纯钛TAl化学气相沉积表面改性层的耐磨性能研究

为提高TAl表面的耐磨性能，在TAl表面采用化学气相沉积(CVD)表面处理。用X射线衍射的方法测定了改性层的物相。使用显微硬度计测定了改性层和基体的硬度，在往复式滑动磨损试验机上进行磨损试验，通过扫描电子显被镜分析磨痕形貌。结果表明，TAl经过CVD处理，表面由α-Ti、Ti2N及TiN组成，显微硬度为989HV0．025。干摩擦条件下，经化学气相沉积处理的TAl材料的表面改性层的耐磨性得到了明显提高。     

纯钛TA1化学气相沉积表面改性层的耐磨性能研究

为提高TA1表面的耐磨性能,在TA1表面采用化学气相沉积(CVD)表面处理.用X射线衍射的方法测定了改性层的物相,使用显微硬度计测定了改性层和基体的硬度,在往复式滑动磨损试验机上进行磨损试验,通过扫描电子显微镜分析磨痕形貌.结果表明,TA1经过CVD处理,表面由α-Ti、Ti2N及TiN组成,显微硬度为989hV0.025.干摩擦条件下,经化学气相沉积处理的TA1材料的表面改性层的耐磨性得到了明显提高.     

镍改性层增强铜基底沉积金刚石膜的形核(英文)

在铜基底溅射约100nm厚的镍改性层,然后置入纳米金刚石悬浮液中超声震荡加载籽晶,随后在热丝化学气相沉积设备中制备出晶体颗粒接近热力学平衡形态的高质量金刚石膜,其中sp2碳相含量低于5.56%。分别采用激光拉曼光谱、扫描电镜与X射线衍射对金刚石膜的形核与生长进行研究。实验结果表明:在溅射有镍改性层的铜基底上,金刚石的形核密度比在无改性层的铜基底上的形核密度高10倍。镍改性层的增强机制主要来源于两个方面:镍改性层的纳米级粗糙表面增强金刚石籽晶颗粒的吸附;镍改性层的强催化效应加速铜基底上金刚石形核生长所需的石墨过渡层的形成,从而促进金刚石的快速形核。     

催化化学气相沉积法合成高纯束状碳纳米管（英文）

利用溶胶凝胶法合成了Co_(0.05)Mg_(0.095)MoO_4片状纳米催化剂,并以此采用催化化学气相沉积法以甲烷为碳源制备了束状碳纳米管。利用XRD、FESEM、TEM、HRTEM、TGA以及拉曼光谱等对合成的催化剂以及碳纳米管进行了表征,结果显示合成的碳管以束状形式存在。片状纳米催化剂对束状碳管的合成起到了至关重要的作用,碳管满足底端生长机制。金属Mo有利于碳管的形核,而受到单根碳管之间范德瓦尔斯力的作用,碳纳水管成束状生长,     

化学气相沉积法制备铼材料的研究进展

铼具有优异的物理力学性能,作为功能材料及超高温结构材料获得广泛应用。铼材料的制备方法有多种,化学气相沉积（CVD）是其主要的制备方法之一。本文简要介绍了化学气相沉积制备铼材料的反应类型、沉积条件及沉积效果,综述了CVDRe材料的沉积动力学、组织结构特征、力学性能的研究现状和典型应用,并与粉末冶金铼进行了对比分析。最后指出了目前CVDRe材料研究亟待解决的关键问题,并对进一步研究的方向和推广应用前景进行了展望。     

化学气相沉积纯钨材料晶体生长习性及其应用性能研究

本研究结合CVD(chemical vapor deposition,CVD)-W材料实际应用对其性能及组织结构的要求,详细讨论了随生长阶段的变化CVD-W晶体生长习性,获得了CVD-W表面形貌-晶粒生长尺寸-表面粗糙度三者与涂层厚度之间的关系,为CVD-W材料及技术在半导体行业及相关高温发热及防护领域中的应用和推广提供了借鉴。     

激光化学气相沉积(连载之三)

本讲座介绍了激光化学气相沉积的基本原理,较详细地讲述了制备金属薄膜、金刚石薄膜、类金刚石薄膜、氢化非晶硅薄膜、化合物半导体薄膜及绝缘体薄膜等所用的激光器、工艺参数以及薄膜的性能.     

激光化学气相沉积(连载之二)

介绍了激光化学气相沉积的基本原理,较详细地讲述了制备金属薄膜、金刚石薄膜、类金刚石薄膜、氢化非晶硅薄膜、化合物半导体薄膜及绝缘体薄膜等所用的激光器、工艺参数以及薄膜的性能.     

激光化学气相沉积(连载之一)

本讲座介绍了激光化学气相沉积的基本原理,较详细地讲述了制备金属薄膜、金刚石薄膜、类金刚石薄膜、氢化非晶硅薄膜、化合物半导体薄膜及绝缘体薄膜等所用的激光器、工艺参数以及薄膜的性能.     

