Thermal conductivity issues of EB‐PVD thermal barrier coatings

Abstract

The thermal conductivity of electron-beam physical vapor deposited (EB-PVD) thermal barrier coatings (TBCs) was investigated by the Laser Flash technique. Sample type and methodology of data analyses as well as atmosphere during the measurement have some influence on the data. A large variation of the thermal conductivity was found by changes in TBC microstructure. Exposure at high temperature caused sintering of the porous microstructure that finally increased thermal conductivity up to 30 %. EB-PVD TBCs show a distinct thickness dependence of the thermal conductivity due to the anisotropic microstructure in thickness direction. Thin TBCs had a 20 % lower thermal conductivity than thick coatings.

Effect of processing and interface on the durability of single and bilayer 7YSZ / gadolinium zirconate EB-PVD thermal barrier coatings

“…the columns all grow through and do not change in thickness or number at this interface. This is identical to findings for 7YSZ layers that were originating from three separate interrupted runs [33] where columns grew through from one layer to the next without any interruption. Only minor variations in porosity were found in this study at the interface regions.…”

Influence of the deposition energy on the composition and thermal cycling behavior of La2(Zr0.7Ce0.3)2O7 coatings

“…(4) It exists a correlation between the chamber pressure and composition change during deposition. 5,24 The change in vapor pressure during deposition probably turns out to affect heavily the chamber pressure leading to deviate of composition. (5) The melting and evaporation behavior of the source material, ingot density, deposition rate and efficiency, gun power, e-beam focus, dwell time, chamber pressure and vapor cloud geometry are predominant factors to control the coatings' composition during deposition.…”

Influence of temperature on thermophysical properties of EB-PVD porous coatings and dense ceramics of 4mol% Y2O3-stabilized ZrO2

“…The thermal conductivities of EB-PVD coatings decrease slightly with increasing temperature. It was reported that thermal conductivity of partially yttria-stabilized zirconia (P-YSZ) EB-PVD coatings decreased with increasing temperature [14]. In addition, it is apparent that the thermal conductivities of the coatings are remarkably lower than those of the sintered samples.…”

“…Some investigations have already been reported regarding the relationship between the thermal conductivity and the microstructure of TBCs [14][15][16][17][18][19][20].…”