Research On Oxidation Resistance Of High Chromium Cast Iron With Different RE Adding At High-temperature

This article through the practical analysis of the conditions and the failure reason about the grate-bar, determined by high chromium cast iron as material,with an optimal service life and good performance-to-price ratio. In order to further improving high temperature properties of high chromium cast iron, joined the Y-RE micro-alloying processing. According to the comparing analysis under different oxidation-temperature and time, different RE adding of high chromium cast iron, understood the phase-composition of the surface oxidation film, and acquired the best RE addition for the composition of high chromium cast iron:(1) Through the phase-composition analysis for the oxidation film of high chromium cast iron oxide, get the iron-oxidation film (FeO,Fe3O4,Fe2O3,etc) and chromium oxidation film (Cr2O3) of the phase-composition for the oxidation film.(2) The oxidation weight as per unit area follows a parabolic rule changing over time; content of RE from 0 to 0.3wt.%, with the content increasing, oxidation resistance of high chromium cast iron at high-temperature gradually improve; but when the content exceeds 0.3wt.%, oxidation resistance of high chromium cast iron reduces.Through the above analysis on oxidation resistance of high chromium cast iron with RE adding at high-temperature obtained:(1) Nucleation-core At the beginning of oxidation,RE elements priority the phase-oxidation on the alloy surface, which have the same lattice type with Cr2O3 and Fe2O3, thus oxidation particle of RE in the surface alloy is formed as nucleation core of (Fe,Cr,Y)2O3 film, promotting the formation of protective oxidation film. Once the protective oxidation film formed, which slew the oxidation, which reduces the chromium and iron to lose.(2) Pinning-effective In the growth-processing of oxidation, because of RE elements addition, there will be the bar and block oxidation particle of RE in the oxidation film/ matrix interface, and further in the matrix along with the grain boundaries or transqranular,and and substratting oxidation film with matrix, thus the forming oxidation film fall off easilly and has a good protective.