热阴极DC-PCVD方法制备的金刚石厚膜的生长特性和内应力

采用热阴极DC PCVD(DirectCurrentPlasmaChemicalVaporDeposition)方法制备出大尺寸高质量的金刚石厚膜,研究了金刚石厚膜的生长特性和内应力状态。由热阴极DC PCVD方法制备的金刚石厚膜大多数为〈110〉取向,表面显露面主要是(100)面和(111)面,厚膜的表面被较多的孪晶所覆盖,部分(111)面退化为3个相互垂直的(110)面,孪晶使厚膜表面结晶特性复杂化,金刚石厚膜的晶粒沿生长方向呈现柱状生长。金刚石厚膜的生长速率随甲烷流量和工作气压的增加而增加,但随生长速率的提高金刚石膜的品质明显下降。金刚石厚膜的内应力以压应力为主,随着甲烷浓度的增加压应力增加,随着工作气压的增加压应力减小,到某个气压之后变为张应力。     

微波PCVD法大尺寸透明自支撑金刚石膜的制备及红外透过率

采用微波PCVD方法制备出直径50mm膜厚300um的大尺寸透明自支撑金刚石膜.在甲烷体积分数2%的条件下制备的透明自支撑金刚石膜经过两面抛光后在500cm-1-4000cm-1红外波段范同内红外透过率达到70%,但是其生长速率只有1um/h-2um/h.在体积分数4%甲烷浓度下制备的自支撑透明金刚石膜,其生长速率达到7um/h～8um/h,经过两面抛光之后膜厚为260um的金刚石膜的在500cm-1～4000cm-1红外波段范围内红外透过率达到60%左右,而且膜中心和边缘区的红外透过率基本相同.这些结果为大尺寸金刚石厚膜在红外窗口上的实际应用奠定了基础.     

基体温度对金刚石厚膜沉积质量的影响

为探讨燃焰法沉积高质量金刚石厚膜的可能及其沉积速率，在反应气体流量比O2／C2H2=0．97～1范围内，研究了基体温度对燃焰法沉积金刚石厚膜的影响．结果表明，基体温度在610～730℃范围内可沉积出均匀、致密、结晶形态优良的金刚石厚膜；金刚石厚膜沉积速率随基体温度的下降而下降，基体温度约为730℃时，可以约50μm／h的较高速率沉积出淡黄色透明状高质量金刚石厚膜．当基体温度在820℃左右的高温时，金刚石厚膜不均匀，晶粒间存在较大间隙，且在金刚石厚膜生长过程中，存在较多的二次成核。     

CVD金刚石膜产业化制备技术研究

为了解决化学气相沉积金刚石膜产业化进程中存在的生长速率慢、沉积尺寸小的难题,自行研制了适宜于大尺寸金刚石膜高速生长的电子辅助热灯丝式化学气相沉积(EAHFCVD)装置,通过反应气体中加氧将碳源浓度提高到10%以上,并优化反应压力与直流偏流密度二参数间的匹配,研究了该装置的生产特性,同时利用SEM、XRD和Raman光谱对沉积的金刚石膜进行了分析表征.研究结果表明,应用该装置高质量金刚石膜的沉积尺寸可达100mm以上,生长速率达到约10μm/h的水平,并制备出100mm×1 5mm的完整金刚石自支撑膜片,该技术可满足产业化生产的要求.     

低成本高质量金刚石膜生长技术及热学方面的应用

随着大功率电子、光电子、微波器件以及超大规模IC技术的飞速发展,急需新的热沉材料,用高导热高绝缘金刚石膜代替目前常用的热沉材料,具有广阔的应用前景和市场容量。现在的问题是建立和发展低成本大尺寸高导热金刚石膜的制备技术,解决与热沉应用相关的关键技术。 几年来,在国家“八六三”计划的支持下,建立和发展了直流热阴极PCVD,EA-CVD和微波PCVD等高质量金刚石膜的制备技术。用直流热阴极PCVD和EA-CVD方法制备出大尺寸高导热金刚石厚膜,沉积尺寸为φ80mm,膜厚最高达到4.2mm,     

间歇生长模式高甲烷浓度制备纳米金刚石膜

采用直流热阴极PCVD技术,经过生长温度的周期性调整,达到清除多余游离碳和刻蚀非金刚石相的目的,实现了在高甲烷浓度条件下制备纳米金刚石膜.金刚石膜的生长过程分为沉积阶段和刻蚀去除阶段,沉积时间为15min,刻蚀时间为5min,生长周期为20min,总的沉积时间为6h.采用拉曼光谱仪、SEM和XRD分析仪对样品进行了分析,结果显示样品具有纳米金刚石膜的基本特征.研究表明,在高甲烷浓度条件下,直流热阴极PCVD间歇生长模式可有效去除生长腔内的游离碳成分,实现正常放电激励,维持正常生长,制备出纳米金刚石膜.     

热阴极辉光放电对金刚石膜沉积的影响

研究了在热阴极辉光放电等离子体化学气相沉积金刚石膜过程中，热阴极辉光放电特性与金刚石膜沉积工艺的关系．结果表明，适当的阴极温度是保证大电流、高气压辉光放电的必要条件．阴极的温度影响辉光放电阴极位降区的放电性质．金刚石膜的沉积速率随着气体压力(16～20kPa)的升高而上升，在18.6kPa左右出现最高值，而阳极位降区电场强度的降低使膜品质下降．放电电流(8～12A)对沉积速率的影响与气体压力的影响具有相似的规律．     

直流等离子体CVD法金刚石薄膜的Raman谱和内应力研究

本文给出了直流等离子体CVD法合成金刚石膜的实验结果。衬底温度900℃时,在Si(100)上最高生长速率为150μm/h。实验结果表明金刚石膜Raman特征峰随生长时间和晶粒增大移向低波数方向,这主要是膜内应力所致。Raman谱还表明金刚石膜内非晶碳成份随放电电流密度和生长时间增加而减少,并主要集中在晶粒界面之间。文中还对高速率生长金刚石膜的机理及内应力形成的原因进行了讨论。     

CVD金刚石膜在微波管中的应用

金刚石由于其低的介电常数、高的导热率和优良的机械性能 ,将其应用于微波管改善其散热性能取代传统有毒的氧化铍陶瓷 ,是微波管螺旋线优良的支撑材料。本文首次采用等离子体化学气相沉积法在行波管夹持杆上沉积金刚石厚膜 ,经材料和慢波组件性能测试 ,获得了较好的实验结果 :导热率 12W/cm·℃ ,介电常数为 5 .0～ 5 .3,介质损耗为 1× 10 -3 ,体积电阻率约 10 13 Ω·cm ;慢波组件导热性能与同结构的BeO组件相比提高 3.0倍。表明该薄膜能满足大功率行波管的设计、工艺技术要求     

热丝法化学气相沉积金刚石膜

用热丝法沉积金刚石膜,分离送入氢气和甲烷,可以减少钨丝碳化,提高功率利用率.分送与混送相结合,可以制备晶体形态良好的金刚石膜.到达基材表面的活性粒子的数量是提高金刚石膜生长速率的关键.生长速率可达3.8μm/h,均匀区面积达400mm2.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.