铁碳合金薄带气—固反应脱碳动力学分析

发布时间：2018-06-15 18:50

本文选题：气—固反应 + 脱碳　；参考：《华北理工大学》2016年硕士论文

【摘要】：本研究在Ar-H_2-H_2O弱氧化气氛条件下,以高碳铁碳合金薄带的脱碳反应作为研究对象,进行气—固脱碳反应动力学研究,重点研究内容包括脱碳速率的影响因素、薄带内部碳浓度的分布、脱碳反应限制性环节等动力学分析。提出了改善脱碳动力学条件、提高脱碳效果的方法。实验以初始碳含量、厚度、脱碳温度、时间和气氛条件为变量,以单因素法对脱碳反应进行研究。脱碳反应采用初始碳含量分别为4.2%和3.2%铁碳合金薄带为实验原料,薄带厚度分别为0.6mm、1.0mm、1.5mm和2mm,脱碳温度为1293~1413K,脱碳时间为10~80min。研究结果表明铁碳合金薄带气—固脱碳反应为表观一级反应,脱碳反应活化能144.9KJ/mol,与奥氏体相区碳的扩散活化能理论值Q=140KJ/mol基本相同。实验结果证明碳从薄带内部向反应界面的扩散是限制性环节。根据升高温度提高脱碳速率的结论提出了分段加热脱碳法,采用分段加热法初始碳含量为4.15%的2mm铁碳合金薄带的碳含量在70min内可以由原恒温法的0.98脱除到0.28%。实验通过单因素法分析影响脱碳速率的因素,得出了碳含量定量关系的函数表达式。在不同的实验条件下,脱石墨层深度均与时间的二分之一次方呈良好的线性关系,y=Ct~(1/2)。薄带厚度越厚,温度越高,脱石墨层向中心推移地越快。通过计算得到1293K温度下表观扩散系数D=3.4~3.5×10~(-7)cm~2/s,与扩散系数经验值基本一致,由此可以证明在整个脱碳过程中脱碳反应的限制性环节是碳在奥氏体相区的扩散。
[Abstract]:In this study, the kinetics of gas-solid decarburization reaction was studied under the condition of Ar-H2-H2O weak oxidation atmosphere and the decarburization reaction of high-carbon Fe-C alloy strip was studied. The main contents of the study included the factors affecting the decarburization rate. The distribution of carbon concentration in the thin strip and the limiting link of decarbonization reaction were analyzed. The methods to improve the kinetics of decarbonization and to improve the decarbonization effect are put forward. The initial carbon content, thickness, decarburization temperature, time and atmosphere conditions were taken as variables in the experiment, and the decarburization reaction was studied by single factor method. The initial carbon content of 4. 2% and 3. 2% Fe-C alloy ribbons were used as raw materials for the decarburization reaction. The thickness of the ribbons was 0.6 mm ~ 1.0mm ~ (-1) mm ~ (1.5) mm and 2 mm respectively. The decarburization temperature was 1293 ~ (-1) K and the decarburization time was 10 ~ 80 min. The results show that the gas-solid decarbonization reaction of Fe-C alloy is an apparent first-order reaction, and the activation energy of the decarbonization reaction is 144.9 KJ / mol, which is basically the same as the theoretical value of diffusion activation energy Q _ (140) KJ / mol in the austenitic phase region. The experimental results show that the diffusion of carbon from the inner band to the reaction interface is a restrictive link. According to the conclusion of increasing the decarburization rate by increasing the temperature, a new method of decarburization by subsection heating is proposed. The carbon content of 2mm ferrocarbon alloy strip with 4.15% initial carbon content can be removed from 0.98 to 0.28 in 70min. The factors influencing decarbonization rate were analyzed by single factor method, and the functional expression of quantitative relationship of carbon content was obtained. Under different experimental conditions, there is a good linear relationship between the depth of the delaminated layer and the 1/2 power of time. The thicker the strip thickness and the higher the temperature, the faster the degraphite layer moves toward the center. At 1293K, the apparent diffusion coefficient D3. 4 ~ 3. 5 脳 10 ~ 10 ~ (-7) cm ~ (-1) / s is in good agreement with the empirical value of the diffusion coefficient. It is proved that the limiting part of the decarbonization reaction is the diffusion of carbon in the austenitic phase region during the whole decarbonization process.
【学位授予单位】：华北理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG141

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