微波加热浸出初级富钛料非等温动力学及吸波特性

研究微波加热浸出初级富钛料非等温动力学,测定浸出体系的温度和压力曲线及浸出前后混合液体的吸波特性.动力学研究以铁浸出率为衡量指标,在本研究条件下推导出微波浸出初级富钛料动力学表观总速率方程.温度和压力曲线表明,浸出体系温度和压力的提高都有利于提高铁的浸出率;浸出前后混合液体吸波特性表明,15%盐酸浸出液和经20%盐酸浸出后的混合液都存在吸波特性的突变.     

高岭石脱水反应的非等温热重法研究

在系统分析非等温固相反应特点的基础上,建立了非等温脱水反应速率方程.采用非等温热重法、通过计算机辅助计算,对高岭石脱水反应动力学规律进行了研究.结果表明:由于高岭石晶体结构中内、外羟基脱除的顺序不同,其脱水反应机制在反应分数(α)为0.7左右时发生改变.在反应前期(0＜α＜0.7)时,脱水反应遵循二维扩散控制规律,脱水反应表观活化能为159.682 kJ/mol、表观频率因子为1.007×10 10/min.     

Non-isothermal decomposition kinetics and lifetime ofTb2(O-MBA)6(PHEN)2

The thermal decomposition of Tb2(O-MBA)6(PHEN)2 (O-MBA: o-methylbenzoate; PHEN: 1,10-phenanthroline)and its kinetics were studied under the non-isothermal condition by thermogravimetry-derivafive thermogravimetry (TG-DTG) techniques. Kinetic parameters were obtained from analysis of TG-DTG curves by the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method. The most probable mechanism function was suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as dα/dt = Aexp(-E/RT) @ 3(1 - α)2/3. The lifetime equation at mass loss of 10% was deduced as lnτ= -28.7429 + 19797.795/T by isothermal thermogravimetric analysis.     

Non-isothermal decomposition kinetics and lifetime of Tb2(0-MBA)6(PHEN)2

The thermal decomposition of Tb2(O-MBA)6(PHEN)2 (O-MBA: o-methylbenzoate; PHEN: 1,10-phenanthroline) and its kinetics were studied under the non-isothermal condition by thermogravimetry-derivative thermogravimetry (TG-DTG) techniques. Kinetic parameters were obtained from analysis of TG-DTG curves by the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method. The most probable mechanism function was suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as dcddt = Aexp(-E/RT) 3(1 - α)2/3 The lifetime equation at mass loss of 10% was deduced as lnr= -28.7429 + 19797.795/Tby isothermal thermogravimetric analysis.     

Non-isothermal kinetics of the first-stage decomposition reaction of the complex of samarium p-methoxybenzoate with 1,10-phenanthroline

The complex of [Sm(p-MOBA)3phen]2 (p-MOBA, p-methoxybenzoate; phen, 1,10-phenanthroline) was pre- pared and characterized by elemental analysis, IR, and UV spectroscopy. The thermal decomposition of the [Sm(p-MOBA)3phen]2 complex and its kinetics were studied under a static air atmosphere by TG-DTG methods. The in- termediate and residue for each decomposition stage were identified from the TG curve. The kinetic parameters and mecha- nisms of the first decomposition stage were obtained from the analysis of the TG-DTG curves by a new method of process- ing the data of thermal analysis kinetics. The lifetime equation at a mass loss of 10% was deduced as lnτ = – 30.6795 21034.56/T by isothermal thermogravimetric analysis.     

Preparation and microwave absorption properties of FeNi/graphite nanocomposites

FeNi/graphite nanocomposites were prepared by reducing FeCl3-NiCl2-GlCs in H2. The elemental composition, structure, magnetic and microwave absorption of FeNi/graphite nanocomposites were investigated using X-ray diffraction, energy dispersive spectra, hysteresis loop and electromagnetic parameter analysis. The results show that with the increase of the reduced temperature, the number and size of particles of FeNi increases, and the FeNi/graphite nanocomposites changes to soft magnetism. FeNi/graphite nanocomposites bear microwave absorption properties. With the increase of the thickness of the sample, the matching frequency tends to shift to the low frequency region, and theoretical reflection loss becomes less at the matching frequency. Microwave absorption property in the low frequency region of FeNi/graphite nanocomposites prepared at 600 ℃ （FeNi/C600） is the best. When the thickness is 2 ram, the maximum theoretical reflection loss of FeNi/C600 is -4.3 dB and the matching frequency is 3.5 GHz.     

熔盐电解制备低成本Ti12LC钛合金的研究

利用覆盖渣技术在非真空条件下成功制备出了直径为3 mm的Zr55Ni5Al10Cu30块体非晶合金.采用差示扫描量热法(DSC),将Johnson-Mehl-Avrami理论拓展应用于非晶合金的非等温晶化过程研究.结果表明,Zr55Ni5Al10Cu30块体非晶合金的连续升温晶化过程Avrami指数及形核率随升温速率的升高而呈下降趋势,同时随晶化过程进行呈先增加后减小的规律.Avrami指数最大值出现在晶化体积分数0.3～0.4之间,在低升温速率下Zr55Ni5Al10Cu30块体非晶合金部分晶化过程出现三维形核界面控制长大的形式.     

