CVD金刚石膜投资财务分析

文章从经济的角度,通过专业的财务分析,对CVD金刚石膜这一新型材料的投资价值进行研究。研究认为,CVD金刚石膜将成为金刚石材料未来发展的主流,其材料和制品具有广阔的市场前景。因此,投资CVD金刚石膜将获得丰厚的经济回报。     

热丝CVD法金刚石膜生长速度研究

本文使用热丝ＣＶＤ法着重研究了基底表面的处理、工作气压、碳化物的含量、基底温度、灯丝温度以及基底与灯丝间距离等对金刚石膜生长速度所产生的影响，并在以上研究的基础上采取措施，使热丝ＣＶＤ法生长金刚石膜的速度提高了４倍。     

不同晶粒尺寸对CVD金刚石膜机械性能的影响

采用热丝辅助化学气相沉积（CVD）工艺制备出纳米、微米及细晶粒金刚石膜材料。观察了这三种金刚石膜的表面形貌并对上述金刚石膜的物理机械性能包括抗弯强度和耐磨性进行了实验性研究。结果表明,细晶粒结构的金刚石膜具有最高的抗弯强度．纳米结构的金刚石膜耐磨性最好。综合两个技术指标认为：细晶粒金刚石膜是三种晶粒结构中最佳的刀具制造材料。     

热丝CVD法高速生长金刚石膜研究

使用热丝ＣＶＤ研究了碳源种类，氧气含量，灯丝温度，基底与灯丝间距离及异常辉光放电等对金刚石膜生长速度的影响，在此研究的基础上，优化工艺参数，使热丝ＣＶＤ法生长金刚石膜的速度提高到２０μｍ／ｈ。     

热丝CVD法制备大面积高质量自支撑金刚石厚膜

采用热丝CVD方法,在Ф110mm的钼基体上,以丙酮为碳源,在高纯氢的作用下,成功地合成了高质量自支撑金刚石厚膜.X射线、SEM和拉曼光谱分析表明,所合成金刚石厚膜质量均匀,晶体单一、完好、纯度高,生长速度快,已接近制备实用化的金刚石膜的要求.     

CVD金刚石切削工具

阐述金刚石切削工具在机加工中的重要作用和CVD金刚石的优异性能以及CVD金刚石切削工具的形式.对CVD金刚石薄膜切削工具和CVD金刚石厚膜切削工具的特点和应用范围进行了分析对比,并指出存在问题和发展前景.     

CVD金刚石膜激光打孔温度场有限元仿真

化学气相沉积金刚石膜是聚优异力学、电学、热学性能于一体的材料.金刚石激光打孔过程中存在特有的石墨化现象使得其温度场的分布有别于其他材料,因而,开展CVD金刚石膜激光打孔温度场研究对于理解热加工机理和进行参数优化具有重要的指导意义.本文首先建立了考虑金刚石石墨化过程的激光打孔热力学模型,根据有限元模型开展对CVD金刚石膜激光打孔有限元仿真研究,得到激光打孔温度场和金刚石石墨化的分布规律,并讨论激光能量、脉冲宽度、重复频率对单个脉冲去除量和石墨化程度的影响.仿真结果表明:单个脉冲平均去除量和石墨化程度均随着激光能量、脉冲宽度、重复频率的增加而增加,但激光能量的影响最为显著;当激光能量取0.5～1.6 J,脉冲宽度取300～800 ns,重复频率取30～60 Hz时既可以得到很高的加工效率同时又可以获得热影响区域较小的加工效果.     

论CVD金刚石合成技术及其发展趋势

阐述HPHT金刚石发展的局限性与CVD金刚石的进展历程。论述以CVD技术合成金刚石的方法及其发展趋势,包括提高CVD速度和改进CVD金刚石性质。     

CVD金刚石薄膜技术发展现状及展望(上)

简要描述了CVD金刚石薄膜技术的发展历程.介绍了纳米特别是超纳米金刚石膜、CVD金刚石大单晶的技术特点及其应用.超纳米金刚石膜在MEMS(微机电系统)、电化学和生物医学上的应用和CVD金刚石大单晶是当前的研究热点.简言之,金刚石的发展向着更大或者更小的方向深入进行,即“非大即小”.     

