Papers by Keyword: Al₂O₃-SiC Composites

Abstract: The mechanical properties of Al₂O₃-SiC based composites were improved by the addition of ZrO₂(3Y) particles in the range of 10 to 25 vol.%. Al₂O₃-SiC/ZrO₂(3Y) composites were manufactured by pressureless sintering at 1550, 1600, and 1650^oC. Sintered composites were characterized for density, XRD, microstructure and mechanical properties such as flexural strength, fracture toughness and hardness. The results showed that the highest flexural strength of 250 MPa was obtained with 25 vol.% ZrO₂(3Y) composite sintered at 1600^oC due to higher density and smaller Al₂O₃ grains in comparison with samples sintered at 1550^oC and 1650^oC, respectively. The maximum fracture toughness of 5.66 MPa.m^1/2 was obtained with 20 vol.% ZrO₂(3Y) sintered at 1600^oC. The highest hardness of 9.16 GPa was obtained with composite of 10 vol.% ZrO₂(3Y) sintered at 1600^oC as it contains the largest amount of hard SiC.

Abstract: Increased processing pressure has resulted in need for the industry to optimize mechanical properties of ceramic foam filters used for molten metal processing. This paper will summarize the effect of ceramic slurry formulation on mechanical properties of reticulated porous ceramics processed by replica method. Commercial polyurethane sponge materials were chosen as a template to produce the RPC (reticulated porous ceramic) from a shear thinning multi component aqueous slurry composed of alumina, SiC, colloidal silica and some different additives. Thermal transformation sequence of the mixtures, resultant macrostructure and microstructure, relative density, grain morphology, phase composition, and mechanical strength of the sintered porous ceramics were investigated. Mechanical properties of struts were investigated by a theoretical model. The RPC had its maximum strength when Alumina/SiC weight ratio was 4.4. Such materials sintered at 1650° C in air, due to their excellent functional properties, are suitable for application as molten metal filter.