钛精矿的微波干燥特性及动力学

研究微波功率及物料量对钛精矿微波干燥的含水率、脱水速率、水分比等干燥特性的影响.实验微波功率范围为119～700 W,物料量为5～25 g.不同的干燥条件下干燥过程均延续2～8 min.研究发现微波功率密度对含水率和干燥速率的影响较大,所有干燥过程都有一个明显的特征,即在初始阶段有加速干燥峰.固定物料量为25 g和微波...     

Al-Si过共晶合金中初生硅的溶解动力学

以扩散为模型,并考虑界面反应对初生相溶解过程的影响,建立了初生相在过热９熔体中的溶解动力学模型。同时以Ａｌ－１８％Ｓｉ（质量分数）合金为对象,在１１００℃过热情况下,对该模型进行了验证。结果表明;该模型基本上能反应该条件下初生硅的溶解特性。     

A novel microwave absorption and dielectric spectrum detection technology in photoelectron dynamic study for solar cells

The photoelectron property is directly related to the light-energy conversion efficiency of solar cells. In this paper, the photoelectron dynamic of semiconductor was analyzed. The diffusion of electrons has influence on the dielectric function of the solar cell material. And the amplitude variance of the imaginary andreal part of the dielectric function is in direct proportion to the dynamic process of free and shallow-trapped electrons. Based on the untouched detection technique, the method is present to detect the amplitude change of the microwave signal which is passing through the material whose dielectric function changes after exposure. A35GHz oscillator was used as a microwave source. The absorptionand dispersion microwave signals, which contain the dynamic information of free and shallow-trapped electron signal, are split respectively with phase-sensitive instrument. The photoelectron character of n-type Si(100) thin film was investigated by the novel equipment, and the lifetime of different kinds of electronswith the resolution of 1 ns was obtained. The equipment can be directly used inthe study of the optoelectronic conversion mechanism of solar cells.     

Ni-Al-W活性材料的界面扩散动力学

采用粉末冶金法制备Ni-Al-W活性材料Ni37.5 Al42.5 W20,研究了材料中Ni-Al、Al-W、Ni-W 3种不同界面处的扩散动力学.结果表明:在400℃保温不同时间下该材料表观激活能变化不大;扩散层厚度Δx随时间t的增加而增加,且lnΔx与lnt呈线性关系,在3种不同界面处只发生了扩散而未产生金属间化合...     

非晶合金的晶化动力学与初生相的内在联系

通过差示扫描量热法(DSC)研究了Zr60Al15Ni25非晶合金的晶化动力学。X射线衍射(XRD)和能谱(EDS)分析结果表明:Zr60Al15Ni25非晶合金晶化过程中的初生相为复杂三元化合物Al2NiZr6和AlNi4Zr5。非晶合金的有效晶化激活能反映了晶化初生相与非晶相间的结构差异,二者结构差异越大,有效晶化激活能就越高,Zr60Al15Ni25非晶合金的有效晶化激活能高达345 kJ/mol;当合金高温熔体快冷过程中的初生相与非晶合金的晶化初生相一致时,晶化动力学参数能够实际反映合金的玻璃形成能力,相反则不能。     

Resonant and non-resonant microwave absorption in the magnetoelectric YCrO3 through ferro-paraelectric transition

An electron paramagnetic resonance (EPR) study in the polycrystalline magnetoelectric YCrO₃ is carried out at X-band (8.8-9.8 GHz) in the 300-510 K temperature range. For all the temperatures, the EPR spectra show a single broad line attributable to Cr³⁺ (S = 3/2) ions. The onset of the ferro-paraelectric transition has been determined from the temperature dependence of three main parameters deduced from the EPR spectra: the peak-to-peak linewidth (ΔH_pp), the integrated intensity (I_EPR) and the g-factor; these parameters indicate a behavior in agreement with a diffuse phase transition. Low-field microwave absorption (LFMA) is used to give a further knowledge on this material; where this technique also gives evidence of the ferro-paraelectric transition.     

The influence of size effect of conductivity on the microwave absorption properties of thin Al films

采用中频磁控溅射法制备不同厚度的Al膜。利用直线型四探针法测量不同厚度Al膜的电导率,研究薄膜直流电导率随厚度的变化关系（尺寸效应）;并利用网络矢量分析仪测量Al膜与FR4-epoxy环氧树脂玻璃板复合结构微波吸收率,研究电导率尺寸效应对Al膜微波吸收性能的影响。实验结果表明：薄膜厚度对金属Al膜的电导率产生主要影响;在Al膜和FR4-epoxy环氧树脂玻璃板复合结构中,Al膜电导率变化对复合结构的最大吸收峰值以及吸收峰值对应的Al膜厚度会产生显著影响。实验结果利用传输矩阵方法计算得到了验证。     