CVD金刚石薄膜技术发展现状及展望(下)

简要描述了CVD金刚石薄膜技术的发展历程。介绍了纳米特别是超纳米金刚石膜、CVD金刚石大单晶的技术特点及其应用。超纳米金刚石膜在MEMS(微机电系统)、电化学和生物医学上的应用和CVD金刚石大单晶是当前的研究热点。简言之,金刚石的发展向着更大或者更小的方向深入进行,即"非大即小"。     

CVD金刚石膜超精密度刀具技术研究

文章对CVD金刚石的物理特性进行了描述,研究了CVD金刚石膜制作超精密刀具的工艺技术方法,设计了生产工艺流程,对生产的CVD金刚石膜直刃和圆弧超精密刀具的精度及加工件的精度进行了测试,表明CVD金刚石膜是一种非常优异的超精密刀具的制作材料,应用前景非常广阔.     

Hall effect of photocurrent in CVD diamond film

Transient Hall voltage of photocurrent excited by the modulated light with photon energies near bandgap is observed in undoped and B-doped CVD diamond films. It is seen that photo-carriers created in the films by the band-to-band excitation higher than 5.5 eV are almost holes and the contribution of electrons is about 7% in the undoped film and 0% in the B-doped film. Photo-carriers excited by the light with photon energies 4.7 to 5.5 eV, in which the step-like absorption band is observed, are holes, which agrees with the result of the temperature dependence of the photocurrent excited by the light with the photon energies.     

Secondary electron amplification using single-crystal CVD diamond film

The current amplification characteristics of an unbiased 8.3-μm-thick single-crystal CVD diamond film are examined using secondary-electron-emission measurements. In particular, the intensity and energy distribution of transmitted and reflected secondary electrons are measured and used to examine the transport and emission properties that govern the current amplification process. Overall, the measurements confirm the excellent transport and emission properties of single-crystal CVD diamond, as compared to polycrystalline CVD diamond films studied previously. Specifically, the transmitted and reflected energy distributions measured from the single-crystal diamond are nearly identical, with a sharp, narrow (FWHM = 0.35 eV) emission peak dominating the spectra. However, the transmitted distributions are more fully thermalized as a result of the longer transport distances. In fact, transmitted electrons are detected even after traveling more than 8 μm through the film, which demonstrates the potential for excellent transport efficiency. Maximum transmission gains of 3–4 are obtained, which is encouraging under such field-free conditions. However, the results of the study indicate that the transmission process is being limited by diffusive transport in the unbiased diamond film.     

Morphology dependence of cathodoluminescence spectra of CVD diamond film

Translucent polycrystalline diamond film made by a DC plasma CVD method was investigated with cathodoluminescence spectroscopy and topography. Shift and/or splitting were found in peaks of several luminescence bands, 575, 532, 480, 460, 389, 270 (5RL) and 235 nm (FE), suggesting considerable magnitude of residual stress is present in the film. The behavior of the splitting was different for the different peak, indicating that the symmetries of the associated defects are different. The film after heat treatment at 6 GPa and 1800 °C was found to exhibit new luminescence bands approximately 300 and 500 nm. Splitting of the 575 nm peak was recognized to decrease with the heat treatment, suggesting that the residual stress was reduced.     

TEM interfacial characterization of CVD diamond film grown on Al inter-layered steel substrate

Al interlayer is precoated on pure iron or steel substrates for diamond film deposition. Microstructures and compositions around the interfacial region of diamond film/Al interlayer/substrates have been comprehensively analyzed by transmission electron microscopy (TEM). Using only a simple Al thin layer is not sufficient, as the integrity of the Al interlayer is easily destroyed during scratching pretreatment. Consequently, the continuity of diamond film is damaged and local carburization corrosion occurs on the substrate. The carburization products primarily consist of voluminous graphite and a large number of fine particles of iron carbide are dispersed at the interfacial region, inducing deteriorated interfacial adhesion. To solve it, an interdiffusion pretreatment of Al interlayer under annealing vacuum is required. The results show that a Fe–Al alloy facilitated the formation of a protective Al oxide layer and improved the diamond film deposition. However, the surface aluminizing process needs to be further optimized, as indicated by a comparison with the diamond deposition directly on Fe–Cr–Al bulk alloy substrate.     

Local field electron emission from grain boundaries of CVD diamond film

In this article, we have investigated local field electron emission from grain boundaries of diamond films with (100) preferential orientation by double-probe scanning electron microscopy (SEM). Compared with the field emission from the plane area of diamond film, local field emission from grain boundary area is greatly enhanced at the same applied field, and further increased with the increasing of grain boundary number density. This result provides a direct evidence that grain boundary plays an important role in field emission from diamond film because a great deal of sp² graphitic carbon phases exists in grain boundary areas as electron transport channels for the surface field emission process.