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本文应用金相显微镜、扫描电镜,X-射线衍射仪研究了在900℃,latm 条件下片状石墨铸铁(3.59%C,2.5%Si,0.22%Cr,0.20%Mo)的氧化膜以及内部氧化区的结构,结果表明:氧化膜大致分为两层:外层是由纯铁的氧化物组成,内层是由铁的氧化物与 Si,Cr 合金元素的氧化物组成.外层又可分为三层,山外向内依次是 Fe_2O_3,Fe_3O_4,Feo,外层的生长机理与纯铁的氧化相同.内层与内部氧化区又存在特殊的氧化区域.这个特殊的氧化区是由于石墨与 O_2的直接作用,产生气体向外逸出,留下的空腔被金属氧化产物充填而产生的.合金元素Si,Cr 在该区的富集并不是山于合金元素在石墨片周围的偏析,而是由于 O_2沿石墨片与基体的缝隙侵入,石墨片边缘的合金元素被优先氧化的缘故.
In this paper, the oxide films of flake graphite cast iron (3.59% C, 2.5% Si, 0.22% Cr, 0.20% Mo) and internal oxidation at 900 ℃ and latm were studied by metallographic microscope, scanning electron microscope and X- The results show that the oxide film is roughly divided into two layers: the outer layer is composed of pure iron oxide, the inner layer is composed of iron oxide and oxides of Si and Cr alloying elements, and the outer layer can be divided The outer layer is composed of Fe_2O_3, Fe_3O_4 and Feo, and the growth mechanism of the outer layer is the same as the oxidation of pure iron. There are also special oxidation zones in the inner and inner oxidation zones. This special oxidation zone is due to the interaction between graphite and O_2 The direct action of the gas, resulting in the gas to escape outward, leaving the cavity filled with metal oxide products generated by the alloy elements Si, Cr enrichment in the area is not the mountain alloying elements around the graphite sheet segregation, and Is due to O_2 along the gap between the graphite sheet and the matrix intrusion, alloying elements at the edge of the graphite sheet is preferentially oxidized.