SBIR-STTR Award

Innovative damping methods for small turbine engines are needed by the Army and other military and commercial interests. The plasma sprayed coating process provides a method for successfully achieving the required damping for the newer high efficiency turbine engines that experience high "g " loads between 800 øF and 2000 øF. Plasma sprayed ceramic coatings have demonstrated significant damping from room temperature to 600 øF when impregnated with viscoelastic polymeric materials. The Phase I project will investigate methods of plasma spraying thin (100 to 300 mm thick) metal and/or ceramic damping coatings containing high temperature materials that exhibit viscoelastic properties (VEM) applied to super alloy test plates and simulated airfoils. The plasma spray process will be optimized to achieve maximum damping values while maintaining the required mechanical coating properties, including tensile, shear, and fatigue strength. Other coating properties of interest in the Phase I Option include erosion resistance and "creep" resistance of the VEM. The studies will include the use of high temperature materials with viscoelastic properties for use between 800 øF and 2000 øF. These VEM materials will be blended or otherwise incorporated with the ceramic plasma spray powder feedstock before plasma spraying in an effort to create unique damping coatings for small turbine engines

The Army’s new turbine engine airfoil designs have the potential of increased high cycle fatigue. The current Phase I SBIR program demonstrated the usefulness of plasma sprayed damping coatings to produce significant damping on Hastelloy X at temperatures between 1000 and 1500 °F. Concentrations of as little as 1% high temperature viscoelastic additives exhibited significant damping. The metal oxide powder blends were successfully plasma sprayed on Hastelloy X test specimens. The coating bond strength and microstructure were essentially unaffected by the incorporation of high temperature viscoelastic materials (VEM's) in the ceramic feed stock. The Phase II SBIR program will investigate in more detail the effect of plasma spray process variables on the plasma sprayed coating’s mechanical and damping properties. In particular, the effect of high “g” loads on the mechanical and damping properties of candidate ceramic/VEM blends will be investigated. The Phase II studies will also include damping, fatigue, erosion, and impact testing. Candidate VEM's will be selected to achieve maximum damping over a range of temperatures between 800 °F and 2000 °F. The plasma spray process is an accepted method of applying high temperature erosion, corrosion, and heat resistant coatings to jet engine components. The Phase II program will demonstrate the ability of plasma sprayed ceramic/VEM coatings to provide damping to military and commercial turbine engines at high temperature.

Keywords:
Turbine Engine Damping, Damping Coatings, High Cycle Fatigue, High Temperature Damping, Plasma Sprayed Coatings,Ceramic Damping Coatings