Preparation and property of seal coating for gas turbine compressor

Double-layer structure of seal coating which consisted of a Ni5Al bond coating and a Ni25 graphite top coating were prepared on steel substrate of gas turbine compressor cylinder block. Bond coating was prepared by atmospheric plasma spraying and top coating was prepared by flame spraying. The microstructure, mechanical properties and abradability of the coating were characterized by scanning electron microscope (SEM), hardness tester, universal testing machine, thermal shock testing machine and abradability testing machine. The results show that the overall spraying structure of the seal coating is uniform, the nickel metal phase is the skeleton supporting the entire coating, and the coating is well bonded without separation. The seal coating has a bonding strength of not less than 7.7 MPa, excellent thermal stability, and thermal shock resistance cycle numbers at 500 ℃ more than 50; the scratch length, deepest invasion depth and wear amount of the coating increase with rise of test temperature, with almost no coating adhesion, indicating that the seal coating has excellent abradability.