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通过在铸造涂料中引入(5~40)%FeS,利用FeS的蠕化衰退作用,在蠕墨铸铁局部表层制备1~5 mm灰铸铁。综合运用OM,EPMA和激光热导仪分析了涂料中FeS含量对铸件石墨形态分布规律的影响机理及其对铸件不同部位的导热系数的影响规律。结果表明:随着Fe S含量增大,铸件表层灰铸铁的厚度先逐渐增大直至平衡;从铸件表面到内部,石墨形态由A型逐渐转变为D型,最后到蠕虫状石墨;且残留的S含量逐渐降低,残留的Mg含量逐渐升高,Mg与S形成化合物,降低了铸件表面的残余Mg含量,发生蠕化衰退,形成灰铸铁。从铸件表面到内部相同温度下的导热性能逐渐降低。
Through the introduction of (5 ~ 40)% FeS into the foundry coatings and the use of FeS as the decaying effect, 1 ~ 5 mm gray cast iron was prepared on the surface of compacted graphite cast iron. The influence mechanism of FeS content in coatings on the distribution of graphite morphology and its influence on the thermal conductivity of different parts of castings were analyzed by OM, EPMA and laser thermal conductivity instrument. The results show that with the increase of Fe S content, the thickness of gray cast iron on the surface of castings first increases until the equilibrium is reached. From the surface of the castings to the inside, the morphology of graphite gradually changes from type A to type D and finally to vermicular graphite. S content gradually decreased, the residual Mg content gradually increased, Mg and S compounds, reducing the residual Mg content of the casting surface, the occurrence of vermicular decay, the formation of gray cast iron. The thermal conductivity at the same temperature from the casting surface to the interior gradually decreases.