Abstract
Abradable coatings are utilised as sacrificial materials in low-pressure compressor casings, and in intermediate and high pressure compressors and seals. The adoption of abradable coatings allows for the clearance between compressor blades and casing to be minimised, increasing the overall efficiency of the engine. Quasi-static and dynamic experiments at different temperatures are conducted to characterise the mechanical response of a thermally-sprayed abradable seal coating. The material is composed of an aluminium continuum matrix and fairly well-dispersed polyester particles. Stress versus strain histories are measured in uniaxial tension and compression at strain rates ranging from 10-3 to 102 s-1, via non-standard experimental techniques. The material displays sensitivity to the strain rate and to the imposed temperature. The mechanical behaviour is brittle in tension while it exhibits higher strains to failure in compression. The material is characterised by a pronounced tension/compression asymmetry.
Highlights
Coatings are used in all engineering design scenarios when the desired surface properties are different from the desired structural material properties
Abradable coatings are utilised as sacrificial materials in low pressure compressor casings, and in intermediate and high pressure compressors and seals
Compression and tensile quasi static tests on METCO 601 abradable seal coating were conducted by means of a screw-driven universal testing machine used in conjunction with an environmental chamber equipped with resistive heating elements
Summary
Coatings are used in all engineering design scenarios when the desired surface properties are different from the desired structural material properties. Gas turbine coatings are employed in aerospace propulsion in various sections of jet engines subjected to different temperature, pressure and loading conditions for several purposes [1]. Their primary applications include fretting wear protection, thermal barrier, corrosion, oxidation and wear resistance enhancement. Thermal barrier coatings are utilised to protect combustion chamber, turbine blades and vanes and the exit nozzle. Erosion and wear resistant coatings are applied to compression blades and vanes and high pressure compressors drum and seal runners. Abradable coatings are utilised as sacrificial materials in low pressure compressor casings, and in intermediate and high pressure compressors and seals
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