Study On The Thermal Insulation Porous Ceramics

Thermal insulation porous ceramics require high porosity, small and uniform distribution of the pores and high compressive strength. In this paper,the porous ceramics were firstly prepared by slip casting process, and sintered at high temperature. Then, the thermal propertyies, crystalline phase, sintering and mechanical properties of the ceramics were characterized by XRD diffraction, Archimedes's method and other analytical methods. In addition, the impact of mineralizer ZnO on MgO-Al2O3 system ceramics crystalline phase was investegated. MgO-Al2O3 system porous ceramics were prepared to study the mechanical properties and the structure of pore by compressive strength testing and microscopic image analysis. Finally, the relationship between the pore structure and the thermal properties of porous ceramics was discussed.The results show:(1) The ceramics was developed by sintering at 1500℃/3hrs. and composed of 50mol% MgO and 50mol% Al2O3, plus 3wt.% mineralizer ZnO. The crystalline phase of ceramics was MgAl2O4 phase. The density of the ceramic was 2.659g/cm3 and linear shrinkage rate was 2.45%.(2) The porous ceramics were prepared and composed of 50mol% MgO and 50mol% Al2O3, added 3wt.% Zinc oxide,0.5wt.% the foaming agent sodium dodecyl benzene sulfonate and 32wt.% of water, adjusted the slurry temperature and the PH value of the slurry. The pores of the porous ceramics were closed. Porosity was 59.77% and average pore size of the sample was 50μm. Compressive strength was 174.58MPA.(3) When the average pore size of the porous ceramics was same, the greater the porosity, the better the thermal insulation properties. When the porosity of the samples was same, the smaller average pore size, the better the thermal insulation properties.