首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
为分析多孔阳极氧化铝膜形态参数和氧化条件的关系,在恒流条件下对0.3 mol·L-1草酸电解中形成多孔膜的生长动力学进行了研究.采用扫描电子显微镜和氧化膜质量测定方法检验了电流密度、温度和氧化时间对氧化膜生长动力学和氧化膜形态的影响.通过电压-时间曲线研究了氧化膜的电化学特征,并采用一元线性回归模型预测了氧化膜的生长速率.实验结果表明氧化膜的生长速率随电流密度的升高而升高,随温度的升高而下降.氧化膜质量的增长速率也随着电流密度的升高而增大.  相似文献   

2.
以草酸溶液为电解质.采用两步电化学阳极氧化法制备了氧化铝有序多孔膜,研究了草酸浓度、阳极氧化电压以及草酸溶液温度对膨胀因子的影响。研究结果表明:铝的反应速率随电流密度的增大线性增加,电流效率为92%;随着工艺条件的改变,膨胀因子在1.270~1.425之间变化;在温度一定的情况下.膨胀因子与氧化电压呈线性关系,其倒数与电流密度的对数成正比;随着温度升高,电流密度增加.膨胀因子降低。  相似文献   

3.
本文采用电化学阳极氧化法制备多孔硅,考察不同氧化条件下多孔硅孔隙率及膜厚的变化情况,研究电化学阳极氧化工艺条件、高氯酸钠溶液浓度以及贮存方法等因素对多孔硅复合材料爆炸反应的影响。结果表明,多孔硅孔隙率随电流密度增大而增大,当电流达到50mA·cm~(-2)以上时略有降低,孔隙率随氧化时间增大而先增大后减小,且氧化时间为30min时最大,孔隙率随氢氟酸浓度增大反而减小;多孔硅膜厚随时间增大而增大。SEM分析表明,多孔硅表面产生裂缝,内部形成硅柱。在电流密度小、氧化时间短的条件下形成的多孔硅复合材料不易爆炸,当NaClO4甲醇溶液质量浓度大于0.098g·mL~(-1)时发生强烈爆炸,将多孔硅复合材料用乙醇浸泡是最为理想的贮存方法。  相似文献   

4.
采用电化学法及原电池法制备了多孔硅样品.通过在阳极氧化反应中HF溶液浓度、电流密度和反应时间的不同来控制多孔硅的孔隙率和膜厚.实验结果表明:不同电流密度下制备的多孔硅样品,孔隙度有相同的变化趋势,刚开始增加,然后减少;多孔硅的生长速度随电流密度的增加而升高.在多孔硅样品表面封装BST热释电敏感元件进行性能测试,结果表明...  相似文献   

5.
采用2次阳极氧化的方法制备了多孔阳极氧化铝膜.主要研究了阳极氧化电压、电解液种类、阳极氧化时间和阳极氧化温度对多孔阳极Al2O3膜生长的影响.并通过扫描电镜观察了其表面结构.讨论了多孔Al2O3膜生长的规律.  相似文献   

6.
针对磁化焙烧冷却过程开展了研究,考察了磁铁矿氧化反应分数和反应速率的变化规律,并采用模型匹配法进行了氧化动力学分析.结果表明:磁化焙烧冷却过程中,氧化温度对反应分数和反应速率均有着显著的影响;相同氧化时间下,反应分数和反应速率随氧化温度的升高而增加;不同氧化温度下,反应分数和反应速率随反应时间变化呈现出相同的变化规律;磁铁矿氧化过程动力学机理函数为n=4的Avrami-Erofee方程,氧化反应的表观活化能为135.2kJ·mol,指前因子为6.19×1010min-1.  相似文献   

7.
建立了考虑到热交换和质量交换情况下,电沉积过程中纳米粒子热力学函数满足的方程.探讨了电镀生长、动力学生长和扩散生长这3种生长机制情况下,粒子温度随粒子线度的变化规律.结果表明小岛生长开始时, 小岛温度随粒径增大而急剧升高;当小岛半径增大到开初的1.05倍时,温度缓慢降低;其中动力学生长降温最慢,而电镀生长降温最快.增大电流密度和电解液浓度不会改变小岛温度随粒径的变化情况,但会使温度有所升高.  相似文献   

8.
本研究采用电化学氧化法脱色染料亚甲基蓝溶液,研究了脱色反应速率常数,分析了脱色产物.实验结果表明,亚甲基蓝废水的脱色为拟一级反应动力学过程,在不同的温度288,298,308,318,328和338K,脱色反应速率常数为0.002 53,0.003 52,0.004 98,0.006 09,0.007 63和0.010 33s~(-1),脱色反应速率常数随温度升高而升高,升高反应温度有利于脱色反应的进行,反应活化能为21.61kJ/mol.HPLC-QTOF-MS检测脱色反应包括开环反应、氧化还原反应和聚合反应.电解时间效率曲线证明,电化学氧化脱色反应减少反应的电能消耗和处理时间.  相似文献   

9.
实验研究电解液温度、草酸浓度、草酸-硫酸混酸浓度、电流密度及膜层厚度等因素对阳极氧化铝膜的抗电强度的影响.结果表明,随生长条件不同,阳极氧化铝膜的抗电强度在50~120 V/μm范围内变化.其中,电解液温度对抗电强度影响大,降低电解液温度有利于抗电强度的提高;电流密度对抗电强度的影响存在最佳值特征,低于该值时,氧化终止电压低,随之膜层抗电强度低,高于该值时,氧化电压随电流密度非线性上升,热功耗过大导致实际氧化温度上升,抗电强度降低;草酸电解液制备膜层的抗电强度高,并随草酸浓度上升而提高,微量硫酸添加均会导致抗电强度的下降;抗电强度随膜层厚度增加呈现先上升后下降的特征.1  相似文献   

10.
主要介绍硼掺杂金刚石膜的生长.采用热灯丝CVD法在硅上制备金刚石薄膜,采用三氧化二硼制备硼掺杂金刚石膜.利用拉曼光谱分析硼掺杂金刚石膜的生长情况.结果表明:硼的掺杂质量分数随生长时间延长而增大;利用SEM观察硼掺杂金刚石膜的表面晶粒变小;利用银浆在掺杂金刚石膜表面制备电极,测试电流随温度升高而变大.  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.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
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   

14.
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   

15.
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   

16.
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   

17.
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   

18.
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   

19.
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   

20.
<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   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号