微波加热喷动流化床高碳铬铁粉固相脱碳显微结构研究
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摘要
以空气作为流化气体,在微波加热喷动流化床中对高碳铬铁粉进行固相脱碳,研究不同温度和保温时间条件下对物料显微结构的变化。试验表明,加热温度800℃、保温1h,高碳铬铁中粗大的(Cr,Fe)7C3开始分解,并产生少量(Cr,Fe)23C6-(CrFe),呈不规则星点状分布在(Cr,Fe)7C3晶粒内部;随着加热温度的提高和保温时间的延长,星点状的(Cr,Fe)23C6-(CrFe)逐渐变大,形成类蜂窝状结构;加热温度1 000℃、保温3h,粗大的(Cr,Fe)7C3晶体分解形成网络状结构。在微波加热喷动流态化条件下,高碳铬铁粉固相脱碳效果明显,反应均匀,能够有效抑制粘接失流现象。
The microstructure of high-carbon ferrochrome powders after solid-state decarburization in the microwave spouted fluidized bed is not only relative to rate of decarbonization,but also to the microwave field.Thus,microwave may affect the extent of defluidization of material.In the experiment,air was used as spouted fluidized decarbonization gas.The high-carbon ferrochrome powders were heated by microwave spouted fluidized bed for solid-state decarbonization.The change of microstructure of high-carbon ferrochrome powders was studied in the different decarbonization temperature and decarbonization holding time.The test result shows that the thick(Cr,Fe)7C3in high-carbon ferrochrome begins to decompose at 800 ℃for 1h.A small quantity of star-like(Cr,Fe)23C6-(CrFe)forms uniformly in the grain of(Cr,Fe)7C3.With the increase of the heating temperature and holding time,the star-like(Cr,Fe)23C6-(CrFe)grain becomes larger and changes into honeycomb structure.The thick(Cr,Fe)7C3decomposes into net structure at1000 ℃for 3h.With the condition of microwave heating and spouted fluidization,the solid-state decarburization of high-carbon ferrochrome powders has some remarkable advantanges,such as homogeneous reaction and low degree of oxidation.In addition,defluidization is effectively restrained.
The microstructure of high-carbon ferrochrome powders after solid-state decarburization in the microwave spouted fluidized bed is not only relative to rate of decarbonization,but also to the microwave field.Thus,microwave may affect the extent of defluidization of material.In the experiment,air was used as spouted fluidized decarbonization gas.The high-carbon ferrochrome powders were heated by microwave spouted fluidized bed for solid-state decarbonization.The change of microstructure of high-carbon ferrochrome powders was studied in the different decarbonization temperature and decarbonization holding time.The test result shows that the thick(Cr,Fe)7C3in high-carbon ferrochrome begins to decompose at 800 ℃for 1h.A small quantity of star-like(Cr,Fe)23C6-(CrFe)forms uniformly in the grain of(Cr,Fe)7C3.With the increase of the heating temperature and holding time,the star-like(Cr,Fe)23C6-(CrFe)grain becomes larger and changes into honeycomb structure.The thick(Cr,Fe)7C3decomposes into net structure at1000 ℃for 3h.With the condition of microwave heating and spouted fluidization,the solid-state decarburization of high-carbon ferrochrome powders has some remarkable advantanges,such as homogeneous reaction and low degree of oxidation.In addition,defluidization is effectively restrained.
引文
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[3]唐思文,彭成章,颜建辉.高能球磨对高碳铬铁真空固相脱碳的影响[J].热加工工艺,2012,5(16):10-16.
[4]梁敏,陈津,林万明,等.高碳锰铁粉固相脱碳热力学研究[J].铁合金,2009,5(1):14-19.
[5]Moshtaghioun B M,Poyato R,Cumbrera F L,et al.Rapid carbothermic synthesis of silicon carbide nano powders by using microwave heating[J].Journal of the European Ceramic Society,2012,32(8):1787-1789.
[6]Crane C A,Pantoya M L,Week B L,et al.The effects of particle size on microwave heating of metal and metal oxide powders[J].Powder Technology,2014,256(4):113-118.
[7]王龙,陈津,郝赳赳,等.微波加热内配碳酸钙高碳铬铁粉脱碳物料的物相结构[J].过程工程学报,2013,13(3):415-421.
[8]赵杏新,刘伟民,罗惕乾,等.喷动床研究进展[J].农业机械学报,2006,37(7):189-193.
[9]Chen Y,Zhong W Q,Jin B S.Experiment study of spout characteristics of a cone-Base cylindrical spouted bed[J].Journal of Engineering Thermophysics,2012,33(3):433-437.
[10]陈津,郭丽娜,郝赳赳,等.微波加热喷动流化床冶金反应器设计与分析[J].太原理工大学学报,2014,45(1):10-14.
[11]陈丽梅,金燕.出口结构对循环流化床锅炉床内轴向密度的影响[J].太原理工大学学报,2006,(S2):140-142.
[12]Vinayak S Sutkar,Niels G Deen,Kuipers J AM.Spout fluidized beds:Recent advances in experimental and numerical studies[J].Chemical Engineering Science,2013,86(21):124-130.
[13]畅永锋,翟秀静,符岩,等.微波加热还原含碳红土矿的研究[J].矿冶工程,2008,28(5):76-81.
[14]Shi A R,Jia Y F.Mechanism of enhanced diffusion in microwave solid state reaction[J].Journal of Qingdao University,1998,11(1):64-67.
[15]郝赳赳,陈津,韩培德,等.微波场中高碳给铁粉固相脱碳机理研究[J].太原理工大学学报,2014,45(5):571-575.
[16]王建军,李兆峰.铁矿粉流态化还原防粘机理研究[J].过程工程学报,2010,10(1):31-36.
[17]Hideya N,Naoki D,Hirohisa T.Numerical investigation on the solid flow pattern in bubbling gas-solid fluidized beds:Effects of particle size and time averaging[J].Chemical Engineering Science,2014,116(6):725-730.
[18]赵志星,金山同.熔渣法碳化铬涂层的抗氧化性能研究[J].金属热处理,2002,27(6):18-23.