石墨烯微片表面沉积亚微米金属镍合金颗粒

目的 利用金属粒子对石墨烯表面进行金属改性,以改善其吸波特性、复合材料界面和润湿性等,并且在保证石墨烯与金属粒子本身的特性基础上,还能产生另外的协同效应。方法 采用水热法将亚微米级的Ni金属颗粒沉积在物理法剥离的石墨烯微片表面上,并采用XRD, EDS, SEM, TEM等测试手段进行改性复合粉体的微观表征。结果 预处理工艺可以大大优化改性效果,使金属颗粒沉积更加均匀;最佳水热工艺为水热180 ℃,反应2 h,石墨烯微片负载量为2.5 g/L;微观表征结果显示,实际沉积的金属颗粒为Ni-P合金,分散的Ni-P合金粒径约为200 nm,在沉积过程中可形成团聚的约2 μm金属颗粒堆积,并分布于石墨烯微片表面。结论 水热法可以成功地将镍颗粒均匀地沉积在石墨烯微片表面上,从而实现石墨烯表面的金属改性。     

消失模铸造工艺表面合金化机理研究

利用消失模铸造工艺,通过正交实验合金化工艺,重点研究了表面合金化的形成机理,建立了消失模铸件表面合金化模型,分析了合金化过程的动力。在不同真空度、金属粒度、温度为780℃的条件下进行浇注,发现在镁合金基体表面形成均匀的合金化层,通过扫描电镜(SEM)分析表层组织变化,对生成的新相进行微区成分和表层线成分分析。研究表明,在表层生成的新相主要是Mg17Al12,并且表层显微硬度明显高于基体。分析了合金化机理和影响形成均匀合金化层的主要因素,得出了合金化颗粒粒度和铸渗动力在合金化过程中起关键作用,随着合金化颗粒粒度和真空度增大,表面合金化效果明显得到了提高。     

急冷凝固FGH96合金粉末颗粒表面成分及预热处理对凝固组织的影响研究

对氩气雾化（AA）FGH96合金不同粒度急冷粉末颗粒表面进行俄歇电子能谱（AES）分析,对不同温度下进行预热处理粉末中碳化物的演变行为进行了研究,并讨论了粉末颗粒表面成分和预热处理时碳化物变化和转变的关系。结果表明：不同粒度FGH96合金原始粉末颗粒表面存在不同厚度C、O和Ti元素的污染层;经预热处理,粉末颗粒中MC＇型亚稳碳化物发生分解和转变,析出稳定MC、M23C6及M6C型碳化物,明显改变粉末颗粒内碳化物的稳定性和分布状态。     

洁净系统中激光诱导颗粒污染物的分析与评估

高功率激光系统要求在洁净环境中运行,若光学元件表面在工作过程中附着污染物,将导致光学元件的损伤及整个系统负载能力的下降。针对洁净系统中激光与材料作用而产生的颗粒物,分析其作用机制,探讨用于评估的理论依据,讨论测量的需求和方法,并对系统表面存在的颗粒污染物进行了实际测量分析,提出了深入开展高功率激光系统中颗粒污染物测量与评估的技术途径。     

生物模板法制备具有特殊表面形貌的二氧化硅中空微球

利用油菜花粉作为生物模板,通过溶胶在花粉颗粒表面包裹,再经高温烧结去除花粉颗粒的方法制备了具有特殊表面形貌的二氧化硅中空微球. 并通过调节溶胶中醇盐与水的比例,实现了不同表面形貌的二氧化硅中空微球的制备. 利用差热（DSC）、热重（TG）、X射线能谱仪（EDS）、扫描电子显微镜（SEM）等对花粉颗粒和所制备的二氧化硅中空微球进行了表征,并对不同表面形貌的形成机理进行了探讨. 结果表明,花粉内壁在200℃时即可完全消除,从而形成中空结构,而外壁及其表面的网格状结构在较高温度仍能保持完好,从而保证该结构在微球表面的复制,而溶胶浓度则是形成微球表面不同形貌的决定因素,随着胶体粒子在花粉表面沉积量的不同,微球表面的微孔结构也将随之变化.     

