Thermal Confuctivity Porous Ceramics

The pore volume fraction was varied from 40 to 75.

Thermal confuctivity porous ceramics. A clay based material exhibiting high pore volume fraction and low thermal conductivity suitable for thermal insulation is described. Ceramics have been developed by doping nitrogen into a sic lattice 7 however their thermal conductivity has not been reported. 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. 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.

Microstructural characterisation was performed including the determination of the pore size distribution psd. The electrical resistivity of 100 cm is too high to be machined. 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.

Gas pressure and temperature dependences of thermal conductivity of porous ceramic materials. Ceramics with low thermal conductivity e g. Thus the reported thermal conductivity and electrical resistivity were 47 270w m k and 100 1011 cm respectively. The thermal resistance of tbcs depends not only on the thermophysical properties of the ceramics but also on their microstructure.

Starting with a commercial clay containing 75 kaolinite foams were made by mixing in water and methyl cellulose as a surfactant then beating. Porous ceramics were prepared by different methods to achieve pore volume fractions from 4 to 95. Part 2 refractories and ceramics with porosity exceeding 30 efim litovsky laboratory of transport processes in porous materials faculty of mechanical engineering technion israel institute of technology haifa 32000 israel. Zirconia and alumina are generally chosen as tbc top coat material.