Research On Microstructure And Properties Of Whisker And Rare Earth Modified YSZ-based Thermal Barrier Coatings

Thermal barrier coating(TBCs)has become an integral part of high performance gas turbines due to its excellent thermal insulation,oxidation resistance.Yttrium oxide stabilized zirconia(YSZ)is the most mature TBCs material available.During the service of TBCs,the accumulation of thermal stress will cause cracks in the coating,causing premature failure of the coating and loss of protection.In this paper,whisker was added to YSZ plasma spraying thermal barrier coating to improve fracture toughness and prolong service life of the coating.In the explosion-sprayed YSZ-based coating,the rare earth oxide was doped,and the whisker and rare earth were co-doped.The changes of coating structure and other properties were studied.The law of rare earth luminescence in the coating under different conditions was discussed.Research indicatesThe addition of AlBOw and BNw in plasma sprayed YSZ-based coatings increased the porosity,fracture toughness and erosion resistance of the coatings.Whisker inhibits crack propagation through crack deflection,whisker extraction,and whisker bridging,extending the life of the coating.However,the influences of the two whiskers on the thermal shock resistance of the coating are quite different.The thermal shock resistance of the coating added with AlBOw is slightly lower than that of YSZ coating,and the thermal shock resistance of the coating added with BNw is 62.2%higher than that of YSZ coating.The doping of rare earth oxides Eu2O3 and Nd2O3 has similar effects on the micro structure and properties of the explosion-sprayed YSZ-based coating.The phase structure of the rare earth doped coating consists of the t phase.As the doping amount of rare earth increases,the porosity of the coating decreases,the microhardness and fracture toughness are improved.With the increase of rare earth doping amount,the bonding strength of the coating increases first and then decreases.When the doping amount of Eu2O3 and Nd2O3 is 1%,the thermal cycle number of the coating is the highest,185 times and 200 times respectively.The thermal shock failure mode of the coating is mainly the flake peeling inside the ceramic layer.The luminescence intensity of the sprayed coating increases as the doping amount of the rare earth oxide increases.After experiencing the thermal shock test failure,the luminescence intensity of the Eu2O3 doped coating decreased to some extent;the Nd2O3 doped coating produced a new luminescence peak at 524 nm.In the YSZ-based coating modified by whisker and rare earth,the porosity of the coating increased by 23.5%with the 10%increase of whisker,and the microhardness and bonding strength decreased.However,the increase of whiskers increased fracture toughness and thermal shock resistance by 8.5%and 9.9%respectively.With the increase of whisker content,the luminescence intensity of sprayed coating decreased After the thermal shock test,the emission spectrum of the coating produced a new emission peak at 594 nm.