Optimization selection of the thermal conductivity of the top ceramic layer in the Double-Ceramic-Layer Thermal Barrier Coatings based on the finite element analysis of thermal insulation

摘要

The Double-Ceramic-Layer Thermal Barrier Coating (DCL-TBC) consists of a top ceramic layer (TC1), an inside ceramic layer (TC2), bond coat and alloy substrate. A FE numerical model had been developed to calculate the temperature of the DCL-TBC. The influence of the thermal conductivity of the TC1 layer was investigated based upon the temperature calculation results. The temperatures of the TC2 layer and the BC layer are decreased as λ_(TC1) increases; however the temperature of the TC1 layer will be increased. These two points indicate that too large and too small values of λ_(TC1) are all unfavorable. A reasonable range of λ_(TC1) should exist and ensure that the temperatures in the whole DCLTBC could be in the safe state. The reasonable range of λ_(TC1) was investigated based on the temperature calculated and the sintering temperature of each layer. If the thickness ratio of two ceramic layers is 150 μm-150 μm, the reasonable range of λ is from0.492 Wm~(?1) K~(?1) to 1.654 Wm~(?1) K~(?1). The reasonable range of λ_(TC1)was investigatedwith considering different thicknesses of the TC1 layer. The relationship between the reasonable range of λ_(TC1) and the thickness of TC1 (H_(TC1)), which is shown by the safe region of λ_(TC1)-H_(TC1), is established.