THERMAL-PROPERTIES AND MICROSTRUCTURE OF 2 THERMAL BARRIER COATINGS

Two plasma sprayed yttria stabilized zirconia coatings are described in terms of their microstructure. The structures differ widely as a result of controlling the coating density, and in one producing a vertical macrocrack pattern that segments the structure. The thermal properties, including thermal expansion, thermal diffusivity and specific heat, were measured from room temperature to 1200-degrees-C. The thermal conductivity was calculated from these properties. It was found that a small increase in thermal conductivity occurs as a result of the first heating cycle, and this effect was examined in relation to microstructure.