M.H.Khedr
材料科学技术（英文）
CO2 is a major component of the greenhouse gases, which causes the global warming. To reduce CO2 gas, high activity nanosized Ni+2 substituted Fe2TiO5 samples were synthesized by conventional ceramic method. The effect of the composition of the synthesized ferrite on the H2-reduction and CO2-catalytic decomposition was investigated. Fe2TiO5 (iron titanate) phase that has a nanocrystallite size of ~80 nm is formed as a result of heating Fe2O3 and TiO2 while the addition of NiO leads to the formation of new phases (~80 nm) NiTiO3 and NiFe2O4, but the mixed solid of NiO and Fe2O3 results in the formation of NiFe2O4 only. Samples with Ni+2=0 shows the lowest reduction extent (20%); as the extent of Ni+2 increases, the extent of reduction increases. The increase in the reduction percent is attributed to the presence of NiTiO3 and NiFe2O4 phases, which are more reducible phases than Fe2TiO5. The CO2 decomposition reactions were monitored by thermogravimetric analysis (TGA) experiments. The oxidation of the H2-reduced Ni+2 substituted Fe2TiO5 at 500℃ was investigated. As Ni+2 increases, the rate of reoxidation increases. Samples with the highest reduction extents gave the highest reoxidation extent, which is attributed to the highly porous nature and deficiency in oxygen due to the presence of metallic Fe, Ni and/or FeNi alloy. X-ray diffraction (XRD) and transmission electron microscopy (TEM) of oxidized samples show also the presence of carbon in the sample containing Ni+2>0, which appears in the form of nanotubes (25 nm).
关键词:
Nanocrystallite
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null
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null
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null
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null
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null
M. Bahgat
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null
材料科学技术（英文）
Iron carbides are very promising metallurgical products and can be used for steelmaking process, where it plays as an alternative raw material with significant economic advantages. Also it has many other applications, e.g. catalysts, magnets, sensors. The present review investigates the different properties and uses of the iron carbides. The commercial production and the different varieties for the iron carbides synthesis (gaseous carburization, mechanochemical synthesis, laser pyrolysis, plasma pyrolysis, chemical vapor deposition and ion implantation) were reviewed. Also the effect of different factors on the carburization process like gas composition, raw material, temperature, reaction time, catalyst presence and sulfur addition was indicated.
关键词:
Iron carbides
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null
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null
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null
吴树昌
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温国栋
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钟炳伟
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张炳森
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谷献模
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王宁
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苏党生
催化学报
doi:10.1016/S1872-2067(14)60102-9|
本文对碳材料(主要是碳纳米管)催化硝基苯的还原反应进行了系统研究。通过热重分析、程序升温脱附、透射电子显微镜、物理吸附以及拉曼光谱等表征，发现碳材料表面的含氧官能团在反应中起着重要的作用，而比表面、孔结构、形貌、结构缺陷以及可能存在的铁杂质对反应没有显著影响。羰基的作用非常重要，但是羧基和酸酐对反应不利。除此之外，材料的π电子体系也很关键，因为它可以传递电子，并且利于硝基苯的吸附。硝基苯还原按照直接路径进行，反应过程中生成的中间体亚硝基苯可以迅速转化为苯胺。
关键词:
碳材料
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氧官能团
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活性位
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硝基苯
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还原
孙映
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封亚晖
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陈法涛
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李秋菊
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洪新
上海金属
利用碳还原-磁选工艺回收低品位红土镍矿中的铁和镍.在对矿物成分、物相分析的基础之上,考察还原反应温度、配碳比(C/O)、助熔剂的添加量(CaO％)和还原时间等因素对Fe、Ni回收的影响,结果表明,还原反应温度1 375℃、配碳比(C/O)0.8、助熔剂的添加量(CaO％) 12％、还原时间300 min的条件下,低品位红土镍矿中镍和铁的回收率分别为99.47％和97.54％,同时尾矿中Ni、Cr含量低于0.04％.
关键词:
红土镍矿
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还原
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磁选
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铁镍合金
李德刚
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刘泽田
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董瑞峰
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王国栋
上海金属
详细分析了板坯温度、轧机上下工作辊直径差及转速差、单道次压下率等因素对中厚板轧件头部弯曲的影响.同时综合考虑现场实际生产时的各种影响头部弯曲的因素,从优化单道次压下率、优化咬入长度及其咬入速度等方面提出了轧件头部弯曲控制方法,实际生产中有效地控制了中厚板头部弯曲现象,效果明显.
关键词:
轧制
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中厚板
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头部弯曲
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压下率
Ali Saidi
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Kamran Azari
材料科学技术（英文）
Industrial application of microwave, as a heating source for material processing, was reviewed. The feasibility of carbothermic reduction of zinc oxide concentrate, as well as the effect of operating parameters was investigated, using a home style microwave oven at 2.45 GHz. Zinc oxide concentrate does not effectively absorb microwave energy, while any source of carbon, which is used as the reduction agent, absorbs microwave energy very well. In this respect coke breeze was found to be the best, and thus, coke was used both as the reducing agent and the absorbent of microwave energy. It was also found that any increase in the carbon content and size, increases the reduction rate. Increasing the microwave power and the size of the sample could also increase the reduction rate. Further investigation shows that when zinc oxide is exposed to the microwave for some time, the rate of the reduction by conventional method increases.
关键词:
Microwave
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null
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null
杨真真
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郑庆彬
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邱汉迅
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李静
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杨俊和
新型炭材料
doi:10.1016/S1872_5805(15)60174_3
以CaCl2作为催化剂、NaBH4为还原剂,还原氧化石墨烯。还原反应能在室温下进行,并以去离子水作为唯一的溶剂,此法是一种低能耗、环保并简易的方法。通过红外光谱、紫外光谱、X射线光电子能谱、表面电阻测量手段研究CaCl2添加量对氧化石墨烯还原程度的影响。采用透射电子显微镜和原子力显微镜观察氧化石墨烯和还原氧化石墨烯的形貌。结果表明,以氯化钙作为催化剂还原氧化石墨烯,能更有效地去除氧化石墨烯表面的含氧官能团,提高还原氧化石墨烯的导电性。当CaCl2添加浓度达到50 mmol/L时,还原氧化石墨烯C/O比达到5.38,表面电阻达到18.6 kΩ/sq。
关键词:
氧化石墨烯
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还原
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催化剂
