Modified-starch consolidation of alumina ceramics

Abstract

The alumina ceramics with the homogeneous microstructure and the higher density were fabricated via the modified-starch consolidation process by 1.0 wt% of a modified starch as a consolidator/binder. The swelling behavior of the modified oxidized tapioca starch was analyzed by optical microscope, and two other corn starches (common corn starch and high amylose corn starch) were also analyzed for comparison. The modified starch used as a binder for the consolidation swelled at about 55 °, began to gelatinize at 65 ° and then was completely gelatinized at 75 °. But the corn starches could not be completely gelatinized even at 80 ° for 1 h. The high-strength green bodies (10.6 MPa) with the complex shapes were produced. The green bodies were sintered without any binder burnout procedure at 1 700 ° and a relative density of 95.3% was obtained for the sintered bodies, which is similar to that of the sintered sample formed by conventional slip casting. In addition, the effect of temperature on the apparent viscosity of the starch/alumina slurry in the process was investigated, and the corresponding mechanism for the starch consolidation was discussed.

Keywords

oxidized starch / gelation / alumina ceramic / starch consolidation

References

[1] Lyckfeldt O., Ferreira J. M. F. Porous Ceramics by Starch Consolidation[J]. J. Eur. Ceram. Soc., 1998, 18: 131-140.

[2] Bowden M. E., Rippey M. S. Porous Ceramics Formed Using Starch Consolidation[J]. Key. Eng. Mater., 2002, 206–213: 1957-1960.

[3] E T., W P., E G. Starch Consolidation Casting of Alumina Ceramics-body Formation and Microstructural Characterization[J]. Key. Eng. Mater., 2002, 206–213: 1969-1972.

[4] O L., K R. Si₃N₄ Powders Applied for Waterbased DCT[J]. Ceram. Trans., 2003, 142: 47-62.

[5] Kuwabara M. Effect of Microstructure on the PTCR Effect in Semiconducting Barium Titanate Ceramics[J]. J. Am. Ceram. Soc., 1981, 64(11): 639-644.

[6] Kim J. G. Fabrication of Porous Ba(Ti, Sb)O₃ Ceramics and Electrical Properties[J]. Mater. Sci. & Eng. A, 2003, 347: 306-310.

[7] Kim J. G., Tai W. P., Ha J. G. PTCR Characteristics and Fabrication of Porous, Sb-doped BaTiO₃ Ceramics[J]. J. Porous. Mater., 2003, 10(1): 69-74.

[8] Kim J. G. Synthesis of Porous (Ba, Sr)TiO₃ Ceramics and PTCR Characteristics[J]. Mater. Chem. Phys., 2002, 78: 154-159.

[9] Rodríguez-Lorenzo L. M., Vallet-Regí M., Ferreira J. M. F. Fabrication of Porous Hydroxyapatite Bodies by a New Direct Consolidation Method: Starch Consolidation[J]. J. Biomed. Mater. Res., 2002, 60(2): 232-240.

[10] Vitale-Brovarone C., Di Nunzio S., Bretcanu O., . Macroporous Glass-ceramic Materials with Bioactive Properties[J]. J. Mater. Sci.: Mater. Med., 2004, 15(3): 209-217.

[11] Lemos A. F., Ferreira J. M. F. Porous Bioactive Calcium Carbonate Implants Processed by Starch Consolidation[J]. Mater. Sci. & Eng., 2000, 11(1): 35-40.

[12] Lu J. X., Flautre B., Anselme K., . Role of Interconnections in Porous Bioceramics on Bone Recolonization in Vitro and in Vivo[J]. J. Mater. Sci., 1999, 10: 111

[13] Lemos A. F., Ferreira J. M. F. Combining Foaming and Starch Consolidation Methods to Develop Macroporous Hydroxyapatite Implants[J]. Key Eng Mater, 2004, 254–256: 1041-1044.

[14] Kitamura M., Ohsuki C., Oqata S., . Fabrication of α-tricalcium Phosphate Porous Ceramics with Controlled Pore Structure[J]. J. Soc. Mater. Sci., 2004, 53(6): 594-598.

[15] Tari G. Gelcasting Ceramics: a Review[J]. Am. Ceram. Soc. Bull., 2003, 82(4): 43-46.

[16] Ju C. H., Wang Y. M., Ye J. D., . Effect of Particle Size Distribution on the Rheological Behaviour of Dense Alumina Suspensions[J]. J. Chin. Ceram. Soc., 2006, 34(8): 985-991.

[17] Chen Y. L., Xie Z. P., Yang J. L., . Alumina Casting Based on Gelation of Gelatine[J]. J. Eur. Ceram. Soc., 1999, 19: 271-275.