堆内构件钴基合金熔覆层组织及性能研究

Microstructure and Properties of Cobalt-based Alloy Coatings on Nuclear Internal Components by Cladding

目的确保堆内构件的限位精度,防止由于磨损而造成关键间隙超差,在键与槽、销与键之间的配合面熔覆钴基合金层,以提高耐磨性。方法分别通过激光堆焊、氩弧焊堆焊、氧乙炔堆焊等方法制备钴基合金熔覆层,研究熔覆层的显微组织结构、力学性能、耐腐性能等。结果激光堆焊熔覆层、氩弧焊堆焊熔覆层、氧乙炔堆焊熔覆层的枝晶臂直径测量值分别为15.28、20.09、21.91μm。激光堆焊熔覆层、氩弧焊堆焊熔覆层、氧乙炔堆焊熔覆层平均摩擦因数分别为0.183598、0.461085、0.625683。激光堆焊熔覆层、氩弧焊堆焊熔覆层、氧乙炔堆焊熔覆层平均磨损量分别为0.54、0.90、1.43 g。结论氩弧焊堆焊熔覆层的稀释率大于激光熔覆堆焊熔覆层、氧乙炔堆焊熔覆层的稀释率。EDS线扫结果表明,氩弧焊堆焊熔覆层的Fe含量随着层数的增加而阶梯性下降。在B含量为1200 mg/kg、Li含量为3.4 mg/kg的H3BO3和LiOH混合溶液中,氩弧焊堆焊熔覆层的耐蚀性最弱,激光堆焊熔覆层、氧乙炔堆焊熔覆层的耐蚀性相近。激光堆焊熔覆层综合力学性能最优,氩弧焊堆焊熔覆层的次之,氧乙炔堆焊熔覆层的最差。激光堆焊熔覆层的耐磨性能最优,氩弧焊堆焊熔覆层的次之,氧乙炔堆焊熔覆层的最差。通过激光熔覆技术可以获得优质的钴基合金熔覆层,有望确保堆内构件的限位精度,防止由于磨损而造成关键间隙超差。

The work aims to apply a cobalt-based alloy coating to mating surfaces of keys and slots,pins and keys to im-prove wear resistance,so as to ensure the dimensional accuracy of internal components and prevent excessive key clearances due to wear.Cobalt-based alloy clad layers were prepared through laser cladding,argon arc welding cladding,and oxyacetylene welding cladding to improve wear resistance.The microstructure,mechanical properties,and corrosion resistance of the clad layers were studied.The dendrite arm spacing measurements for laser cladding,argon arc welding cladding,and oxyacetylene welding cladding were 15.28,20.09,and 21.91μm,respectively.The average friction coefficients for laser cladding,argon arc welding cladding,and oxyacetylene welding cladding were 0.183598,0.461085,and 0.625683,respectively.The average wear amounts for laser cladding,argon arc welding cladding,and oxyacetylene welding cladding were 0.54,0.90,and 1.43,respec-tively.The dilution rate of argon arc welding is higher than that of laser cladding and oxyacetylene welding.Energy-dispersive X-ray spectroscopy(EDS)line scans indicate that the Fe content in clad layers produced by argon arc welding decreases with the increase in layers.In a mixed solution of H3BO3 with a B content of 1200 mg/kg and LiOH with an Li content of 3.4 mg/kg,the corrosion resistance of the argon arc welding clad layer is the weakest,while the laser cladding and oxyacetylene welding clad layers exhibit similar corrosion resistance.Laser cladding demonstrates the best comprehensive mechanical properties,fol-lowed by argon arc welding and then oxyacetylene welding.In terms of wear resistance,laser cladding performs the best,fol-lowed by argon arc welding and oxyacetylene welding.Laser cladding technology enables the production of high-quality co-balt-based alloy clad layers,potentially ensuring the dimensional accuracy of internal components and preventing excessive clearances induced by wear.