Abstract
The efficiency of gas turbines is highly dependent upon the clearance between compressor housing and rotating blades. Abradable seal coatings are employed to minimize the clearance and control the over-tip leakage by allowing the blade tips to cut into the coating and herewith implementing a method of self-adjustment. These coatings consist of a thermally sprayed multiphase material, comprising a metal matrix, a dislocator and a defined level of porosity. Thermally sprayed abradable linings aim at a well balanced profile of properties relevant for the application as abradable seals. Amongst others these include: abradability, ageing resistance, corrosion and oxidation resistance as well as surface finish and bond strength to substrate materials. Due to the high demands in aircraft industry, the coating properties also have to match strict requirements with regards to quality control. Hence the spraying process has to be stable and well controlled. In this work, an APS sprayed abradable coating was sprayed with different sets of parameters and analysed by an on-line diagnostic system. The coating microstructure and properties were evaluated and related to the diagnostic results.
