核电厂小尺寸阀门内壁新型冲蚀减缓技术的研发应用

Development and application of anti-erosion technology for inner wall of small-sized drain valve used in nuclear power plant

以WCB钢为基材,采用国产化小型超音速火焰喷涂(HVOF)设备喷涂Ni60镍基合金涂层。通过扫描电子显微镜(SEM)及能谱仪(EDS)分析、显微硬度计测试、拉伸试验、磨粒磨损试验和冲蚀磨损试验,考察了Ni60涂层的组织形貌、微观结构、孔隙率、显微硬度、结合强度、耐磨粒磨损性能和耐冲蚀磨损性能,并对实际小尺寸疏水阀门内壁进行喷涂,分析该工艺的实际可行性。结果表明,所制备的Ni60涂层的孔隙率为(0.27±0.04)%,显微硬度为843 HV(载荷300 g),界面结合强度高达200 MPa以上。该涂层主要由弥散分布着碳化物等硬质相的Ni基固溶体组成,具有比WCB基材更优良的耐磨粒磨损和耐冲蚀性能,其冲蚀失效形式主要为犁沟加塑形变形。小尺寸阀门内壁经喷涂后,表面涂层质量及配合性均符合要求。

A Ni60 nickel-based alloy coating was prepared on WCB steel by using a small-sized HVOF(high-velocity oxy-fuel)spraying equipment made in China.The morphology,microstructure,porosity,microhardness,bonding strength,abrasive wear resistance,and erosion resistance of the Ni60 coating were studied by scanning electron microscopy(SEM),energy-dispersive spectroscopy(EDS),microhardness testing,tensile testing,abrasive wear testing,and erosion testing.The feasibility of HVOF spraying the inner wall of a small-sized drain valve was analyzed.The results showed that the Ni60 coating prepared had a porosity of(0.27±0.04)%,a microhardness of 843 HV at a load of 300 g,and an interfacial bonding strength higher than 200 MPa.The coating is mainly composed of Ni-based solid solution where carbides and other hard phases are well distributed,and its resistance to abrasive wear and erosion is better than that of the WCB steel substrate.The erosion failure mode of the coating is furrow and plastic deformation.After being sprayed,the quality of coating on the inner wall of the small-sized valve and its compatibility meet the technical requirements.