共查询到18条相似文献,搜索用时 15 毫秒
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Thin diamond films grown by chemical vapor deposition (CVD) process on Si substrates under similar deposition conditions in the microwave-excited (MW) and direct current (DC) plasma discharges were taken for comparative examination. Raman spectra, photoluminescence (PL) spectroscopy, and color cathodoluminescence scanning electron microscopy (CCL-SEM) have been used for characterization of the structure and composition features of poly-crystalline diamond films. No essential difference in Raman spectra for the CVD diamond films was detected. A significant difference was revealed in the PL spectra and in CCL-SEM images. 相似文献
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利用金属有机化学气相沉积(MOCVD)技术在蓝宝石衬底上生长一层高质量的ZnO薄膜。为了考察沉积温度对样品的非线性特性的影响,在200~500 ℃生长了一系列ZnO薄膜。用X射线衍射谱(XRD)及扫描电镜(SEM)对样品结构进行了评价。以Nd:YAG激光器输出的1.06 μm的激光为基频光,对ZnO薄膜样品的二阶及三阶非线性光学特性进行了实验研究。实验发现,对于250 ℃沉积温度的样品有较强的非线性效应,实验测得的二阶非线性极化张量 χ (2)ZZZ=9.2 pm/V, 三阶有效非线性系数χ(3)=5.28×10-20 m2/V2。 相似文献
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The tribology behaviors of diamond and silicon dioxide (SiO2) nanoparticles were examined via molecular dynamics simulations; four cases were simulated. At low velocity and low load, the nanoparticles separated the two blocks from each other and acted as ball-bearings. The plastic deformation, temperature distribution, and friction force were all improved due to the action of the nanoparticles. However, the crushing of the SiO2 nanoparticles was accompanied by deformation-induced loss of the rolling effect, when the load was increased. Without nanoparticles, a transfer layer formed at high velocity and low load. The two nanoparticles provided support for a certain duration. However, at high velocity and high load, the support effect of these nanoparticles was lost in a short sliding time. 相似文献
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Carbon nitride thin films may become good competitors for diamond-like carbon, due to their high hardness, high wear resistance, and low friction coefficient. At present, there are only a few studies of the effect of CN
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coating hardness and internal stress on its tribological properties, such as coating life and frictional behaviour. This work deals with tribological and mechanical properties of a carbon nitride coating prepared by ion-beam-assisted deposition (IBAD). Friction coefficients in the range of 0.10–0.12 were observed for the best CN
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coatings sliding against silicon nitride under ambient conditions. A nonlinear correlation between coating life and its internal stress and hardness was found. 相似文献
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After finishing the precision conditioning of mono-layer nickel electroplated coarse-grained diamond wheels with 151 μm (D151), 91 μm (D91) and 46 μm (D46) grain size, resp., profile and surface grinding experiments were carried out on a five-axis ultra-precision grinding machine with BK7, SF6 optical glasses and Zerodur glass ceramic. A piezoelectric dynamometer was used to measure the grinding forces, while an atomic force microscopy (AFM), white-light interferometer (WLI)) and scanning electron microscope (SEM) were used to characterize the ground surface quality in terms of micro-topography and subsurface damage. Moreover, the wear mechanics of the coarse-grained diamond wheels were analyzed and the grinding ratio was determined as well, in aiming to evaluate the grinding performance with the conditioned coarse-grained diamond wheels. Finally, the grinding results were compared with that of the fine-grained diamond wheels with regard to the ground specimen surface quality, process forces and wheel wear as a function of stock removal. The experimental results show that the precision conditioned coarse-grained diamond wheels can be applied in ductile mode grinding of optical glasses with high material removal rates, low wheel wear rates and no dressing requirement yielding excellent surface finishes with surface roughness in the nanometer range and subsurface damage in the micrometer range, demonstrating the feasibility and applicability of the newly developed diamond grinding technique for optical glasses. 相似文献
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Organosilane monolayers are novel ultrathin films used to control the physicochemical properties, such as friction and wear, of solid surfaces. In this study, the authors prepared alkylsilane and fluoroalkylsilane monolayers with a series of chain lengths by a chemical vapor adsorption method. The monolayers tribological properties were investigated by lateral force microscope (LFM) and friction tester. LFM nanoscale measurements of tribological properties showed that alkylsilane monolayer gave lower lateral force than the Si substrate surface. The lateral force decreased as the length of the alkyl chain increased. On the macroscale, friction test revealed that the organosilane monolayers gave lower dynamic friction coefficients than the Si substrate surface in air at room temperature. The longer the alkyl chain, the greater the wear resistance of the organosilane monolayers. Friction experiments using tetradecane as a lubricant showed better tribological properties than were obtained in air. Furthermore, microscopically line-patterned two-component organosilane monolayers were prepared and their macroscopic friction behavior was investigated. Even though the height difference between the two-components was less than 1 nm, friction force anisotropy between the parallel and perpendicular directions against the line pattern was observed. 相似文献
