·252· 北京科技大学学报 1998年第3期 Kinetics of Calcium Ferrite Formation at Initial Stage of Reaction in CaO-Fe,O,Mixed Bed Guo Xingmin''Du Hegui产 1)Applied Science School.UST Beijing,Beijing 100083,China 2)School of Materials and Metallurgy,Northeastem University,Shenyang 110006,China ABSTRACT Kinetical model of calcium ferrite formation at initial stage of reaction in CaO-Fe,O,mixed bed was obtained by using terms of theory as follows: 1-kI-kBR)3-k(I+kBR)3=(2kM1p,月)·DAC. where,k=(p-P)/(pr-P),k:=(pa-p)/(p:-p),B=1 McPr/MPc.The results calculated by this model is identical very well with the experimental data,and the interdif. fusion coefficients of Cao in monocalcium ferrite were determined as 4.34x 10cm'/s and 2.32x 10-%cm'/s respectively at 1 160 and 1 190C. KEY WORDS mixed bed;formation;kinetics calcium ferrite 中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中休中中中中中 Kinetics of Carbide Layer Forming on the Surface of Steel in Molten Systems Shuhuan Wang Shengwen Wu Shantong Jin Metallurgy School,UST Beijing,Beijing 100083,China ABSTRACT A mathematical model of kinetics of carbide layer formed on the surface of steel in fused system was set up with the theory of non-stable diffusion mass transfer and regular solution sub-lattice.This model was analyzed and testified by the experiments in which the VC layers were formed on four kinds of steels as steel 45,4Cr5Mo- SiV1,T10,and Cr12MoV immersed in the V,O,-Na,O-B,O,fused system with the reducing agent of silicon.The results showed that there was a good agreement between the model and the experimental results the growth speed of carbide layer depended on the factors of carbon activity in substrate,treatment temperature ,kinds of carbides and its structure. KEY WORDS fused system;carbide;layer treatment;kinetics (Form:Journal of universit of Science and Technology beijing (English edition),1998,4(2):75) 中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中