Self-Healing Materials for Tip Region Cracks Science & Technology Objective(s): Identify one or more self-healing materials that have potential for gas turbine component construction Demonstrate the ability of an emerging self-healing material for fan and/or compressor airfoils Photograph of spin Pit & Rub Shoe Advanced Materials Dunn & Mills (Ohio State) & Adams (Case Western) Collaborations: Government - NASA Glenn and U.S.Air Force URETI - Ohio State, Case Western Industry - GEAE, Rolls-Royce America, and P/W Synergism with existing programs - GEAE blade tip rub program at OSU Proposed Approach: Identify potential “smart materials” for airfoil and casing Extend “smart material” temperature range Incorporate entrained pockets of metal with good wetting properties NASA Relevance/Impact: Significant reduction in potential tip losses because of damaged airfoils Cost savings because airfoil replacement advantages Crack reduction should reduce blade-out potential Milestones/Accomplishments: Selection of potential materials Incorporation of entrained pockets of metal in material Demonstration of high temperature and strength capability of material selected Develop model for tip/casing rub dynamics Verify model with realistic measurements Tip rub measurement engine speed

Background Tip Rubs for Fans and Compressors are not Preventable –Airfoil material and rub shoe material influence what will happen to airfoil –Tiny cracks can and do develop as a result of these rubs and propagate into the airfoil –Potentially result in loss of a portion or all of airfoil Emerging “Smart Materials” Offer Potential for Helping to Mitigate Crack Problem Crack Needs to “heal Instantaneously” for Material to be Useful

Proposed Approach Select Potential “Smart Material” that may Work for this Purpose, i.e. entrained Mg forming MgO –Material should be capable of operating at high stress/strain elevated temperature –Material will also need to be capable of operating with entrained pockets of metal for “healing” purposes Develop Analytical Model to Describe Interaction Between Selected Material and Potential Casing Coating Materials –Demonstrate that model works for known cases of tip/casing rub Perform Measurement Engine Speed to Demonstrate “self healing” Capability of Material Selected