TECHNOLOGY AREAS: Air Platform, Materials/Processes

ACQUISITION PROGRAM: Joint Strike Fighter

OBJECTIVE: Develop a thin, lightweight, durable damping coating for turbine engine airfoils (Titanium or Nickel alloys) with dual-use capabilities (e.g. erosion and damping, thermal barrier and damping, or corrosion and damping).

DESCRIPTION: Modern high performance turbine engines have an inherently higher risk of high cycle fatigue (HCF) failures due to their increased work per airfoil and higher flows. Higher rotational speeds have caused new designs to use shorter necks in turbine airfoils or integrally bladed rotors (IBRs) in compressor airfoils, which result in reduced friction damping for the airfoil. Since new designs have inherently less friction damping, airfoil coatings are being investigated to provide damping and reduce HCF failures. Current turbine engine airfoils often have coatings for durability to increase time-on-wing. Coatings are also used on production engines to improve erosion resistance due to sand ingestion in the compressor (or fan), as a thermal barrier (TBC) in the turbine to reduce base metal temperatures, and to provide oxidation/corrosion resistance in the turbine. While the ability to avoid HCF failure would be highly beneficial, damping coatings have not been incorporated into current coating designs. The turbine engine industry is seeking a damping coating (or coating system) that will also improve overall blade life by providing the added effects of either thermal barrier or erosion coatings. A �dual-use� coating would provide a much greater cost benefit to the user while improving aircraft safety and reliability. Proposed techniques should be thin, lightweight, durable, should not significantly impact material fatigue, and will need to meet requirements for long-term turbine engine use. Total coating thickness should be 10 mils or less.

PHASE I: Demonstrate coating feasibility with appropriate (Titanium or Nickel alloy) specimens. For example, if the coating proposed is a TBC/damping coating for turbine use, testing should be performed on Nickel alloy specimens at elevated temperatures, or if the coating proposed is an erosion/damping coating for fan use, testing should be on Titanium specimens with erosion testing. Use specimen test to evaluate other pertinent properties (erosion resistance, HCF strength, etc.). Test results should quantify damping and material properties.

PHASE II: Develop a prototype coating and apply to an appropriate set of engine airfoils to demonstrate long term durability of the coating system. Demonstrate durability in appropriate combined load bench test or HCF spin test. Demonstrate manufacturing application method feasibility for typical engine components. Develop and validate design methodology for the new system including required engineering properties.

PHASE III: Apply coating to a set of engine-quality airfoils and submit hardware for engine demonstration in a government or industry-supplied asset. Finalize coating integration with and OEM on a current or development engine.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: An effective dual-use damping coating would increase airfoil lives and engine time-on-wing, while also increasing engine safety and reliability. The technology would be applicable to both commercial and military aircraft turbine engines.

REFERENCES:
1. B.A. Movchan, A.I. Ustinov, International Center for Electron Beam Technologies of E.O. Paton EWI of NAS, Ukraine, �Highly Damping Coatings for Protection o Titanium Blades� presented at NATO RTO AVT-121 Symposium.

2. Dr. Herman Shen, �Free Layer Blade Damper by Magneto-mechanical Coating� 10th National Turbine Engine High Cycle Fatigue (HCF) Conference, March 2005

3. Dr. John P. Henderson, Mr. Donald W. Zabierek, Mr. John A. Justice, and Mr Robert M. Wilson; �Preliminary Investigations of Modified Plasma Sprayed Damping Coatings for Titanium Airfoils� March 2005.

KEYWORDS: turbine engine; damping coating; airfoils; fatigue; erosion coating; thermal barrier coating

TPOC: (301)757-0462
2nd TPOC: (301) 757-045

** TOPIC AUTHOR (TPOC) **

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