Integrated Approach for the Development of Advanced, Coated Gas Turbine Blades

Abstract

This paper describes a through‐process modelling on a microstructural level of the production of a coated turbine blade, including its in‐service properties and degradation, accompanied by the actual production and testing of a CMSX‐4 single crystal turbine blade dummy. The following steps are dealt with by modelling and experiment: solidification of the blade alloy during casting, microstructural changes during homogenization and aging heat treatments, chemical vapour deposition of an Al2O3 diffusion barrier coating, physical vapour deposition (sputtering) of a (Ni,Co)CrAlY bond coat, atmospheric plasma spraying of an Y2O3 stabilized ZrO2 thermal barrier coating and microstructural changes and development of critical stresses at in‐service conditions. This work forms a part of the Collaborative Research Centre 370 (SFB 370) “Integrative materials modelling”.

(Ln0.9Gd0.05Yb0.05)2Zr2O7 Ceramics with Pyrochlore Structure as Thermal Barrier Oxides

“…[1][2][3] Up to now, the most successful TBC materials in use are 7 ± 1 wt.%Y 2 O 3 stabilized ZrO 2 (7YSZ). However, 7YSZ is limited to operate below 1200°C.…”

Modeling of Coating Process, Phase Changes, and Damage of Plasma Sprayed Thermal Barrier Coatings on Ni‐Base Superalloys

“…The work within the SFB 370 was focused on the analysis and modeling of the different process parts, so called sub-processes models of the APS. [17] The following Transfer Project (TFB 63) ''Applied modeling tools'' had the objective to integrate the developed sub-process models in a user-friendly simulation tool for industrial application in the process controlling and production development of TBCs for gas turbine blades. The simulation tool should provide the input of characteristic process parameters via a graphical user interface together with the analysis of the simulation results.…”

“…The tensile out-of-plane stresses caused by in-plane compression at undulations of the interface may lead to delamination of the TBC. [17,49] Because turbine inlet temperature in modern gas turbines exceeds the melting point of the substrate alloy, delamination has to be definitely excluded to avoid catastrophic failure of the component. In this field, existing FEM models had to be extended by appropriate approaches for modeling delamination crack propagation along the BC/TBC interface as well as in the TBC itself, taking into account experimental data from mechanical testing of free standing TBCs and of layered structures.…”

“…TGO creep was fitted into a classical Norton creep law from literature data for solid a-Al 2 O 3 . [50] _ e ¼ A Á s n (17) In both Equations (16) and (17), s is stress and _ e is strain rate. TGO growth kinetics was described by a power law combined with thermal activation:…”

“…[49] Results from parameter studies on the influence of interface roughness, creep properties of all components, TBC stiffness and different temperature cycles are given in Refs. [17,49,51] Simulation of Transversal Crack Propagation in the BC and Substrate During Thermomechanical Fatigue To analyze out-of plane crack growth during thermomechanical fatigue (TMF), the model described above was modified as follows: (i) According to service experience and experimental findings, which prove that TBC has no significant influence on crack initiation under TMF loading, [48] only the substrate, the BC and the TGO (including growth stresses) were considered in the model. The TBC layer was removed from the model.…”