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烟煤相对氧化度测定方法解析
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作者 隋艳 富坤 《煤质技术》 2020年第3期73-76,81,共5页
烟煤相对氧化度是对冶金用煤的选择具有指导意义的指标,准确测定烟煤的氧化度对炼焦工业具有实际意义。针对腐植酸的氢氧化钠碱溶液一次抽提测定方法,通过选取不同的烟煤样品及对比不同试验条件,验证样品粒度、润湿剂的种类和用量等对... 烟煤相对氧化度是对冶金用煤的选择具有指导意义的指标,准确测定烟煤的氧化度对炼焦工业具有实际意义。针对腐植酸的氢氧化钠碱溶液一次抽提测定方法,通过选取不同的烟煤样品及对比不同试验条件,验证样品粒度、润湿剂的种类和用量等对测定结果的准确性的影响,对烟煤相对氧化度测定方法进行了解析。试验研究结果表明:试样粒度为0.2 mm、采用适量辛基苯氧基聚乙氧基乙醇非离子型表面活性剂或十二烷基硫酸钠溶液作为润湿剂并严格控制加热速率、加热时间和滤液体积的条件下可在碱抽提反应中获得最佳腐植物酸产率,以其透光率指标表征烟煤的相对氧化度。 展开更多
关键词 烟煤 相对氧化度 测定方法 润湿剂 透光率 腐植酸产率 碱抽提溶液
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Effect of relative density on cyclic oxidation resistance properties of MoSi_2
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作者 颜建辉 李益民 张厚安 《Journal of Central South University of Technology》 2008年第3期301-304,共4页
MoSi2 powders were fabricated respectively by mechanical alloying technique and sintering at different temperatures to prepare materials with different relative densities. The relative oxidation behavior of all MoSi2 ... MoSi2 powders were fabricated respectively by mechanical alloying technique and sintering at different temperatures to prepare materials with different relative densities. The relative oxidation behavior of all MoSi2 materials at 1 473 K was investigated by TGA,SEM and XRD. The results show that the "pesting" is not found in all materials after being oxidized for 480 h. The density has no essential relation to the "pesting". The oxidation curve of specimens with lower density shows two-step oxidation kinetics. Both the first stage (0-1 h) and the second stage (1-480 h) nearly obey linear kinetics,but the oxidation rates are obviously different. The oxidation kinetics of MoSi2 with higher relative density nearly follows parabolic law. The mass gains of MoSi2 with the lowest relative density (78.6%) and the highest relative density (94.8%) are increased by 10.390 and 0.135 mg/cm2,respectively. The oxide scale of materials with lower densities is non-protective and makes the oxygen diffusion easy. A dense scale in the material with higher density is formed,which acts as a diffusion barrier to the oxygen atoms to penetrate into the matrix,showing much better high temperature oxidation resistance. The phases distribution of oxidation scale from the outside to the inside is SiO2→Mo5Si3→MoSi2. 展开更多
关键词 MOSI2 relative density DIFFUSION oxidation resistance
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