| TiAl alloys are new types of high-temperature structural materials applied for aerospace and aircraft industry because of their low density, high strength and good creep-resistance. With the good performances of thermal insulation, high-temperature oxidation resistance, hot corrosion resistance, wear resistance and many other advantages, thermal barrier coatings (TBCs) is one of most advanced high-temperature protective coatings. It not only can prolong the service life of aeroenginge, but also can increase the engine power and reduce fuel consumption. Combine the advantages of both the substrate and coating material for purpose of some mechanical properties and environmental service demands. How to to get good structural materials and how to improve the TBCs'good high temperature thermal stability and excellent mechanical properties are becoming the current research focus. In this paper, traditional and nanostructured TBCs were prepared by the technology of plasma spraying and plasma spraying-laser remelting on TiAl alloy surface, respectively. In this investigation, the performance test results of wear resistance, high-temperature oxidation resistance and hot corrosion resistance of all these four coatings were compared. The major completed tasks are as follows:(1)The surface morphology microstructure and phase of the plasma-sprayed and laser-remelted traditional and nanostructured TBCs were compared. The results show that: with columnar crystal structure, the laser-remelted nanostructured TBCs has much better properties. The feasibility of fabrication nanostructured coatings by plasma spraying-laser remelting technology was verified.(2)The friction and wear experiments on TiAl alloy substrate and all four coatings were taken, After that, study wear resistance property of the coatings, according with analyzing the measured friction coefficient curve, mass loss and the surface morphology after experiment. Then, the friction and wear mechanism was discussed.(3)Study the performance of high temperature oxidation resistance on the TiAl alloy substrate and all the four coatings under 850°C, Nanostructured coatings can increase the toughness and strain tolerance. Laser remelting eliminates the pores and microcracks and formats a dense remelted layer. Which improve the coatings'property of high temperature oxidation resistance by means of changing the ways of the oxyden directly proliferate in the ceramic coatings.(4)The hot corrosion behaviors of TiAl alloy substrate and coatings in molten salts (75%Na2SO4+25%NaCl) at 850°C were studied. It showed that laser remelting closed the proliferation channels of the corrosive medium and inhibited the corrosion happening. |
