液相沉积类金刚石膜的结构与性能研究

探讨了液相沉积法制备类金刚石的新工艺,并采用XPS,Raman光谱和SEM等对所得膜的结构进行表征,证实所得的是类金刚石膜。液相沉积得到的类金刚石膜与钛合金基材之间具有较强的结合强度,并具有较低的摩擦系数和一定的耐磨损能力。     

类金刚石膜的结构与性能研究

用激光Ｒａｍａｎ谱和ＸＲＤ谱对用直流－射频等离子体化学气相沉积法制备的类金刚石膜的结构进行了分析，并研究了工艺参数对膜的沉积速率，内应力和直流电阻率的影响，结果表明，类金刚石膜是由ｓｐ＾２和ｓｐ＾３键组成的非晶态碳膜，当负偏压高于３００Ｖ时，膜中ｓｐ＾３／ｓｐ＾２键的比值随负偏压的升高而降低，类金刚膜的沉积速率与负偏压Ｖｂ的成正比，膜内存在１～４．７ＧＰａ的压应力，随负偏压的升高而降低，膜的电阻率     

金刚石膜电极电化学处理污染物的研究

采用人工合成的金刚石膜电极进行电化学氧化降解处理污染物的探索工作。已成为环境电化学领域中最为关注的国际性研究热点之一。从电催化氧化降解技术处理污染物的研究现状及其存在的问题出发．分析了适用于污染物降解处理的高效电极材料应具有的表面特性及其电化学性质。在综述了金刚石膜电化学研究以及应用于污染物处理的工作基础上,结合近期相关的研究结果,论述了金刚石膜电极的电化学特性以及对污染物氧化降解的应用和降解机理。金刚石膜电极将是未来环保处理中非常适用、高效、稳定的电极材料。     

金刚石膜与冷阴极场发射显示器

金刚石膜的出现突破了传统人造金刚石尺寸的限制,使得金刚石的电学、热学、光学和电子学等方面的优异性能得到了利用,极有可能为超硬材料行业开拓新的更大的市场.金刚石膜或类金刚石膜用来作为场发射的阴极,是其极具前景的应用之一.文章叙述了冷阴极场发射的概念、金刚石膜的性能和用作冷阴极场发射显示器的相关研究,介绍了国内外相关研究的成果和发展前景,供同行参考.     

荷能粒子在类金刚石膜形成中的应用

类金刚石膜由于其优异性能和广泛应用已引起越来越多的研究兴趣。尽管各种化学和等离子体辅助ＣＶＤ和ＰＶＤ技术已用来沉积类金刚石膜（ＤＬＣ膜）,但其形成机理仍不清楚。本文通过分析荷能离子的作用,应用热峰效应和离子刻蚀效应来解释ＤＬＣ膜的形成。     

光学玻璃上HFCVD法沉积金刚石膜的实验研究

采用热丝化学气相沉积(HFCVD)技术在石英玻璃上成功制备出高质量金刚石膜.采用表面三维轮廓仪和傅立叶红外光谱仪测试了不同工艺条件下金刚石薄膜的表面粗糙度和红外透射率,并分析了测试结果.结果表明所制备的金刚石膜表面平整,红外透射性能良好.     

日本汽车推出无氢类金刚石碳膜涂料

日本汽车公司（Nissan）的无氢类金刚石碳膜涂料（DLC）最近获得了由日本贸易经济产业部（METI）颁发的第二届Monozukuri Nippon涂料类产品和科技发展大奖。     

类金刚石膜的性能、制备及其应用

类金刚石膜是无定形碳中含sp3键的亚稳态结构.由于它的组成、光学透过率、硬度、折射率和在化学腐蚀剂中的惰性以及抗摩擦性能十分相似于金刚石,其应用领域不断被拓宽,因此对类金刚石的研究也日益成为热点.本文介绍了类金刚石的性能、制备类金刚石膜的物理气相沉积和化学气相沉积方法,概括了类金刚石膜在机械、电磁学、光学、医学以及其它领域的应用,最后指出了类金刚石膜的研究现状及其发展趋势.     

PECVD类金刚石涂层的结构及其摩擦腐蚀行为

采用等离子体增强化学气相沉积技术(PECVD)在316L不锈钢上制备类金刚石(DLC)涂层,系统地研究了所制备类金刚石涂层的表面形貌与结构、不同载荷下的摩擦磨损行为以及NaCl溶液(3.5 wt%)中不同腐蚀时间下的腐蚀行为。研究结果表明：制备的DLC涂层是由sp³键和sp²键杂化形成的非晶碳结构,其中sp²-C含量大于sp³-C,具有典型的类金刚石碳特征;DLC涂层结构致密,表面平滑,粗糙度仅为Ra=12.1 nm,能够与316L不锈钢基体结合紧密;DLC涂层的接触角为59.44°,说明涂层表现出一定的润湿性;摩擦磨损测试结果表明DLC涂层具有良好的润滑效果,摩擦系数能低至0.07～0.16,磨损率低至(3.85～6.71)×10^-7 mm³/(N·m);电化学测试得到DLC涂层自腐蚀电流密度为6.72×10^-6 A·cm^-2,阻抗模值高达7.05×10⁴Ω·cm^-2...     