改性海泡石作为循环使用的吸附剂在酸性溶液中吸附Pd(Ⅱ)的应用（英文）

研究以改性海泡石作为吸附剂从酸性溶液中回收Pd(Ⅱ)的吸附特性和机理;通过等温模型、动力学和热力学模型分析改性海泡石对Pd(Ⅱ)的吸附特性;利用SEM-EDS、TEM和XPS技术研究改性海泡石对Pd(Ⅱ)的吸附机理。Langmuir模型表明,当温度为30°C时,改性海泡石对Pd(Ⅱ)的最大吸附量为322.58 mg/g。动力学实验结果表明,准二级动力学模型能较好地模拟改性海泡石对Pd(Ⅱ)的吸附过程,化学吸附为改性海泡石吸附Pd(Ⅱ)的控速步骤。当Pd(Ⅱ)的初始浓度为100 mg/L时,1 g/L改性海泡石可吸附99%的Pd(Ⅱ)。吸附-脱附循环实验结果表明,改性海泡石具有良好的稳定性和重复使用性。本研究结果表明,改性海泡石是一种可高效且经济的Pd(Ⅱ)回收材料。     

Boron nitride coatings by chemical vapor deposition from borazine

Boron nitride coatings were prepared from borazine as the single source precursor containing stoichiometric boron and nitrogen by hot-wall chemical vapor deposition (CVD) in a low deposition temperature range from 800 °C to 900 °C, with a total pressure of 1 kPa. The chemical and phase compositions, morphologies and structures of the coatings were investigated. The coatings deposited at 800 °C still contained some residual N-H, whereas the coatings prepared at 900 °C were comparatively pure BN. The surface of the as-deposited coatings exhibited a pebble-like and compact structure, and the cross-sectional morphology of the coatings showed a laminar structure. While the as-deposited coatings had a turbostratic structure as evidenced from the XRD and TEM examinations, the turbostratic BN crystallized into hexagonal BN by heat treatment at temperatures above 1400 °C. The as-deposited coatings had a preferential orientation near the coating/graphite substrate interface in which the (002) basal planes organized parallel to the surface of the substrate.     

Direct deposition of CeO2 films on Ni metal substrate by chemical vapor deposition

Cerium dioxide thin films have been grown in-situ directly on cube textured Ni substrate by metal-organic chemical vapor deposition (MOCVD). At a lower deposition temperature of 400°C, an amorphous film was formed. The texture of crystalline CeO₂ film was changed from (200) orientation to (111) orientation when the deposition temperature was increased from 450°C to 550°C. The growth rate was ~40 nm/min and the rms surface roughness was 50 nm for the CeO₂ film deposited at 450°C for 10 min. Surface roughness of the film was increased with the development of (111) orientation. Deposited CeO₂ film showed a mixed texture of (100)<001> and (100)<011> orientation. Depending on the deposition condition, the transition from (100)<001> texture to (100)<011> orientation was observed.     

Linear and nonlinear optical spectra of polyazomethines fabricated by chemical vapor deposition

We report on the results of third-harmonic generation (THG) measurements on vapor-deposited thin films of two polyazomethines, poly(nitrilo-1,4-phenylenenitrilomethylidyne-1,4-phenylenemethylidyne) (PNPP) and poly(nitrilo-2,5-azinylnitrilomethylidyne-1,4-phenylenemethylidyne) (PNAP) covering pump energies from 0.6 to 1.4 eV. The THG data show the presence of a strong three-photon resonance centered near 0.9 eV for both samples; additional weaker structure is observed for PNPP near 1.2 eV. The peak values of the third-order susceptibility are 2.8 × 10⁻¹¹ e.s.u. for PNPP and 1.8 × 10⁻¹¹ e.s.u. for PNAP; off-resonance values are nearly an order of magnitude smaller. We have also obtained the χ⁽³⁾(3ω) spectrum of an oriented PNPP film grown on an obliquely evaporated SiO₂ pattern. An enhancement by nearly a factor of three in the peak nonlinear optical susceptibility is observed relative to that of the unoriented PNPP film, demonstrating that a moderate degree of molecular orientation was achieved.     

Preparation of carbon nanotubes and nano-particles by microwave plasma-enhanced chemical vapor deposition

Systematic preparation of carbon nanotubes (CNTs) and nanoparticles (CNPs) on Fe (or Co; Ni)/γ-Al₂O₃ by microwave plasma-enhanced chemical vapor deposition (MW-PECVD) has been reported with a mixture of CH₄, H₂, and Ar as precursors. By regulating the preparation parameters; Various carbon nanostructures including several novel CNTs have be obtained. The outstanding feature of this new approach is the low synthesis temperature (<520°C) due to the non-equilibrium characteristic of microwave plasma; Which is crucial for some practical applications. The experimental results also indicate the potentiality and feasibility for scaled-up production of CNTs and CNPs at low cost; And the posibility to control the morphologies and structures of the carbon products with MW-PECVD.     

Growth of straight carbon nanotubes by simple thermal chemical vapor deposition

Straight carbon nanotubes （CNTs） were achieved by simple thermal chemical vapor deposition（STCVD） catalyzed by Mo-Fe alloy catalyst on silica supporting substrate at 700 ℃. High-resolution transmission electron microscopy images show that the straight CNTs are well graphitized with no attached amorphous carbon. Mo-Fe alloy catalyst particles play a very crucial role in the growth of straight CNTs. The straight carbon nanotubes contain much less defects than the curved nanotubes and might have potential applications for nanoelectrical devices in the future. The simple synthesis of straight CNTs may have benefit for large-scale productions.     

Formation of mullite coatings on silicon-based ceramics by chemical vapor deposition

Dense, uniform, mullite coatings have been deposited by chemical vapor deposition on SiC substrates, using a AlCl₃-SiCl₄-CO₂-H₂ system. The typical coating microstructure consisted of a thin layer of nanocrystallites of γ-Al₂O₃ in vitreous silica at the coating-substrate interface, with columnar mullite grains over this interfacial layer. The composition of the coating was graded such that the outer surface of the coating was highly alumina rich. The changes in the coating microstructure with processing parameters are discussed. The ability of mullite to incorporate such large composition variations is discussed in the light of vacancy formation as theAl/Si ratio is increased and the ordering of these vacancies leads to changes in lattice parameters. The formation of domains was studied by measuring the spacing of superlattice spots in electron diffraction patterns and the relationship between domain size andAl/Si ratio is discussed.