The overall objective of this program is to produce oxidation resistant metallic coatings with improved durability and reliability to be employed as both the standalone coatings and bond coats for TBCs Specific objectives include

1. Generate a detailed processing sequence to optimize the initial formation of thermally grown oxide (TGO) based on environmental control (e.g., temperature and partial oxygen pressure) of pre-oxidation for surface finished Pt-Al, MCrAlY, and MCRAlY with Si + Hf coatings to be used as both standalone coatings and TBC bond coats.

2. Demonstrate by testing specimens with various surface finishes, that the presence or absence of surface defects on coatings significantly influence the durability and reliability of coatings and demonstrate a production process to remove defects and provide the optimum surface finish for improved durability and reliability of coatings.

3. Demonstrate and define the mechanism(s) for improved oxidation resistance resulting adding Si and Hf to Pt-Al coatings.

4. Define cost-effective processing techniques for producing a perfect, initial TGO and an optimum surface finish free of defects for Pt-Al, Pt-Al (Si,Hf) and MCrAlY coatings. The process defined will be applicable to complex shaped engine components such as turbine blades.

5. Demonstrate that these TGO optimization techniques provide a 3X improvement in oxidation resistance from stand-alone metallic coatings and a 3X improvement in spallation resistance for 3 TBCs in the program.

6. Transfer the attained understanding to industrial partners for the rapid implementation of both the improved stand-alone coatings and TBC bond coats.

3.0 Program Organization, Plan and Schedule

University-Industry Partnership

Engine Developers GE Power Systems Pratt & Whitney Rolls-Royce Siemens Westinghouse Solar Turbines

Coating Supplier Howmet Technology

Figure 8 Program Organization

Task I

Heat Treatment and Ch aracterization of Stand-alone Metallic Coatings

• Heat Treatment and Characterization

• Process Selection for Task II and III

Task II

Oxidation Testing of Stand-alone Metallic Coatings

• Isothermal & Cyclic Oxidation/TGA A

• Evaluation and Ch aracterization

Task III

Testing and Evaluation of TBCs

• Cyclic Oxidation

• Evaluation / Characterization

Task V

Reports/Industrial Briefings/Technology Transfer

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