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HALINA GARBACZ MAGORZATA LEWANDOWSKA WACAW PACHLA† & KRZYSZTOF J. KURZYDOWSKI 《Journal of microscopy》2006,223(3):272-274
The aim of the present study was to examine the potential of hydrostatic extrusion for the fabrication of high‐strength materials for medical applications. The materials examined were 316LVM steel and technically pure titanium. The microstructures and mechanical properties of the materials before and after hydrostatic extrusion were analysed. It was found that the hydrostatic extrusion process resulted in a substantial refinement of the material microstructures. The refinement of the microstructure was accompanied by an improvement of the mechanical properties, such as the microhardness and yield stress. 相似文献
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《Measurement》2016
In this research work, an effort has been made to study the influence of fused deposition modelling (FDM) and chemical vapor smoothing (CVS) process parameters on the selected linear and radial dimension as well as on repeatability of acrylonitrile butadiene styrene (ABS) replicas as a case study. The study highlights that orientation of parts on FDM build platform, part density (part interior style) and interaction between these two parameters significantly affect the accuracy of selected dimensions. Shrinkage has been observed in the selected radial dimension of the prototypes, but there is a positive deviation in the linear dimension from the desired value. The CVS process reduces both the dimensions slightly due to reflow of the material. Optimum parameter settings that were different for both linear and radial dimensions have been investigated using Taguchi’s L18 orthogonal array. The IT grades of ABS replicas prepared by this combined process were found to be consistent with the permissible range of tolerance grades as per ISO standard UNI EN 20286-I (1995) and DIN 16901 for plastic materials. Finally, optimum level of process parameters that simultaneously minimizes the deviation in both the dimensions have been found out using response optimization module of Minitab 17 software and the results obtained have been verified by performing the confirmation experiments. 相似文献
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《Tribology - Materials, Surfaces & Interfaces》2013,7(3):117-125
Ternary single and gradient layer (Cr, Ni) N thin films were deposited on the mild steel substrate by unbalanced magnetron sputtering technique in order to evaluate mechanical properties for machine tools and automotive applications. Microstructure, chemical composition, surface morphology and phase analysis were carried out using field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy and X-ray diffraction, respectively. Both single and gradient layer of (Cr, Ni) N coatings show a significant increment in mechanical properties such as hardness, adhesion strength and surface roughness along with the reduction of friction coefficient. Mechanical tests revealed that the hardness of the gradient layer increased up to 3.1 times due to the formation of Cr2N and Ni phase whereas single layer showed the least friction. Single layer CrNiN layer exhibited 27.2% less surface roughness (Ra) in comparison with gradient layer. High values of surface roughness, hardness, thickness and friction could be correlated with high film-to-substrate adhesion (Lc2) for the gradient layer. 相似文献
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《Measurement》2014
The effects of pH on the structural, morphological and optical properties of TiO2 nanorods were investigated. Nanorods were fabricated on p-type (1 1 1)-oriented silicon substrates and all substrates were seeded with a TiO2 seed layer synthesized with a radio-frequency reactive magnetron sputtering system (the TiO2 seed layer was also examined in this research). Chemical bath deposition (CBD) was performed to grow rutile TiO2 nanorods on Si substrate at various pH values (0.5, 0.7 and 0.9). Raman spectroscopy, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analyses showed the tetragonal rutile structure of the synthesized TiO2 nanorods. Optical properties were examined photoluminescence spectroscopy, which indicated a high-intensity UV peak centered at around 390 nm for all samples compared with visible defect peaks. Experimental results showed that the TiO2 nanorods grown at pH 0.7 exhibited the optimal structural properties. Moreover, the CBD method enabled the formation of photosensitive and high-quality rutile TiO2 nanorods with few defects for future optoelectronic nanodevice applications. 相似文献
