Cathodic Arc Synthesis of Sand-Erosion Resistant, Boride Coatings for Titanium Alloy Compressor Impeller Blades

In environments where the atmosphere can contain a high concentration of sand, the erosion of jet engine turbine blades becomes a dominant mechanism for reduced aircraft engine lifetime. NAVAIR is seeking a coating solution that will dramatically decrease this sand erosion wear mechanism, especially for titanium alloy impeller blades in the compressor side of its aircraft engines. HY-Tech is offering to apply its surface treatment technology, which is uniquely able to apply a super-high hardness (3 times that of sand), yet low modulus (i.e. elastic, providing good impact resistance), boron-rich thin film coating, with excellent adhesion to titanium alloys (as well as steels). The adhesion is achieved without the need for a bond coating, by using the energetic ions of boron involved in this process to form a reacted diffusion layer. Boron forms strongly bonded compounds with titanium; the compounds themselves are also hard and erosion resistant. The Phase I project will seek to demonstrate this solution by means of sand erosion testing of boron-coated flat-samples at a qualified facility and to determine the relationship of sand erosion performance to the depth and quality of the reacted layer.