Abstract
Thermal conductivity of top-coats (TCs) for thermal barrier coatings (TBCs) were investigated related to their porosities. Two kinds of free-standing TCs were produced by an air plasma spraying with different spraying powers and some TCs were subjected to the heat treatment at 1000〜1300℃ in air. The various porosities were measured based on the principle of Archimedes. The thermal conductivity was determined according to calculation using the thermal diffusivity, the specific heat capacity and the bulk density. It was found that the thermal conductivity depends strongly on the porosity as well as the size and the shape of pores. The TC sprayed with the lower power has a lot of microcracks between lamellas and exhibits the lower thermal conductivity.