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Structural, mechanical and tribological investigations of sputter deposited CrN-WS2 nanocomposite solid lubricant coatings 总被引:1,自引:0,他引:1
B. DeepthiHarish C. Barshilia K.S. RajamManohar S. Konchady Devdas M. PaiJagannathan Sankar 《Tribology International》2011,44(12):1844-1851
Nanocomposite coatings of CrN-WS2 were prepared at different Cr contents (approximately 8-39 at%) using an unbalanced magnetron sputtering system. Structural changes in CrN-WS2 coatings with variation in Cr content were studied using X-ray diffraction. CrN-WS2 coatings displayed a dense, compact microstructure with reduced columnar growth in the field emission scanning electron microscopy data. Nanoindentation and nanoscratch data showed that CrN-WS2 coatings exhibited improved mechanical and adhesive properties, respectively. Micro-tribometer tests at a load of 2 N indicated that CrN-WS2 coatings prepared at 31 at% Cr exhibited a stable friction coefficient of 0.20-0.24 even after 8 h. 相似文献
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The role of substrates on the structural,optical, and morphological properties of zno nanotubes prepared by spray pyrolysis 下载免费PDF全文
ZnO films were deposited onto glass, ITO coated glass, and sapphire substrate by spray pyrolysis, and subsequently annealed at the same temperature of 400°C for 3 h. The role of substrate on the properties of ZnO films was investigated. The structural and optical properties of the films were investigated by X‐ray diffractometer (XRD) and photoluminescence (PL) spectrophotometer, respectively. The surface morphology of the nanostructured ZnO film was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Crystallographic properties revealed that the ZnO films deposited on sapphire and ITO substrates exhibit a strong c‐axis orientation of grains with hexagonal wurtzite structure. Extremely high UV emission intensity was determined in the film on ITO. The different luminescence behaviors was discussed, which would be caused by least value of strain in the film. Films grown on different substrates revealed differences in the morphology. ZnO films on ITO and sapphire substrates revealed better morphology than that of the film on glass. AFM images of the films prepared on ITO show uniform distribution of grains with large surface roughness, suitable for application in dye sensitized solar cells. Microsc. Res. Tech. 77:211–215, 2014. © 2013 Wiley Periodicals, Inc. 相似文献
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采用ICP-AES法对2E12铝合金中钛、铜、镁、锰、锌、铬、硅和铁的测定进行了研究,着重进行了基体元素及待测元素在测定浓度范围内的线性相关性试验,进行了酸度试验,测定了2E12铝合金中8种元素的含量,得到了较好的精密度和准确度.方法简便,可靠,获得了满意的分析结果. 相似文献
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Fatih Bulut Özgür Ozturk Selim Acar Gürcan Yildirim 《Microscopy research and technique》2022,85(4):1502-1517
In the present study, the one-dimensional ZnO nanorod structures are produced within the different nickel and aluminum molecular weight ratios of 0–7% using the hydrothermal method. It is found that the aluminum (Al) and nickel (Ni) impurities with different ionic radius, chemical valence, and electron configurations of outer shell cause to vary the fundamental characteristic features including the crystallinity quality, crystallite size, surface morphology, nanorod diameter, optical absorbance, energy band gap, resistance, gas response, and gas sensing properties. The structural analyses performed by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicate that the samples are found to crystallize in the hexagonal wurtzite structure. The presence of optimum nickel and aluminum in the crystal system improves considerably the crystallinity quality and surface morphology. Additionally, the combination of electron dispersive X-ray (EDX) and XRD results declare that the Ni and Al impurities incorporate successfully into the ZnO crystal structure. Moreover, the diameters of nanorod structures in 1D orientation are determined to be 80 nm or below. The hexagonal wurtzite-type ZnO nanorod structure prepared by 5% Ni has more space between the nanorods and thus presents higher response to the CO2 detection. Further, the optical absorbance spectra display that the band gap value is observed to decrease regularly with the increment in the doping level as a result of band shrinkage effect depending on the enhancement of mobile hole carrier concentrations in the crystal structure. In other words, the doping mechanism leads to vary the homogeneities in the interfacial charges, nanorod diameters, ZnO oxide layer composition and thickness. The last test conducted in this study is responsible for the determination of CO2 gas sensing levels. The obtained gas sensing results are further compared with each other and literature findings. It is observed that 5% Ni-doped sample provides more successful results than other samples in the sensing CO2 gas at the different concentrations. All in all, the paper establishing a strong methodology between doping mechanism and change in the fundamental characteristic features of hexagonal wurtzite-type ZnO with the aid of advanced microscopy techniques will become pioneering research to answer key questions in materials sciences and electronic research. 相似文献