Plasma spray parameters to optimize the properties of abrasion coating used in axial flow compressors of aero-engines to maintain blade tip clearance

Abstract

This paper deals with the casing surface and blade tip clearance in an axial flow compressor in aero-engines. The clearance in between the tips of the blade and the casing surface should be optimized by considering the thermal and internal expansion as well as changes in concentricity due to shock loading events, to prevent catastrophic tip to casing contact. These parameters play a significant role in the efficiency enhancement of aero-engine. Generally, In case of shock loading, the tip of the blade severely damages the casing surface, which is a primary concern of an aero-engineer. To protect the tip as well as the casing, there is a coating developed called abradable coating, which is not only to allow for closer clearances. But to automatically adjust clearances, in-situ, to accept physical events and thermal variation that may be found during its exploitation. An abradable coating must have sufficient strength and hardness to resist the rigidness of aero-engine handling during assembly, transportation, and exploitation. At the same time, it must be soft enough to allow the axial flow compressor rotor blades to cut through it easily without getting pilled off in lumps. The current investigation is done to optimize the plasma coating parameters such as Powder feed rate, Plasma power, powder grain size, Gun Velocity, spray distance, Argon/hydrogen ratio, and their pressure, etc.