Preparation and enhanced mechanical properties of novel Al 2 O 3 ‐C ceramic filter reinforced by microporous powder and SiC whiskers

Abstract In present work, the novel Al 2 O 3 ‐C ceramic filter fabricated by using microporous corundum‐spinel powder instead of dense Al 2 O 3 powder and reinforced by SiC whiskers is proposed. The effects of Si powder content (0, 3, 6, and 9 wt. %) on the microstructures and mechanical properties of the filters were studied. After replacing the α‐Al 2 O 3 micro‐powder with microporous corundum‐spinel powder, the in situ spinel whiskers were formed inside the filter skeleton under the reducing atmosphere. The rough surface structure of the microporous powder increased the interface contact area with the small‐sized carbon particles, resulting in a compact interface bonding in the filter skeleton and a higher cold compressive strength of the filter. When the Si powder content increased to 6–9 wt. %, the in‐situ SiC whiskers were formed not only between the microporous powder, but also inside the pores near the surface of it by vapor‐solid reaction mechanism in the filter skeleton. The SiC whiskers synergized with the microporous powder to form a more compact interface structure, thus remarkably enhancing their cold compressive strength and thermal shock resistance. Overall, the mechanical properties of the filters were significantly improved by the addition of 9 wt. % Si powder. The filter skeleton had an apparent porosity of 36.2% and a bulk density of 1.93 g/cm 3 . The filter also exhibited a high cold compressive strength of 1.59 MPa and a superior thermal shock resistance. It has the potential for better purification efficiency on molten steel in the future due to a rougher skeleton surface structure compared to existing Al 2 O 3 ‐C filters.