RESEARCH ON THE HEAT INSULATION PERFORMANCE OF ADVANCED THERMAL BARRIER COATINGS BASED ON DENSE VERTICAL CRACKED STRUCTURE

摘要

The Thermal barrier coatings (TBCs) applied to gas turbine can effectively protect the metallic components from overheating. It makes contribution to raising turbine entry temperatures, which can improve the cycle thermal efficiency of turbine and prolong its service life. To understand the failure mechanism of TBCs and extend its lifetime, it is vital to prepare TBCs with excellent heat insulating performance. TBCs with dense vertical cracked structure is an essential kind of advanced thermal barrier coatings and has received great attention recently. However, most studies are based on laboratory-scale, since the complex coating preparation process makes it challenging to obtain the controllable microstructure distribution of the coating. Moreover, the thin slices of TBCs are difficult to get during the reconstruction process of the coating microstructure. Therefore, in this work, an optimized numerical reconstruction method of TBCs was applied to obtaining the TBCs with dense vertical cracked structure. The influences of the microstructural TBCs with different numbers of vertical cracks as well as different length and width of vertical cracks were herein discussed, together with the analysis by the developed numerical calculation program based on the lattice Boltzmann method (LBM). The results showed that the performance of heat insulation in dense vertical cracked coatings was improved as the characteristic network structure. Meanwhile, it indicated that the optimal heat insulation performance can get when the length and width of vertical cracks were around 125pm, 15pm respectively. The results can play a guiding role in choosing and designing the turbine blades for further development of gas turbines.