Thermal Conductivity of Porous Alumina-Zirconia Prepared by Foam Technique for Applications in Cooling Systems of Artificial Satellites

Porous ceramics are of great interest due to their numerous potential applications. The objective of the present investigation was to produce porous alumina with 3 mol % yttria-stabilized tetragonal zirconia (Y-TZP). This material will be used in cooling systems of satellites. To obtain the porous ceramics the direct foaming technique was used. This method is based on the preparation of a stable foam to which a slurry of alumina and zirconia is added. The mixture is then vigorously stirred for incorporation of air. The sintered ceramics were characterized by scanning electron microscopy, mercury porosimetry and thermal conductivity. The tests performed with the porous alumina-zirconia ceramic composite obtained by this method, showed low thermal conductivity values, high porosity and uniform microstructure with 20-100 mu m open pores. The results show that the alumina-zirconia composites tested in this study have a potential for application in loop heat pipes of cooling systems of satellites.