A Study of Advanced Materials for Gas Turbine Coatings at Elevated Temperatures Using Selected Microstructures and Characteristic Environments for Syngas Combustion

Ravinder Diwan ; Patrick Mensah ; Guoqiang Li ; Nalini Uppu ; Strphen Akwaboa ; Monica Silva ; Ebubekir Beyazoglu ; Ogad Agu ; Naresh Polasa ; Lawrence Bazille ; Douglas Wolfe ; Purush Sahoo

关键词: COATINGS;    CORROSION;    DIFFUSION;    ELECTRON BEAMS;    GAS TURBINE ENGINES;    GAS TURBINES;    GRAIN BOUNDARIES;    KINETICS;    MICROSTRUCTURE;    MORPHOLOGY;    OXIDATION;    OXIDES;    PHYSICAL VAPOR DEPOSITION;    PLASMA;    POROSITY;    SYNTHESIS GAS;    TEMPERATURE GRADIENTS;    THERMAL BARRIERS;    THERMAL CYCLING;    TURBINE BLADES;   

DOI  :  10.2172/1017494
RP-ID  :  None
PID  :  OSTI ID: 1017494
Others  :  TRN: US201113%%727

学科分类：航空航天科学

美国|英语

来源: SciTech Connect

【 摘 要 】

Thermal barrier coatings (TBCs) that can be suitable for use in industrial gas turbine engines have been processed and compared with electron beam physical vapor deposition (EBPVD) microstructures for applications in advanced gas turbines that use coal-derived synthesis gas. Thermo-physical properties have been evaluated of the processed air plasma sprayed TBCs with standard APS-STD and vertically cracked APS-VC coatings samples up to 1300 C. Porosity of these selected coatings with related microstructural effects have been analyzed in this study. Wet and dry thermal cycling studies at 1125 C and spalling resistance thermal cycling studies to 1200 C have also been carried out. Type I and Type II hot corrosion tests were carried out to investigate the effects of microstructure variations and additions of alumina in YSZ top coats in multi-layered TBC structures. The thermal modeling of turbine blade has also been carried out that gives the capability to predict in-service performance temperature gradients. In addition to isothermal high temperature oxidation kinetics analysis in YSZ thermal barrier coatings of NiCoCrAlY bond coats with 0.25% Hf. This can affect the failure behavior depending on the control of the thermally grown oxide (TGO) growth at the interface. The TGO growth kinetics is seen to be parabolic and the activation energies correspond to interfacial growth kinetics that is controlled by the diffusion of O{sub 2} in Al{sub 2}O{sub 3}. The difference between oxidation behavior of the VC and STD structures are attributed to the effects of microstructure morphology and porosity on oxygen ingression into the zirconia and TGO layers. The isothermal oxidation resistance of the STD and VC microstructures is similar at temperatures up to 1200 C. However, the generally thicker TGO layer thicknesses and the slightly faster oxidation rates in the VC microstructures are attributed to the increased ingression of oxygen through the grain boundaries of the vertically cracked microstructures. The plasma sprayed TBC microstructure (VC and STD) with NiCoCrAlY-Hf bond coat are stable up to 1100 C. However, as with other TBC structures, a considerable amount of interdiffusion was observed in the different layers, although the TBC growth was self-limiting and parabolic. The addition of Hf to the VC microstructure appears to have some potential for the future development of robust TBCs with improved isothermal and service temperatures in advanced gas turbines.