Study on Structure-Matching Preparation of Spalling-Resistant Metal-Based Abradable Seal Coatings

Abstract

 The new generation of aero-engines has higher requirements for thrust-to-weight ratios，and the clearance between the blade-tip and the engine casing is one of the key factors affecting the efficiency of the engine.Preparing abradable seal coatings on the inner wall of the casing can effectively reduce airflow leakage and prevent the tip from rubbing against the casing，thus enable the engine to operate efficiently and safely.Abradable seal coatings usually have high porosity.However，high porosity tends to reduce the strength of the abradable layer/ceramic thermal barrier layer interface，leading to the overall spalling of the abradable coating.Therefore，the structure-matching design of abradable seal layer/ceramic thermal barrier layer interface was conducted.On the basis of ensuring the abradable seal function of the coating，while enhancing the spalling resistance at interface between the two.Firstly，numerical analysis showed that the increase in pores characteristic size and porosity at the interface of the abradable layer/ceramic layer would increase the spalling risk of the abradable layer along the interface.Secondly，a structure-matching design for the abradable seal coating was proposed，which involved adding a spalling-resistant transition layer near the interface.Finally，the combination of simulations and tests was carried out to optimize the thickness of the spalling-resistant transition layer，which confirmed that the transition layer could significantly improve the service life of the system.

Keywords

•  structure-matching；abradable seal coating|interface reinforcement|spalling-resistant transition layer|long life