目的 通过热喷涂涂层,解决 350 MW 超临界机组再热第一级静叶栅的高温冲蚀问题。 方法 采用超音速火焰喷涂制备了 NiCr-Cr₃C₂ 涂层,测试了涂层的显微组织、孔隙率、显微硬度、结合强度及高温冲蚀性能,并对涂层在冲蚀条件下的失效机理进行分析。 结果 实验室条件下, NiCr-Cr₃C₂ 涂层孔隙率为 0 . 98% ,显微硬度达到 1061 . 2 HV0 . 3 ,结合强度约为 80 MPa。 装机试车时,0 . 22 mm 厚的 NiCr-Cr₃C₂涂层可使再热第一级静叶的寿命延长 3 倍左右。 结论 采用 NiCr-Cr₃C₂ 涂层可显著延长静叶寿命,小角度粒子犁削冲蚀是涂层加速失效的主要原因。

Objective To solve the problem of high temperature erosion, thermal spray coating was prepared and studied on 350 MW supercritical unit reheated level stator cascade. Methods High velocity oxygen fuel spraying ( HVOF) was used to prepare NiCr-Cr₃C₂coating. A series of coating performance were tested, such as microstructure, porosity, micro-hardness, adhesion strength and high temperature erosion performance. And then the failure mechanism of coating in the erosion conditions was analyzed. Results Under the laboratory conditions, the coating porosity was 0 . 98 % , the value of micro-hardness HV0 . 3 was 1061 . 2 ,and the bonding strength was about 80 MPa.Under the working conditions of the stream turbine, when the thickness of coating was 0 . 22 mm, the service life of the first reheated level stator cascade was 3 times longer than the original . Conclusion The service life of stator cascade can be prolonged after using NiCr-Cr₃C₂coating. The main reason for the accelerated failure of the coating is plough erosion of small angle particles.