Effect of microwave power on diamond-like carbon films deposited using electron cyclotron resonance chemical vapor deposition

Diamond-like carbon (DLC) films have been deposited using electron cyclotron resonance chemical vapor deposition (ECR-CVD) under various microwave power conditions. Langmuir probe measurement and optical emission spectroscopy (OES) were used to characterize the ECR plasma, while the films were characterized using Raman and infrared (IR) spectroscopies, hardness and optical gap measurements. It was found that the ion density and all signal peaks in the optical emission (OE) spectra increased monotonously following the increase in microwave power. Raman spectra and optical gap measurements indicate that the films become more graphitic with lower content of sp³-hybridized carbon atoms as the microwave power was increased. IR and hardness measurements indicate a reduction in hydrogen content and decrease in hardness for the film produced at relatively high microwave powers. A deposition mechanism is described which involved the ion bombardment of film surfaces and hydrogen–surface interactions. The deposition rate of DLC film is correlated to the ion density and CH₃ density.     

Characterization of diamond-like carbon films before and after heavy energetic ion implantations

Hydrogenated diamond-like carbon films were implanted by 110 keV Fe⁺ at doses ranging from 1 × 10¹³ to 5 × 10¹⁶ ions cm⁻². The film resistivities and the infra-red transmittances of the specimens were determined as functions of the implanted doses. Raman spectra and the infra-red transmittances of the film layers were used to characterize the structural changes of the implanted films. It was found that, when the implantation dose was higher than about 5 × 10¹⁴ or 1 × 10¹⁵ ions cm⁻², the film resistivity and the total infra-red transmittance of the specimens decreased significantly. However, when the dose was smaller than this value, the resistivity decreased firstly and then increased with dose and the measured values were higher than those of corresponding as-grown ones. The infra-red transmittance of the specimens was also improved to some extent under the lower dose range. By using structural characterization results, especially the infra-red transmittances of the film layers, we conclude that the electrical and optical property changes at doses higher than about 5 × 10¹⁴ or 1 × 10¹⁵ ions cm⁻² were due to the following changes, i.e., the decrease in the population of both sp² C-H and sp³ C-H bonds (compared with that of sp³ C-H bonds, the decrease in speed of sp² C-H bonds is smaller), the decrease of bond-angle disorder and the increased population of sp² C-C bonds. However, at doses between 1 × 10¹⁴ and 5 × 10¹⁴ or 1 × 10¹⁵ ions cm⁻², the implantation induced increase of C-H bonds was responsible for the observed property changes. Compared with the previous reports, the novelty of the present work is: the IR transmittance curves of the single film layers give us direct evidence for the changes of different C-H bonds with increasing ion dose and thus proved the transformation mechanism proposed previously.     

Structure and mechanical properties of W incorporated diamond-like carbon films prepared by a hybrid ion beam deposition technique

W incorporated diamond-like carbon films were prepared on silicon(1 0 0) wafers using a hybrid deposition system composed of an end-Hall-type hydrocarbon ion gun and a tungsten DC magnetron sputter source. The W concentration in the films was controlled by changing the fraction of Ar in the Ar and C₆H₆ reaction gas. The chemical composition, atomic bond structure, and mechanical properties were investigated for W concentrations ranging from 0 to 8.6 at.%. When the W concentration was <2.8 at.%, the W atoms were dissolved in the amorphous carbon matrix without forming a WC_1−x phase. Amorphous and crystalline WC_1−x nano-particles appeared when the W concentration was >2.8 and >3.6 at.%, respectively. It was found that the hardness and elastic modulus were not sensitive to the W concentration in this concentration range. On the other hand, the residual compressive stress was strongly dependent on the chemical state of the incorporated W atoms. The change in mechanical properties is discussed in terms of the microstructural changes induced by W incorporation.     

Iodine doping of amorphous diamond-like carbon films

Amorphous diamond-like carbon (a:DLC) films have been doped by incorporation of iodine during the films deposition. XPS and AES analysis shows the existence of iodine atoms with constant concentration of 0.9% along the iodine doped DLC film (a:I-DLC). The optical and electronic properties of the doped films were studied. Optical measurements in the visible light show that iodine affects the interband absorption of the a:DLC films. Iodine causes decreasing of the optical energy gap, from 1.07 to 0.78 eV and affects the density of states at the conducting band. Like the optical measurements, electrical measurements show that iodine also decreases the activation energy of the films from 0.34 to 0.22 eV. This shows that although both gaps decrease, the optical energy gap remains different from that of electrical gap, also after doping.     

