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1.
研制了一种新型铝电解金属陶瓷惰性阳极,阳极基体由Fe-Ni-CoAl2O3构成。在石墨坩埚中,960℃温度下,电解质中的氧化铝质量分数为60%,摩尔比为26;阳极电流密度为10 A/cm2,阳极尺寸大小为120 mm×80 mm×15 mm,石墨阴极尺寸大小为120 mm×40 mm×20 mm,通入的直流电为100~300 A,电解时间各为10 h;实验所得的电解铝产品纯度达到98%以上,杂质主要为Fe,Ni,Co;电解后的阳极外观尺寸无明显变化,阳极气体中氧气质量分数达到98%~99%。阳极的反电动势为245 V,比理论分解电压仅高出025 V证明该阳极为惰性阳极,在电解槽中进行的是Al2O3的分解反应。  相似文献   

2.
南京某厂从日本引进焊管机组,用带式法生产薄壁不锈钢管。其工艺流程如下: 钢带分剪→轧辊成型→钨极氩弧焊(TIG)焊成管坯→冷拔→矫直→成品。采用某厂一批0.3mm厚的1Cr18Ni9和0Cr19Ni9奥氏体不锈钢带试焊,发现有焊渣间隔分布于焊缝的内外壁上。间隔距离从5mm至100mm不等,大部分在20~30mm之间,见图1.焊渣多呈灰褐色,其形如纺锤状,尺寸(长×宽)约在(10~20)mm×(4~6)mm。  相似文献   

3.
以硫铁矿烧渣硫酸浸出液与氨水反应制备的Fe(OH)3胶体为前驱体,采用水热法合成不同形貌的氧化铁粒子。在中性介质中考察反应温度、物质的量比(n(Fe2+)/n(Fe3+))、水热体系总Fe浓度及晶种量对水热法氧化铁物相、形貌和粒径的影响。采用X线衍射仪、扫描电镜、透射电镜及选择区域电子衍射对水热产物物相和形貌进行研究。研究结果表明:反应温度为230℃,n(Fe2+)/n(Fe3+)为0.1以及水热体系总Fe浓度为1.25 mol/L和晶种量为2 g时,水热产物为片状α-Fe2O3粒子;控制上述其他条件不变,当温度在140~260℃时,随着温度的升高,水热法产物由α-FeOOH相向α-Fe2O3相转变,α-Fe2O3粒子形貌由球形向小圆饼状和片状依次转变;当n(Fe2+)/n(Fe3+)在0~0.12时,随着n(Fe2+)/n(Fe3+)的增加,水热产物由α-Fe2O3相向α-Fe2O3和Fe3O4相转变,α-Fe2O3粒子形貌由球形逐渐向片状转变,其粒径由小变大;当水热体系中总Fe浓度为0.625 mol/L和1.875 mol/L时,水热法氧化铁分别为不均一形貌和球形;当没有加入晶种及晶种量为6 g时,水热...  相似文献   

4.
掺钕钛酸铋纳米结构的水热合成研究   总被引:1,自引:0,他引:1  
以Bi(NO3)3·5H2O,Nd(NO2)3·6H2O和Ti(OC4H9)4为原料,NaOH为矿化剂,采用水热法合成铋层状钙钛矿掺钕钛酸铋(Bi3.15Nd0.85Ti3O12,BNdT)纳米结构.利用X射线衍射(XRD)、扫描电子显微镜(SEM)表征产物的晶相和形貌.研究反应温度、矿化剂浓度和反应时间对水热合成BNdT纳米结构的影响.结果表明,在适当的水热反应条件下能有效合成BNdT纳米结构,在反应温度为150℃、175℃、200℃和220℃时分别形成球状、球状与片状共存、棒状和片状产物.  相似文献   

5.
新型VCOCXO控温原理及实现方法研究   总被引:1,自引:0,他引:1  
提出了VCOCXO的一种新型控温方法 ,论述了其控温原理及实现 .从而研制成频率温度稳定度达到± 1× 10 -8( - 40~ 70℃ ) ,体积为 2 5mm× 2 5mm× 15mm的小型高稳恒温晶体振荡器  相似文献   

6.
唐宁莉 《广西科学》2004,11(3):233-235
根据pH值为5.0的HAc-NaAc溶液中,Cr6+催化H2O2氧化四氯四碘荧光索二钠的褪色反应,建立催化动力学光度法测定痕量Cr6+的新方法.新方法的检出限为1.05×10-9g/ml,测定线性范围为0~35μg/L Cr6+.新方法用于天然水中痕量Cr6+的测定,结果良好.  相似文献   

7.
描述了一种采用模拟温度补偿技术用于声表面波微波源 ,其工作频率为 2 .2 GHz,器件在工作温度为 - 35℃~ + 5 5℃范围内 ,频率变化从两百多 ppm改善到小于± 30 ppm之内 ,使器件在90℃的温度范围内频率随温度变化的性能改善约 10倍。其 g-振动灵敏度小于 10 - 1 0 /g。尺寸仅6 0 m m× 2 5 mm× 15 mm。  相似文献   

8.
描述了一种采用模拟温度补偿技术用于声表面波微波源 ,其工作频率为 2 .2 GHz,器件在工作温度为 - 35℃~ + 5 5℃范围内 ,频率变化从两百多 ppm改善到小于± 30 ppm之内 ,使器件在90℃的温度范围内频率随温度变化的性能改善约 10倍。其 g-振动灵敏度小于 10 - 1 0 /g。尺寸仅6 0 m m× 2 5 mm× 15 mm。  相似文献   

9.
以北方高寒地区玉米秸秆为研究对象,利用正交设计的试验方法,选取颗粒尺寸、堆积尺寸、堆积密度以及含水率为影响因素,在自制的阴燃试验台进行北方高寒地区玉米段状秸秆的阴燃特性的研究.研究表明:秸秆尺寸350 mm、堆积尺寸250 mm×350 mm×300 mm、堆积密度40 kg/m3、含水率20%时,炉腔内温度高、阴燃时间最长,最高平均温度为701.6℃,阴燃时间为145 min;阴燃时阴燃波自上而下,温度的变化自上向下逐渐升高,属于正向阴燃.  相似文献   

10.
A functionally graded material-based actively water-cooled tungsten-copper mockup with a dimension of 30 mm×30 mm×25 mm was designed and fabricated by infiltration-brazing method. The thicknesses of the pure W layer and W/Cu graded layer were 2 and 3 mm, respectively. High heat flux tests were performed on the mockup using an e-beam device. There is no damage occurring on the joint after heat loading at 5 MW/m2. The temperature on the pure W surface is less than 500℃ after irradiation for 100 s at 5 MW/m2, while the temperature on the brazing seam/copper surface is around 200℃.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

13.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

14.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

15.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

16.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

17.
For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the  相似文献   

18.
Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of  相似文献   

19.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

20.
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