PHYSICAL AND STRENGTH PROPERTIES OF POROUS ALUMINA PRODUCED BY SLURRY BOILING WITH DIFFERENT SOLIDS LOADINGS
Keywords:
Porous alumina, Direct foaming, Slurry boiling, Solids loadingAbstract
The effect of slurry solids loading on the sintered properties of a 94% alumina foam was studied. Slurries with solids content of 30 to 45 wt% were prepared. The porous samples were fabricated using a direct foaming method by boiling the slurries until the alcohol was evaporated. Sintering of the porous alumina was conducted at 1,600 ºC for 2 h. The final properties of porous alumina were investigated. It was found that the samples had similar values of apparent density from 3.55 to 3.57 g/cm3, regardless of solids loading. The apparent densities were similar because the closed pore volumes were also similar. The bulk density (1.73 g/cm3) and the porosity (52%) of samples made from slurries with solids content 30 to 40 wt% were also similar. However, the increase of solids loading to 45 wt% decreased the bulk density to 1.47 g/cm3 and increased the porosity to 59%. This was due to an increase of the open pore volume. The SEM analysis found that the 45 wt% sample had numerous small open pores, not only within the cell structure of the foam, but also in the cell walls. The flexural strengths decreased slightly from 5.5 to 4.7 MPa with increased solids loading. The results showed that the slurry solids loadings offered some control over the foam properties and that the slurry boiling method was capable of producing porous alumina with comparable properties to ceramic foams made by other methods.
References
ASTM, C. (2006). Standard test method for water absorption, bulk density, apparent porosity, and apparent specific gravity of fired whiteware products. West Conshohocken, Pennsylvania, US: ASTM International., C373-88.
Chen, Y., Liu, G., Gu, Q., Li, S., Fan, B., Zhang, R., and Li, H. (2019). Preparation of corundum-mullite refractories with lightweight, high strength and high thermal shock resistance. Materialia., (8):100,517.
Cooymans, J., Smolders, C., and Luyten, J., Inventors, Vlaamse Instelling Voor Technologish, Assignee. August 7, 2003. Ceramic composite foams with high mechanical strength. U.S. Patent Application No., 10:182,322.
Gain, A.K., Song, H.Y., and Lee, B.T. (2006). Microstructure and mechanical properties of porous yttria stabilized zirconia ceramic using poly methyl methacrylate powder. Scripta Mater., 54(12):2,081-2,085.
Hammel, E.C., Ighodaro, O.R., and Okoli, O.I. (2014). Processing and properties of advanced porous ceramics: An application based review. Ceram. Int. 40(10):15,351-15,370.
Li, F., Kang, Z., Huang, X., Wang, X.G., and Zhang, G.J. (2014). Preparation of zirconium carbide foam by direct foaming method. J. Eur. Ceram. Soc., 34(15):3,513-3,520.
Peng, H.X., Fan, Z., Evans, J. R. G., and Busfield, J. J. C. (2000). Microstructure of ceramic foams. J. Eur. Ceram. Soc., 20(7):807-813.
Rahman, H.A., and Guan, Y.C. (2007). Preparation of ceramic foam by simple casting process. In International Conference on Engineering and Environment, p. 10-11.
Şan, O., Koç, M., and Cengizler, H. (2019). Production of porous ceramic from clinoptilolite incorporating aluminum powder. Ceram. Int., 45(18):24,037-24,043.
Sarkar, D. (2019). Ceramic Processing: Industrial Practices. CRC Press.
Somton, K., Rodchom, M., Laoratanakul, P., and McCuiston, R.C. (2018). Porous Alumina Processing Using the Direct Foaming Technique Based on Slurry Boiling. Key. Eng. Mater., (766):1-6.
Studart, A.R., Gonzenbach, U.T., Tervoort, E., and Gauckler, L.J. (2006). Processing routes to macroporous ceramics: a review. J. Am. Ceram. Soc., 89(6):1,771-1,789.
Zhang, L.Y., Zhou, D.L., Chen, Y., Liang, B., and Zhou, J.B. (2014). Preparation of high open porosity ceramic foams via direct foaming molded and dried at room temperature. J. Eur. Ceram. Soc., 34(10):2,443-2,452.
