Preparation Of Light-weight Heat-resistant Ceramics Using Fly Ash Cenosphere As Raw Materials

This paper prepared light-weight heat-resistant ceramics using fly ash cenosphere as raw materials for the purpose of preparing heat insulation materials with low density, high strength and good insulation properties. Porous ceramics were prepared by gel-casting with fly ash cenosphere as pore former and ZrO2 and Al(OH)3 sol as binding agents. Firstly, the effects of fly ash cenosphere and sintering temperature on the properties and microstructure of porous ceramics were discussed to obtain the optimal formula and sintering temperature.Secondly, porous ceramics were prepared with different particle sizes of fly ash cenosphere, and the properties and microstructure were studied. Finally, the difference of properties of porous ceramics prepared by two different binding agent wered discussed.Results showed that the light-weigh porous ceramics were prepared by adding 30% fly ash cenosphere with the density 1.35 g/cm3, apparent porosity 65%, water absorbtion 45%, bending strength 7.5 MPa and thermal conductivity 0.226 W/(m.K), which is sintered at 1400 oC with ZrO2 as binding agent. Light-weigth porous ceramics with higher strength were prepared by fly ash cenosphere of 40-150 particle size, and the bending strength rose, porosity and water absorbtion decreased, density increased with the particle size of fly ash cenosphere decreasing. And the light-weigh porous ceramics with the density 1.0 g/cm3, apparent porosity 60%, water absorbtion 58.4%, bending strength 7.2 MPa, compressive strength 11.2 MPa, thermal conductivity 0.27 W/(m.k) were prepared by adding 45% fly ash cenosphere, which is sintered at 1400 oC with Al(OH)3 sol as binding agent. Compared with ZrO2, using aluminum hydroxide sol as binder can obtain low apparent porosity, low density(1.0 g/cm3) and high strength by increasing the addition of fly ash cenosphere to 45%, but it had larger volume shrinkage and water absorbtion.