Cohesion and Adhesion Interlayer of the Thermal Barrier Coatings Made of Cobalt Alloy MAR-M509

The manuscript presents microstructure, geometrical product specification and results of scratch tests performed on the interlayer of thermal barrier coating (TBC) with Rockwell’s intender. The TBC was provided by depositing two layers; metallic interlayer and external ceramic layer onto a plate coating made of cobalt alloy MAR-M509 in plasma spraying process. The surface of the casting was sandblasted with Al²O³ powder in an air stream before the TBC was introduced. Scratches were made along the cross-section from a mould material (MAR-M509) through metallic interlayer and external ceramic layer in the TBC. Friction force, friction factor and acoustic emission were recorded during the test. It has been proved that metallic interlayer in the TBC of ca. 200 μm thickness forms tough coating without pores with good cohesion values and very good adhesion values to the mould.