Alumina Heat Insulator Through Composite Poring Mechanisms

摘要

Crack-free alumina heat insulators with large sizes were successfully prepared through composite poring mechanisms. In the sintered bodies, there existed 1-2 mm big pores due to solid template and 60-200 μm small pores due to direct foaming, and porosities (84.9-90.4%) were accurately tailored by varying the amounts of added polymer balls and foaming agent. Thanks to the excellent mechanical and thermal properties including compressive strengths of 2.3-5.2 MPa, thermal conductivity as low as 0.23 W/mK, and 50-h creep strain of only 0.102% at 1200℃, they are potentially used as eco-friendly substitutions for ceramic-fiber insulators.