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11.
Growth and Characteristics of Freestanding Hemispherical Diamond Films by Microwave Plasma Chemical Vapor Deposition 下载免费PDF全文
Freestanding hemispherical diamond films have been fabricated by microwave plasma chemical vapor deposition using graphite and molybdenum (Mo) as substrates. Characterized by Raman spectroscopy and scanning electron microscopy, the crystalline quality of the films deposited on Mo is higher than that on graphite, which is attributed to the difference in intrinsic properties of the two substrates. By decreasing the methane concentration, the diamond films grown on the Mo substrate vary from black to white, and the optical transparency is enhanced. After polishing the growth side, the diamond films show an infrared transmittance of 35-60% in the range 400-4000 cm^- 1. 相似文献
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利用微弧氧化(MAO)技术,在LYl2铝合金上沉积了显微硬度达42.14GPa的超硬陶瓷膜.采用x射线衍射仪和显微硬度计研究了阳极电流密度ja和阴极、阳极电流密度比jc/ja对MAO膜相构成和力学特性的影响.此外,利用扫描电子显微镜和恒电位仪分别对膜的微结构和抗点腐蚀特性进行了分析.结果表明,高ja制备的膜主要含α-Al2O3相,低ja制备的膜主要含γ-Al2O3相.显微硬度测试表明,这类膜有较高的硬度,但以ja=15A/dm2和jc/ja=0.7制备的陶瓷膜硬度最高.抗点腐蚀测试表明,jc/ja对陶瓷膜的微结构有很强的影响.
关键词:
微弧氧化
显微硬度
电流密度
抗点腐蚀 相似文献
13.
不同剂量的N离子被注入到化学气相沉积金刚石膜内,研究了表面结构及场发射特性的变化.Raman谱和x射线光电子能谱分析表明,N离子的注入破坏了金刚石膜表面原有的sp3结构,并在膜内形成大量的sp2 C—C 和sp2 C—N 键.样品的场发射测试显示N离子的注入显著提高了金刚石膜场发射特性,膜的场发射阈值电场从注入前的18 V/μm下降到注入后的4 V/μm.金刚石膜场发射特性的提高归因于N离子注入后膜内sp2 C键含量的增加和体内缺陷带的形成,这些变化能改变膜的表面功函数,提高Feimi能级,降低电子隧穿表面的能量势垒.
关键词:
场致电子发射
N离子注入
金刚石膜
热丝化学气相沉积 相似文献
14.
Instead of the conventional graphite, new additional reducing agents (diamond, silicon, metal elements, etc.) have been mixed with zinc oxide (ZnO) powder to fabricate ZnO micro/nanostructures by a thermal vapour transport method. Due to the strong reducibility for those additions, the corresponding heating temperature is decreased by 100 500℃ compared to the case of graphite, which subsequently decreases the corresponding growth temperature for the products. Being placed separately for the powder sources of ZnO and addition, a vapour-vapour reduction-oxidation reaction mechanism between the sources is proposed as an important channel to fabricate ZnO. Photoluminescence and magnetic examinations indicate that the ZnO products synthesized have strong ultraviolet (visible) emissions and are room-temperature ferromagnetic, meaning that the products are available for applications. 相似文献
15.
The specific features of electric current variation against time were studied by keeping the anode and cathode pulse voltage to be constant. The maximum thickness of the films fabricated by microarc oxidation was found to be closely related to the voltage. The surface morphology of the coatings can be divided into different stages according to the variation of electric current. A method for obtaining high micro hardness coating has been discussed. 相似文献
16.
Effect of CO2 Addition on Preparation of Diamond Films by Direct-Current Hot-Cathode Plasma Chemical Vapor Deposition Method 下载免费PDF全文
Diamond films are deposited on Mo substrates by dc hot-cathode plasma chemical vapor deposition method using a CH4-H2-CO2 gas mixture. Adjusting the flow of CO2, we study the relevant influence on surface morphology, grain orientation and crystalline quality of films with scanning electron microscopy, x-ray diffraction, Raman spectroscopy, respectively. The results show that grain orientation of the films has a transition with the increasing CO2 addition, from (100) orientation to (110) orientation and then (111) orientation. The crystalline quality is improved but the growth rate is decreased by raising the flow of CO2. The experimental results are also discussed briefly. 相似文献
17.
分析了影响金刚石膜热导率的主要因素,指出声子的散射是造成金刚石膜热导率降低的主要原因.采用光热偏转法实现了金刚石薄膜热导率的测试,测量误差小于5%,从减少杂质和晶界对导热声子的散射入手,研究了在不同的制备方法下碳源气体和金刚石膜内晶粒取向对其热导率的影响.结果表明在低碳源气体浓度下采用微波等离子体化学汽相沉积方法制备的具有较高程度(400)晶粒取向的金刚石薄膜具有高的热导率性质.优化的工艺条件制备出热导率为15.2W/(K·cm)左右的金刚石膜.
关键词: 相似文献
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Grainy titania coatings are prepared by microarc oxidation on pure titanium (TA2) substrates in a Na2SiO3NaF electrolytic solution. The coating thickness is measured by an optical microscope with a CCD camera. Scanning electron microscope (SEM) and x-ray diffraction (XRD) are employed to characterize the microstructure and phase composition of coatings. The results show that the coating thickness increases linearly as the treatment time increases. The coatings are mainly composed of anatase and rutile (TiO2). With the increase of treatment time, the predominant phase composition varies from anatase to rutile, which indicates that phase transformation of anatase into rutile occurs in the oxidizing process. Meanwhile, the size of grains existing on the coating surface increases and thus the surface becomes much coarser. 相似文献
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