Toward Durable Thermal Barrier Coating with Low Thermal Conductivity Superiority: Material Design, Process Optimization and Performance Evaluation

Today’s high-efficiency turbine engines highly rely on the further improvement of the novel technologies related to combustion, cooling and thermal barrier coating (TBC) with the increase in turbine inlet temperatures. As a result, thermal barrier coatings with higher thermal stability and lower thermal conductivity (low-k) than current PS-YSZ TBC had attracted a lot of academia and industries’ attentions, interests and activities. The present work is to focus on exploring a path toward a durable TBC with low-k capability by addressing the technical, practical and economic barriers for current low-k TBC development and applications. The concept of dual-phase composite ceramics was proposed for low-k TBC material design, in an effort to combine the desirable attributes of unique phase constitution, low conductivity k, high ceramic fracture toughness and good process economy. Further, thermal spray process was optimized specially for the topcoats of the low-k ceramics by controlling and measuring the effect of key process parameters on porous coating architecture, deposition rate and efficiency. To evaluate the performance of the low-k TBCs, both an isothermal oxidation test and a thermal cycling test were conducted. The test results of the dual-phase ceramics reveal promising for durable low-k TBCs measured by several desirable attributes