微波场中高碳锰铁粉及固相脱碳物料的电磁性能

 碳酸钙粉热分解产生的CO2对高碳锰铁粉固相脱碳具有很好的脱碳作用,但脱碳过程中物料电磁性能的变化对微波加热的影响很大。 将高碳锰铁粉与碳酸钙粉按质量比1∶1均匀混合,在微波场中加热进行固相脱碳反应,脱碳温度分别为900、1000、1100、1200℃,且各保温脱碳60min。用矢量网络分析法测试试样的电磁性能。结果表明,高碳锰铁粉脱碳前后的电磁性能变化很大。脱碳物料的εr′在7.00~10.00范围内,εr″≈0.05。脱碳物料的μr′≈1.00,μr″≈0.00。温度为900和1200℃时,脱碳物料的电磁性能相近。高碳锰铁粉加热到1000和1100℃时,脱碳物料的tanδε和tanδμ最大,微波加热效果良好。     

Solid-phase Decarburization Kinetics of High-carbon Ferromanganese Powders by Microwave Heating

Solid-phase decarburization of high-carbon ferromanganese powders(HCFPs)was conducted using calcium carbonate powders(CCPs)as a decarburizer by microwave heating.Solid-phase decarburization kinetics was investigated by isothermal method.The results show that the HCFPs show excellent microwave absorption at a higher average heating rate of 80 ℃/min,while CCPs exhibit poor microwave absorption at a lower heating rate of 5-20℃/min;the heating characteristics are in-between when HCFPs and CCPs are mixed.The average heating rates of the mixture are 32.14,31.25,31.43,and 30.77 ℃/min when the mixture is heated up to 900,1 000,1 100,and 1 200℃,respectively.The good microwave absorption property of the mixed material lays the foundation for the solidphase decarburization of HCFPs containing CCPs.Solid-phase decarburization of HCFPs containing CCPs is a firstorder reaction by microwave heating.Apparent activation energy of solid-phase decarburization is 55.07kJ/mol,which is far less than that of ordinary carbon gasification reaction and that of solid-phase decarburization under the same decarburization condition by conventional heating.It indicates that microwave heating not only produces thermal effect,but also has non-thermal effect.     

Solid-Phase Decarburization of High-Carbon Ferromanganese Powders by Microwave Heating

The solid-phase decarburization of high-carbon ferromanganese powders (HCFPs) was investigated using calcium carbonate as the decarburizer by microwave heating and conventional heating methods to explore the differences of microwave heating and conventional heating. Experimental results show that HCFPs containing calcium carbonate were heated up to 900, 1000, 1100, and 1200 °C and held for 60 min for decarburization by microwave heating at decarburization ratios of 76. 69%, 82.90%, 84.11%, and 85.75%, respectively. These ratios arc higher than the decarburization ratios used for conventional heating under the same experimental conditions. The microwave heating can significantly improve decarburization ratio. This indicates the microwave heating field features a non-thermal effect, which in turn, visibly enhances the carbon diffusion ability of HCFPs. It also improves the kinetic conditions of solid-phase decarburization.     

Decarburization Thermodynamics of High-Carbon Ferromanganese Powders During Gas-Solid Fluidization Process

 Thermodynamic conditions of reactions between high-carbon ferromanganese powders and gas decarbonizers like O2, CO2 and water vapor were studied by thermodynamic calculation. In O2, CO2 and water vapor atmosphere, high-carbon ferromanganese powders were decarburized in a fluidized bed. When the temperature is respectively higher than 273, 1226 and 1312 K, the gas-solid decarburization reaction will occur between ferromanganese carbide on the surface of the high-carbon ferromanganese powders and different gas decarbonizers. Since metal manganese is easy to be oxidized by O2, CO2 or water vapor, the decarburization reaction will transfer into a solid-solid phase reaction of ferromanganese carbide and ferromanganese oxide, promoting external diffusion of carbon to achieve a further decarburization of high-carbon ferromanganese powders.     

电感耦合等离子发射光谱法(ICP-AES)测定高碳铬铁中的钛

介绍了电感耦合等离子发射光谱法测定高碳铬铁中Ti元素的试验方法。采用先加入磷酸和硝酸的混合酸溶解高碳铬铁,后用浓硝酸溶解溶液中碳化物等不溶物,冷却后,加入适量水溶解溶液中盐类,定容。用电感耦合等离子发射光谱测定溶液中Ti元素的光谱强度。配制标液建立标准曲线,使用标准曲线计算出样品中Ti的含量。该方法检测高碳铬铁中Ti的含量,准确度,精密度均符合生产检测的要求。     

