摘要
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.
Studies the structure of the oxide scale and internal oxidation zone formed in flaky graphite cast iron(3.59%C,2.5%Si,0.22%Cr,0.20%Mo)heated at 900℃ in 1 atm with microscope,electron probe and X-ray diffraction microanalyzer.The results obtained show.the oxide scale is divided roughly into two lay- ers;the outer layer is compossed of pure iron oxides,and the inner layer,in which the oxides of alloy elements Si and Cr are detected besides the iron oxides.The former is classified in detail into three layers:Fe_2O_3,Fe_3O_4 and FeO,and grows in the same machanism as in the oxidation of pure iron.The latter and the internal oxidation zone include the special oxidation area which is formed by filling up the void spaces caused by escaping out of gaseous oxidation products of graphite from the system with metal oxides.The concentration of Si and Cr in this area is higher than in the other parts in this layer,not because of Si and Cr segregation in the vicinity of graphite,but became that the alloy dements Si and Cr in the vicinity of graphite are oxidized preferentially where gaseous oxygen diffuses through the channel between flaky graphite and matrix.
出处
《大连铁道学院学报》
1992年第2期71-76,共6页
Journal of Dalian Railway Institute
基金
大连市科委重点科研课题:87054.
关键词
铬钼合金
合金灰铸铁
氧化膜构造
Cr-Mo alloyed flaky graphite cast iron
structure of oxide scale
