超音速火焰喷涂抗水蚀涂层应用于核电汽轮机叶片的可行性分析

Feasibility Analysis for Application of Water-Erosion Resistant Coatings on Steam Turbine Blade in Nuclear Power Plant

核电站汽轮机末级叶片因水蚀损伤,其表面形成微裂纹,在应力作用下叶片容易发生开裂,形成机组安全运行隐患。对比分析了常规火电及核电汽轮机运行蒸汽环境的不同,在此基础上,采用超音速火焰喷涂在0Cr17Ni4Cu4Nb(17-4PH)合金表面制备NiCr-Cr_3C_2抗水蚀层。采用扫描电镜观察涂层形貌,测试了涂层的硬度及耐冲蚀性。研究了抗水蚀涂层直接替代司太立用于17-4PH基材的可行性及此工艺用于修复叶片的可行性,并进行了现场模拟喷涂。结果表明:17-4PH合金表面超音速火焰喷涂抗水蚀涂层性能满足要求,可反复喷涂,在核电汽轮机末级叶片中的应用具有可行性。

The surface microcrack of last stage blades in nuclear power plant steam turbine is formed due to the water erosion and further is prone to developing under stresses,which causes the hidden dangers of the unit safe operation.In this paper,the differences of running steam environment between the conventional thermal power and nuclear power steam turbine were investigated,and the NiC r-Cr3C2 water erosion resistant coating was prepared by supersonic flame spraying on0Cr17Ni4Cu4Nb( 47-4PH) alloy surface. Coating morphology was observed by a scanning electron microscopy and the coating hardness and abrasion resistance were measured. The feasibilities that the water erosion resistant coating could directly replace 17-4PH base material and the technology could be used to repair the blades were investigated. Furthermore,the site simulation spraying was conducted. Results showed that the strength of the supersonic flame spraying coating on 17-4PH alloy surface met the requirement and the repeated spraying could be carried out,demonstrating the feasibility for application of the coating in steam turbine last blade in nuclear power plant.