微波消解ICP-AES测定高碳铬铁中锰

结合微波消解和ICP-AES方法特点,对应用微波消解-ICP-AES测定高碳铬铁中锰的条件进行了系统的研究,样品用硝酸和磷酸在微波消解仪中消解后,不分离基体直接在ICP-AES光谱仪上测定,方法的精密度、回收率均满足高碳铬铁样品的检验要求。试验证明此方法简单、快速、对仪器影响小,测定结果准确度高。     

微波冶炼高碳铬铁研究

为开发洁净、高效的高碳铬铁冶炼新工艺,对微波加热铬矿球团冶炼高碳铬铁进行试验研究,探明配碳量、配渣对铬回收率的影响。结果表明,微波加热铬矿球团100~120 min,可达到高碳铬铁冶炼所需的1 550~1 620 ℃,得到符合国标要求的高碳铬铁,铬回收率超过94%。当配碳系数为1.1,加入硅石使炉渣R=SiO2/(MgO+Al2O3)=0.55时,冶炼效果最好。当炉渣R值较低时,合金铬含量及回收率均明显下降,可以通过延长微波加热时间进行改善。     

高碳铬铁中Cr、P、Mn的联合测定

用过氧化钠熔融酸化的方法处理样品,用同一母液分别以过硫酸铵氧化容量法测定铬、钼蓝光度法测定磷,过硫酸铵银盐氧化光度法测定锰.通过控制测定的酸度,各元素线性良好,测得铬、磷、锰的相对标准偏差分别小于0.55%、4.75%、3.76%.该方法可缩短分析周期,精密度、准确度高.     

Microstructure of Solid Phase Reduction on Manganese Oxide Ore Fines Containing Coal by Microwave Heating

Microstructure of solid phase reduction on manganese oxide ore fines containing coal (MOOFCC) is one of important kinetics conditions of influencing microwave heating. On condition that an atomic molar ratio of rO∶rC in MOOFCC is 1∶1.06 as well as a molecular molar ratio of rSiO2∶rCaO is 1∶1.28,1 kg of MOOFCC is heated by microwave to reach 1000-1300℃ and hold different time respectively. Experiments show that the metal phase takes the iron-based metal compounds containing manganese as the main content. The manganese content of metal phase increases with the rise of temperature. The particle size of the metal phase is within the range from 0.01 to 0.05mm. MO2 phase in the stuff is entirely changed into MnO phase and the slag phase is mainly composed of wollastonite and manganese olivine. The stuff reduced is loose and massive as a whole and its porosity is from 30% to 45%. The low softening-melting property and the low density of the stuff impact,to some degree,the solid phase reduction of powder by microwave heating.     

少量碳粉对磁铁精矿微波加热的影响

为探求碳粉对磁铁精矿微波加热的影响,以微波加热（2．45GHz,IkW,加热时间20min）配碳（1wt％～3wt％）磁铁精矿实验为基础,进行了加热后试样的X射线衍射分析和过程的热力学计算。结果表明：微波加热后的试样中有Fe和FeO;加热过程中有碳粉与磁铁精矿之间的直接还原反应发生,它吸收大量热量,这是造成试样温度随配碳量增加而降低的主要原因。     

低碳钢固态相变过程的原位观察

利用共焦激光扫描显微镜（CSLM）原位观察了低碳钢升温及降温过程中的固态相变,直接观测出升温时低温铁素体（α）到奥氏体（γ）以及奥氏体（γ）到高温铁素体（δ）的相变温度,和降温时δ到γ以及γ到α的相变温度。结果表明,随着升温速率从75℃／min升至130℃／min,α—γ相变开始温度从961．6℃升至1014．0℃、γ→δ相变开始温度从1351℃升至1386．9℃;降温时随着降温速率的增大（70℃／min增至530℃／min）,γ—α相变开始温度从871．6℃降至858．4℃。在升温速率为130℃／min的情况下,随着升温最大值的提高（1300℃至1480℃）,γ—α相变温度降低,相变开始温度从895．2℃降至858．4℃。     

微波加热场中钢渣的还原脱磷行为

 在微波加热场条件下,对钢渣进行还原脱磷行为研究。结果表明：钢渣的吸波性能良好,不同组成钢渣在微波场中均具有较好的脱磷效果,脱磷率可达到51.35%～81.16%。碳当量和温度对脱磷的影响最显著,碳当量一般选择3～4倍较好。综合考虑影响脱磷效果的各种因素,确定微波处理钢渣脱磷的最佳工艺参数。     

