Thermal Confuctivity Porous Ceramics

Porous ceramics were prepared by different methods to achieve pore volume fractions from 4 to 95.

Thermal confuctivity porous ceramics.

The electrical resistivity of 100 cm is too high to be machined. Zirconia and alumina are generally chosen as tbc top coat material. Ceramics with low thermal conductivity e g. A clay based material exhibiting high pore volume fraction and low thermal conductivity suitable for thermal insulation is described.

The thermal conductivity of porous alumina ceramics prepared using different types of starch potato wheat corn and rice starch as pore forming agents has been investigated from room temperature up to 500 c. The thermal resistance of tbcs depends not only on the thermophysical properties of the ceramics but also on their microstructure. The compressive strength could be improved significantly by increasing the sintering temperature. Thus the reported thermal conductivity and electrical resistivity were 47 270w m k and 100 1011 cm respectively.

The pore volume fraction was varied from 40 to 75. The thermal conductivity of porous alumina ceramics prepared using different types of starch potato wheat corn and rice starch as pore forming agents is investigated from room temperature up to 500 c. A toolbox of analytical relations is proposed to describe the effective thermal conductivity as a function of solid phase thermal conductivity pore thermal conductivity and pore volume fraction ν p. Ceramics have been developed by doping nitrogen into a sic lattice 7 however their thermal conductivity has not been reported.

Zirconia ceramic foams with porosity of 97 9 has low thermal conductivity of 0 027 0 004 w m k 1 which could be used as thermal insulation and refractory material. Starting with a commercial clay containing 75 kaolinite foams were made by mixing in water and methyl cellulose as a surfactant then beating. In the present study the newly developed porous sic ceramics exhibited a very low thermal conductivity of 0 047 wm 1 k 1 at a high porosity 72 4 that is comparable to the thermal conductivity of sic aerogel 0 049 wm 1 k 1 and even lower than the thermal conductivity 0 068 wm 1 k 1 73 5 porous of a nano sic particle compact without heat treatment. Gas pressure and temperature dependences of thermal conductivity of porous ceramic materials.