Platinum Substitutes and Glass Overlayers for Enhancing Nickel Aluminide Coatings
Small Business Information
107 Research Drive, Hampton, VA, 23666
Karl E. Wiedemann
AbstractPlatinum additions are currently used to enhance the effectivenss of nickel-aluminide coatings under severe service conditions. This study will determine the feasibility of new, less expensive alternatives. Nickel-aluminide coatings protect hot turbine engine parts from the effects of oxidation and hot corrosion. The coatings are protective when the aluminum activity near the surface is maintained at a high level. Aluminum near the surface is depleted through scale formation, and replenished through diffusion from the interior. Platinum additions enhance the protectiveness of nickel-aluminide coatings because they increase the aluminum replenishment rate. The new coatings will use two-phase-glass (TPG) overlayers that will reduce aluminum depletion rates, and less-expensive platinum group (Pg) additions that will maintain increased aluminum replenishment rates over nickel-aluminide coatings. Coupons with TPG overlayers and selected Pg aluminides will be prepared and subjected to short-term, realistic oxidation, hot corrosion, and thermal cycling tests on a laboratory scale. The best coatings will be selected for further testing in Phase II. Phase II will include fatigue studies, burner-fatigue testing plan is also proposed as a Phase I Option.
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