Next Generation of Abradable Coatings for Intermediate Gas Turbine Compressor Stages: Manufacturing Process Development

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A compressor blade must have a clearance gap between its tip and the engine casing to avoid the blade from seizing and damage. This gap is typically sealed with an abradable (soft) coating to prevent air flowing back over the blade tip during service. To allow safe operation at elevated temperatures typically found in high-pressure compressor stages (up to 500°C), abradable coating matrices are manufactured using secondary phases such as solid lubricants, to minimize the coating's material transfer and promote abradability. AlSi-hBN is a potential metal matrix-solid lubricant coating material successfully manufactured by means of plasma spraying [ref]. However, its abradability is currently limited, mainly due to the inability of the plasma spray process to retain a sufficient amount of hBN in the coating. The proposed project aims at determining if the pulsed gas dynamic spray process (PGDS) can be adapted and developed to produce Al-Si+hBN coatings with properties (microstructure, hardness, adhesion, abradability) meeting the industrial collaborator specifications. Fundamental research is required to increase the understanding of the PGDS application method mechanisms and its ability to improve AlSi+hBN coatings durability.