2.5 filtering performance of the porous silicon carbide ceramics before and after modification was tested. The results show that the acicular mullite whiskers with lengths of over ten microns and diameters of several hundred nanometers were produced by the reaction of the molten salts of aluminum sulfate and sodium sulfate with silicon carbide at 900 ℃. The mass concentration of PM2.5 in diesel smoke was decreased from over 280 μg·m-3 to less than 150 μg·m-3 after filtration by the molten salt modified porous silicon carbide ceramic, which was better than that by the unmodified porous silicon carbide ceramic (200 μg·m-3). The mullite whiskers can block the movement of the particulate matters in diesel smoke and make them precipitate between whiskers, resulting in the improvement of smoke filtering performance of the porous silicon carbide ceramics.