Effect of N doping on properties of diamond-like carbon thin films produced by RF capacitively coupled chemical vapor deposition from different precursors

In this paper, we report results concerning properties of diamond-like carbon (DLC) thin films obtained in different experimental conditions: various RF power values and different precursors (methane, acetone and toluene or in combination with nitrogen). The deposition rate of DLC thin films obtained from precursors with low ionizing energy and high number of carbon atoms in molecule as acetone and toluene was higher (142 nm/min for acetone and 607 nm/min for toluene as compared with 79 nm/min for methane at 400 W input power). The highest value of hardness was obtained from methane (18 GPa). In the case of acetone and toluene precursors, the hardness increased with input power to the highest values of 16.8 and 14.8 GPa. By utilizing nitrogen as doping element, the resistivity of DLC thin films obtained from methane and acetone decreased from values higher than 10⁷ Ω cm to lower values of 12.5×10³ Ω cm for 3.79% nitrogen atomic concentration in the case of films obtained from methane and 40×10³ Ω cm for 4.26% nitrogen atomic concentration in the case of films obtained from acetone.     

Electrodeposition mechanism of hydrogen-free diamond-like carbon films from organic electrolytes

A brief introduction on the development of electrodeposition of diamond-like carbon (DLC) films was given, and our experiments were done, emphasizing on how to deposit hydrogen-free DLC films. Methanol, acetonitrile and N,N-dimethyl formamide (DMF) were chosen as electrolytes, while Si and conductive glass were used as substrates. The sample deposited on Si through methanol was the only one in this comparative research that produced hydrogen-free DLC film as it was indicated by the FTIR spectroscopy. Two explanations, based on reaction mechanism, were proposed to explain this fact. It was believed that the reaction rate and the effect of hydroxyl groups in the molecules of the electrolytes played important roles in the deposition of hydrogen-free DLC films.     

Characteristics of carbon films prepared by plasma-based ion implantation

A series of carbon films have been prepared by plasma-based ion implantation (PBII) with C on pure Al and Si. Emphasis has been placed on the effect of implanting voltage on the characteristics of these films. The structures of the films were analyzed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The morphologies were observed by atomic force microscope (AFM). Surface hardness and electrical resistivity were also measured. The results indicate that the characteristics of these films are strongly dependent on the implanting voltage. An implanting voltage threshold value ranging from 3 to 5 kV starts to form a C-substrate transition layer owing to C⁺ ions implanted into the substrate. The transition layer exhibits a gradual change in composition and structure and effectively connects the carbon film and the substrate. Also, an implanting voltage threshold value ranging from 5 to 10 kV starts to form diamond-like carbon (DLC) films. An increasing voltage causes the resultant DLC films to be smoother and more compact. Moreover, Raman spectrum, chemical state of C1s, surface hardness and electrical resistivity all prove an optimum voltage of approximately 30 kV corresponding to the lowest ratio of sp²/sp³.     

In situ measurement of stresses in diamond-like carbon films

In situ determination of stresses in thin films can be used as an important tool to assist process development as well as to understand the thermodynamics of film formation. A simple technique for the measurement of stresses in growing films is described here. The technique consists of measuring the displacement of a laser beam reflected from the film surface. Displacement is induced by changes in the radius of the curvature of the substrate resulting from stresses in the film. The detector sensitivity at the used wavelength (635 nm) is approximately 12 mV μm⁻¹, for which our experimental set-up is equivalent to 4 mV μrad⁻¹. The actual data collected consist of the reflected beam displacement vs. time, and provides at any instant the value of the average stress. By knowing the deposition rate, time is directly correlated with film thickness, and the local stress can be determined. Examples of measurement of stresses in tetragonally bonded amorphous carbon films prepared by filtered cathodic arc are presented, as well as how this technique can be used to design the deposition process to virtually eliminate intrinsic stresses.     

Local structure of composite Cr-containing diamond-like carbon thin films

Composite Cr-containing hydrogenated amorphous diamond-like carbon (Cr-DLC) films were synthesized by a hybrid PVD/CVD plasma-assisted deposition process. In a recent study, it was found that Cr-DLC films with <∼12 at.% Cr possess excellent tribological properties. However, the role of Cr in inducing these characteristics is not clear. In the present report, the local structure around the Cr atoms in the latter films was studied as a function of Cr content by X-ray absorption spectroscopy. The Cr K-edge X-ray absorption near edge structure spectra show that Cr in DLC has a chemical state similar to that of chromium carbide. Analysis of the extended X-ray absorption fine structure spectra shows that at low Cr content (<0.4 at.% Cr), Cr is dissolved in the amorphous DLC matrix forming an atomic-scale composite. Simulation studies suggest that in the latter films, Cr tends to be present as very small atomic clusters of 2-3 Cr atoms. At higher Cr contents (>1.5 at.%), Cr is present as nanoparticles (<10 nm) of a defected carbide structure forming a nanocomposite.