二氧化硅气凝胶及其复合材料吸声性能的研究进展

制备出良好的具有高孔隙率的吸声材料对于噪声的控制至关重要。二氧化硅气凝胶凭借其高孔隙率和高声阻抗近年来越来越受关注,将其与传统吸声材料相复合可显著结合两者的吸声优势,对于噪声的消除具有很重要的意义。介绍了吸声性能的概念、吸声结构、机理以及测量表征方法,深入探究了空气流阻、密度、厚度、孔隙率、孔径、杨氏模量以及颗粒大小对气凝胶吸声性能的影响规律,详细综述了二氧化硅气凝胶与有机物、有机物/无机矿物以及非织造布复合材料吸声性能的研究进展,最后展望了目前面临的挑战和未来的发展方向。     

烧结电除尘灰中钾盐的回收及其浸出动力学

为了研究烧结电除尘灰中回收钾盐的强化浸出措施,使用ICP-AES、SEM-EDS和XRD分析技术对除尘灰的表面和内部形态,特别是钾盐的赋存形式进行分析。结果表明,该电除尘灰的主要成分是铁氧化合物,在其表面裸露吸附着一定含量的KCl晶体。水浸实验表明,该粉尘中的KCl可以通过水浸出、蒸发结晶的方式回收,其收率为18.56%。结晶产物的分析结果表明,KCl占61.21%,NaCl占13.40%,CaSO4占14.62%,K2SO4占10.86%。其水浸出动力学符合外扩散控制模型控制。强化浸出实验表明,提高浸出温度、加强搅拌、增加液固比等措施可以提高钾盐的浸出率和浸出速率。     

Transformation and leaching kinetics of silicon from low-grade nickel laterite ore by pre-roasting and alkaline leaching process

The mineralogical phase transformation of a low-grade nickel laterite ore during pre-roasting process and the extraction of silicon during alkaline leaching process were investigated. The results indicate that the reaction activity of nickel ores is effectively improved by pre-roasting at 650 °C for 2 h, because of the transformation of lizardite into magnesium olivine and protoenstatite. When finely ground ore samples (44–61 μm) pre-roasted firstly react with sodium hydroxide solution (60 g/L) with a solid/liquid ratio of 1:5 at 140 °C for 120 min, the extraction of silicon can reach 89.89%, and the other valuable elements of magnesium, iron and nickel are accumulated in the solid residues. The leaching kinetics of nickel laterite ore can be described successfully by the diffusion through the product layer control model. The activation energy is calculated to be 11.63 kJ/mol and the kinetics equation can be expressed as 1–3(1–x)^2/3+2(1–x)=13.53×10^?2exp[–11.63/(RT)]t.     

Magnetic properties and crystallization kinetics of Zn_(0.5) Ni_(0.5) Fe_2O_4

Precursor of nanocrystalline Zn0.5Ni0.5Fe2O4 was obtained by grinding mixture of ZnSO4·7H2O,NiSO4·6H2O,FeSO4·7H2O,and Na2CO3·10H2O under the condition of surfactant polyethylene glycol(PEG)-400 being present at room temperature,washing the mixture with water to remove soluble inorganic salts and drying it at 373 K.The spinel Zn0.5Ni0.5Fe2O4 was obtained via calcining precursor above 773 K.The precursor and its calcined products were characterized by differential scanning calorimetry(DSC) ,Fourier transform ...     

微波加热碳热还原铁酸锌的动力学及热力学

研究550-950°C下微波加热配碳还原焙烧分解铁酸锌生成ZnO和Fe3O4/FeO的工艺及机理。利用HSC热力学软件对铁酸锌分解的热力学温度进行计算,并利用碳气化控制、化学控制及扩散控制模型研究样品中铁酸锌分解的动力学行为。分析微波功率、反应温度、配碳比和时间对铁酸锌分解率的影响。结果表明：在微波加热温度750°C,C/ZnFe2O4质量比为1：3,粒径74~89μm,微波功率1.2 kW的条件下,被还原的铁酸锌样品经过浸出后,Zn的回收率可以高达97.93%。通过采用不同的动力学模型对分解动力学进行测试。结果表明：碳气化控制机制是良好的机制。碳气化反应的活化能为38.21 kJ/mol。     

球形钴颗粒的制备及吸波性能研究

以CoSO4?H2O为钴源,C4H4KNaO6?H2O为络合剂,N2H4?H2O为还原剂,NaOH为pH调节剂,CTAB为形貌控制剂,通过液相还原法成功制备出了具有特殊形貌的球形钴颗粒。采用扫描电子显微镜（SEM）,X-射线衍射仪（XRD）,振动样品磁强计（VSM）以及矢量网络分析仪对钴颗粒形貌、晶体结构、静磁性能以及微波频段内的电磁参数进行表征。研究表明钴颗粒的比饱和磁化强度为123emu/g, 矫顽力为176Oe。钴颗粒在9.8GHz、15GHz时出现明显介电损耗峰。钴颗粒复磁导率实部随着频率增加逐渐降低,显示了良好的频散特性,而虚部在微波频段内呈现宽化的共振峰,经分析为自然共振和交换共振共同作用所致。根据传输线原理计算反射损耗,发现当厚度为5.5mm时在12.4GHz处得到最大反射损耗-13.2dB,此时有效损耗频宽（≤-10dB）为1.6GHz,制备的钴颗粒具有良好的吸波特性。