微波场中含碳铬铁矿粉反应过程升温特性数值模拟

 对含碳铬铁矿粉在微波场中的升温特性作了分析。首先是分析加热谐振腔体的几何结构、耦合方式及物料的位置等来推测微波场分布，并通过实验进行了验证；进而分析了冶金化学反应的详细过程，结合含碳铬铁矿粉在微波场中的相关热及物理性质的变化，得出了在这个反应过程中物料的等效损耗因子；最后通过微波耗散功率与物料温度的关系的模拟计算，拟合出含碳铬铁矿粉的升温曲线。这种方法对于分析不同物料、不同配比、不同体积条件下在类似场结构下的微波冶金物料的化学反应过程中升温特性也是有效的。     

Reaction Process of Chromium Slag Reduced Industrial Waste in Solid Phase

M, a particular industrial waste, was selected to detoxify chromium slag at a high temperature. The carbon remaining in M reduced Cr (VI) of Na₂CrO₄ borne in the chromium slag to Cr (III) in the solid phase reaction, and its thermodynamics and kinetics were studied. The reduction process of Na₂CrO₄ by carbon produced CO, which was endothermic. Under the experimental condition, the apparent activation energy was 4. 41 kJ · mol⁻¹, the apparent order of reaction for Na₂ CrO₄ was equal to one, and the partial pressure of CO was only 0.22 Pa at 1 330 °C.     

Reaction Process of Chromium Slag Reduced by Industrial Waste in Solid Phase

 M, a particular industrial waste, was selected to detoxify chromium slag at a high temperature. The carbon remaining in M reduced Cr (Ⅵ) of Na2CrO4 borne in the chromium slag to Cr (Ⅲ) in the solid phase reaction, and its thermodynamics and kinetics were studied. The reduction process of Na2CrO4 by carbon produced CO, which was endothermic. Under the experimental condition, the apparent activation energy was 441 kJ·mol-1, the apparent order of reaction for Na2CrO4 was equal to one, and the partial pressure of CO was only 022 Pa at 1 330 ℃.     

微波加热与常规加热硅锰粉固相脱硅动力学比较

采用微波加热和常规加热对硅锰粉和巴西粉锰的脱硅反应进行了动力学行为研究,以巴西粉锰为脱硅剂,与硅锰粉中的硅发生氧化还原反应.微波加热和常规加热分别加热到不同温度并保温一定时间,测定产物中硅含量并计算固相脱硅反应的表观活化能.实验表明：单一和混合料均可在微波场中快速升温.随着温度的升高和保温时间的延长,两种加热方式脱硅率均随之提高,在相同实验条件下,微波加热的脱硅率和反应速率均高于常规加热,微波加热可以提高固相脱硅率;微波加热固相脱硅反应的限制性环节为扩散环节,其表观活化能为102.93 kJ·mol^-1,常规加热脱硅反应的表观活化能为180 kJ·mol^-1,说明微波加热能改善固相脱硅的动力学条件,提高固相脱硅反应速率,降低脱硅反应的活化能.     

Investigation of the Effect of Deformation on γ‐α Phase Transformation Kinetics in Hot‐Rolled Dual Phase Steel by Phase Field Approach

Dual phase steels, consisting of hard martensite particles in a ductile ferritic matrix, offer high strength and deformability at the same time. Additionally, they are cost effective by a dilute alloying concept. In industrial production, two manufacturing concepts have been implemented: intercritical annealing of cold rolled sheet, or hot rolling. The current work has investigated the effect of deformation on the γ‐α phase transformation kinetics in the dual phase steel production using the hot rolling scheme. The pancaked austenite grains containing denser nucleation sites have a strong influence on the ferrite transformation kinetics. In addition, the multiplication of dislocations which results in the increase in elastic strain energy and dislocation core energy contributes to some acceleration in ferrite growth kinetics. A modelling approach for the γ‐α phase transformation kinetics in dual phase steels has been developed employing the phase field theory. The nucleation behaviour, i.e. the number and size of nuclei developed after an elapsed time as well as their nucleation sites which were evaluated from microstructure analysis, and the increase in the driving force of grain growth were integrated into this model.     

一水硬铝石矿-氢氧化钠体系微波焙烧相变规律

以饱和氢氧化钠溶液为添加剂,利用微波加热对一水硬铝石矿进行焙烧处理.考察微波焙烧温度和氢氧化钠添加量对一水硬铝石矿-氢氧化钠体系相变规律的影响,并对微波加热和常规加热得出的焙烧产物做物相结构的比较.利用X射线衍射分析和扫描电子显微镜技术对熟料的物相结构和微观形貌进行分析.结果表明微波加热促进氢氧化钠快速并充分的与一水硬铝石矿反应.与常规加热相比,微波加热在更低的温度下能生成更多铝酸钠物相.微波加热后的熟料疏松多孔,有利于后续溶出处理.