Ceramics with ultra-low density fabricated by gelcasting: en unconventional view

Autores: Ruifeng Chen|Yong Huang|Chang-An Wang|Jianqiang Qi
Fuente: J. Am. Ceram. Soc.
en prensa
2007

Gelcasting is conventionally used to acquire high-density ceramic parts; however, in this work, alumina (Al2O3) ceramics with ultra-low density (8%?40% theoretical density) were successfully fabricated by this method. In this research, polymerization of acrylamide was realized in tert-butyl alcohol/Al2O3 slurries with solid loading ranging from 5 to 15 vol%. Green bodies with ultra-low density could be dried with very small shrinkage, and relatively high green strengths (1?3 MPa) were achieved. By choosing different initial solid loadings and sintering temperatures, ceramic microstructures could be effectively controlled, with the porosity ranging from 60% to 92% and pore sizes from 0.1 to 2.2 µm. Sintered Al2O3 showed high open porosity (90%), high specific area (14 m2/g) and high compression strength (>10 MPa), which was attributed to the connection of Al2O3 particles. This technique is considered potentially useful in many applications, and introduces a new application field of gelcasting.