Plasma deposited carbon containing zirconia films as thermal barriers

Carbon containing zirconia films are deposited from chemical vapor deposition (CVD) and from plasma enhanced chemical vapor deposition (PECVD), as being used as thermal barrier coatings for many applications. Their thermal conductivity has been measured for temperatures ranging from room temperature up to 450 K using the 3 ? method. It is shown that the samples exhibit a lattice and an electronic contribution to the thermal conductivity reaching values up to 13 W/m/K for samples from CVD and up to 5 W/m/K for the samples from PECVD at 450 K. At room temperature, the thermal conductivities for PECVD films are in the range of 1 W/m/K, whereas the CVD film shows values of 8 W/m/K. The large differences are explained by the microstructure of the films, showing smaller grain sizes with poor interfaces for the PECVD films compared to the denser CVD films. This shows that plasma deposited carbon containing zirconia films may serve as excellent thermal barriers.