In this study, the effect of flow rate ratio (R) and total flow rate (Q) on the surface temperature of thermal barrier coatings (TBC) was investigated using a newly developed small-scale methane-oxygen burner rig. Subsequently, the failure mode of electron beam physical vapor deposition (EB-PVD) TBC was examined, and the relationship between surface temperature and coating life was established. The surface temperature of the TBC was found to be strongly dependent on both the flow rate ratio and the total flow rate. Specifically, surface temperature exhibited a proportional relationship with total flow rate, while it showed an inverse relationship with flow rate ratio. The failure mode of the EB-PVD TBC involved a gradual increase in delamination from the rim to the center of the coin-shaped specimen, and this failure mode was found to be independent of surface temperature. Additionally, it was determined that the surface temperature of EB-PVD TBC has a perfectly inverse linear relationship with coating life. This finding implies that the derived linear regression line from the burner rig test can be directly used to predict coating life for any untested surface .temperature.

In this study, we developed a new vertical thermal gradient rig that uses methane-oxygen fuel. We conducted thermal gradient testing on a thermal barrier coating system, with a flame temperature of 1,900℃. Our results showed that the maximum surface temperature reached 1,065℃, while the temperature difference between the surface temperature and the temperature of the middle substrate (ΔT) was 70oC. Using the same torch as in this study, our finding suggest that the total flow rate of the flame should be above 12.4 LPM, and the gun distance should be less than 8 cm, to simulate a surface temperature of 1,300℃, while keeping the substrate temperature below 1,000℃. This will ensure that the flame is wide enough to cover the entire surface area of the thermal barrier coating.