Enhanced CBN Blade Tip Systems for Improving Engine Efficiency

Abstract Clearance-control coatings play a major role in gas turbine engines by minimizing the air gap between rotating blade tips and engine casings. An improvement of just 125 µm can reduce fuel consumption by 0.5%. This article discusses the potential impact of new materials being considered for blade tip coating systems, including NiCoCrAlY bond coats and matrix layers with Hf, Re, or Si additions for better oxidation and creep resistance, embedded angular CBN particles for enhanced incursion of abradable shroud coatings, and double or Pt aluminide topcoats for extended oxidation protection.