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1.
介绍了活性碳、碳黑与石墨在过剩压驱动下金刚石晶种的生长.对两种无定形碳以及石墨在触媒中的分散溶解输运与再结晶进行了观察,对活性碳、碳黑在金刚石晶种生长中的机理作了探索性的讨论.三种碳片上的晶种均有明显长大,无定形碳作晶种生长的碳源是可行的  相似文献   

2.
高温高压下无定形碳向金刚石结构转变的研究   总被引:1,自引:0,他引:1  
碳素材料是合成金刚石的原料。人们对熔媒参与下,石墨向金刚石转变研究得最多,并对这一转变过程提出了不同的解释。本文以无定形碳为碳源,来探讨其向金刚石的转变过程。通常使用石墨而不用无定形碳作碳源来合成金刚石,其原因在于无定形碳不具备直接转变成金刚石所必须的结构。实验表明:无定形碳向金刚石转变必须经过石墨化。无定形碳的石墨化过程是:构成三维排列的石墨晶体结构和石墨晶粒的长大。  相似文献   

3.
CVD金刚石膜{100}取向生长的原子尺度仿真   总被引:1,自引:0,他引:1  
运用动力学蒙特卡洛(KMC)方法从原子尺度对CVD金刚石膜{100}取向在3种不同化学反应模型下的生长进行了仿真.结果表明:(1)以CH3为主要生长组元的生长机制比较适合于{100}取向金刚石膜的生长;(2) 对金刚石{100}取向而言,含有双碳基团的模型沉积速度并不比含有单碳基团的模型沉积速度大;(3)在高的生长速率下仍有可能获得表面粗糙度较小的金刚石膜;(4)对Harris模型的仿真结果与其本人的预测结果一致,并与实验结果符合良好.  相似文献   

4.
火焰法沉积金刚石薄膜的组织结构   总被引:2,自引:0,他引:2  
用透射电镜(TEM)对大气中火焰法沉积(CFD)金刚石薄膜的组织结构进行了分析研究。结果表明,所沉积的金刚石晶体中(111)面上存在着大量层错及显微孪晶,在(111)面上晶粒边界处的位错密度较低,此外,在金刚石薄膜中还观察到存在于金刚石颗粒间的非金刚石型碳(C),即无定形碳及微晶石墨。  相似文献   

5.
利用水热金刚石压腔原位观测优势,结合显微镜高速录像技术,进行空气–H2O体系中气相溶解和出溶动力学实验研究.实验对金刚石压腔体系气泡生长、溶解过程进行原位实时记录,根据录像文件分解的照片来精确确定反应时间和温度,利用照片所记录的气泡半径随时间的变化来推算其体积生长参数和溶解程度.气–液相均一体系降温可促使气泡出溶,降温...  相似文献   

6.
利用直流热阴极辉光放电方法制备出了高品质金刚石厚膜,生长速率达到20μm/h,生长厚度达到3mm.为了解其工作特性、优化沉积工艺,本文研究了放电电压对金刚石沉积速率和品质的影响.通过对扫描电镜、拉曼谱和XRD图谱分析得出,随着放电电压的增加,沉积速率呈下降趋势,电压在850~950V范围金刚石中石墨和非晶碳明显减少,晶粒均匀,表面晶向以(110)为主,金刚石薄膜的质量显著提高.  相似文献   

7.
利用金刚石纳米粉引晶法和常规研磨方法分别在单晶硅衬底上制备金刚石薄膜,并采用扫描电镜、激光拉曼方法对所制备样品进行表征,通过SEM和拉曼谱分析,与研磨法生长金刚石薄膜相比,利用金刚石纳米粉引晶方法可以大大提高金刚石薄膜的成核速度,生长速率达到2μm/h以上。对相同碳源浓度下生长的金刚石薄膜样品的SEM和拉曼谱分析,采用引晶法生长的金刚石薄膜质量明显高于研磨法。  相似文献   

8.
在CVD法生长人造金刚石膜的过程中,活性物质是其生长的基础。通过本论文的实验证明,H.CH4是金刚石膜生长过程中的活性物质。本文并详细分析了H.CH4是如何在金刚石膜生长过程中产生金刚石的原子结构和键能,从而形成金刚石膜的。  相似文献   

9.
本文讨论了在真空状态下,碳离子淀积时产生金刚石成核的机理,作者认为高速运动碳离子打在非晶碳膜上产生了小范围的局部压力和热量.正是这个压强和高温使小范围内的非晶碳处于金刚石稳定的热力学状态.在此条件下小的金刚石核形成,同时经过迅速冷却保留下来.  相似文献   

10.
分析铁镍触媒合成金刚石内部的包裹体成分及形成原因. 结果表明: 金刚石晶体中的包裹体主要以FeNi合金和Fe3C形式存在; 随着生长速度加快, 金刚石内部包裹体的点状分布逐渐增多; 在不同温度下, 进入金刚石晶体内部包裹体的方式不同; 随着包裹体的增多, 合成的金刚石晶体硬度降低. 通过调整合成工艺, 合成了包裹体含量极少、 粒度约为0.6~0.7 mm的金刚石单晶.  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.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
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   

16.
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   

17.
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   

18.
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   

19.
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   

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   

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