低能Ar^＋离子溅射合金表面组份变化的俄歇电子谱研究

用 AES分析了 AgCu、NiCr 合金受低能 Ar~+离子轰击后表面组份的变化,通过俄歇低能峰(LAES)和俄歇高能峰(HAES)的分析发现,离子轰击使合金表面组份达到相对稳定时,停止轰击后表面成分在短时间内有一个变化。离子轰击引起表面成分的变化发生在表面外层和以下数层内。随着轰击离子能量和束流密度的变化,表面最外层成分处于相对稳定和饱和的趋势,而亚表层内成分随之变化。对此,估算了这种变化对 AES 定量分析的影响,并对离子轰击诱导表面偏析和增强扩散效应进行了讨论。     

某ZTA15钛合金零件铸造表面质量异常分析

目的 以铸造表面存在黑色斑点的某ZTA15钛合金零件为研究对象,研究零件铸造表面外来物质的成分、结合方式及其形成原因。方法 利用扫描电子显微镜对零件铸造表面及截面形貌进行观察,利用能谱分析仪对零件铸造表面及截面成分进行分析。结果 零件铸造表面主要存在棕刚玉颗粒和碳黑颗粒两种外来物质,棕刚玉颗粒嵌入铸件基体,碳黑颗粒附着于铸造表面。结论 零件铸造表面黑色斑点是碳黑颗粒显示,附着于铸造表面的碳黑颗粒对零件表面质量及镀层质量有影响,碳黑颗粒产生于零件表面油污清洗不洁净真空热处理后析出,热处理前采用超声波清洗+冷水洗+热水洗+吹干的方法清洁零件,可改善零件热处理后的表面质量。     

多孔颗粒材料内孔表面分维测算及与保水性能的关系

为考察多孔颗粒材料内孔表面分形特征及与其保水性能的关系,构建了多孔颗粒物内孔表面分维测算数学模型,并基于高精度扫描电子显微镜系统测算了4种多孔颗粒样品的内孔表面分维,测量了材料保水性能。结果表明:多孔颗粒的内孔表面的分维值介于2.088 2~2.193 5之间,且分形拟合曲线相关系数大于0.98,强的相关性说明内孔表面具有显著的分形特征。进一步研究发现,多孔颗粒材料保水性能与其内孔表面分维呈负相关。     

油酸修饰自修复添加剂在金属摩擦副表面成膜过程研究

采用油酸对蛇纹石粉体进行表面修饰,使用红外光谱仪(IR)和X射线衍射仪(XRD)分析了它对粉体的分散机理.使用MM200摩擦磨损试验机研究金属摩擦副在含有自修复添加剂的润滑油润滑下的成膜过程,借助SEM及EDAX测试分析自修复膜层的表面形貌及表面成分组成.结果表明,油酸可以很好的使粉体分散于润滑油中,其作用机理为油酸与粉体表面的羟基发生酯化反应.当摩擦磨损时间很短时摩擦副表面就可出现自修复膜层,但成膜过程和磨损过程同步进行,随着时间的增加,膜层的形成愈来愈稳定,直至覆盖整个金属磨损表面.其成膜机理为,在摩擦过程中,两接触表面上的微凸体对粉体的研磨作用使粉体粒子表面带有大量的悬挂键,同时接触的金属摩擦副也形成活化表面,从而使粉体颗粒吸附在金属表面.在载荷的作用下,粉体颗粒在磨损表面铺展形成自修复膜.     

航空液压油固体颗粒污染度的测定与分级

飞机液压系统工况的监测及其故障的预测都要参照航空液压油污染度这一指标,航空液压系统出现的故障多是由污染,尤其是固体颗粒污染造成的,因此,对航空液压油固体颗粒污染度进行测定及分级,有利于保障航空飞行的安全性和稳定性。本文基于航空液压油污染物来源、种类及危害,对存在的固体颗粒污染问题进行分析,并介绍了相关的测定方法和评定标准。     

Quality of hemodialysis water in a resource‐poor country: The Nigerian example

Hemodialysis (HD) patients are exposed to large volumes of water, separated from patients' blood by semipermeable membrane of dialyzers. Chemical contaminants in poorly treated water impact negatively on quality of life of these patients. This survey was carried out to assess the HD water quality in Lagos, Nigeria. Ten milliliters of feed and treated water from all six HD centers in Lagos were tested for aluminum, copper, zinc, magnesium, calcium using atomic absorption spectrometry; sodium and potassium were tested using flame photometry, fluoride with molecular photoluminescence method; sulfate using turbidimetry, nitrates measured by cadmium column reduction method, chloramines and free chlorine were measured using N, N‐diethyl‐1‐P‐phenylenediamine colorimetric method. Information on sources of feed water, frequency of testing of HD water, methods of water treatment, type of water purification system and maintenance was also obtained. All centers used borehole as main source of water supply. None of the centers met Association for the Advancement of Medical Instrumentation (AAMI) guidelines for most chemical contaminants. Only chlorine (0.48 ± 0.07 mg/L) and potassium (3.9 ± 0.95 mg/L) levels met AAMI standards after treatment. Mean levels of chemical contaminants in treated water were as follows: aluminum 0.04 ± 0.01 mg/L, zinc 0.27 ± 0.08 mg/L, chloramines 0.16 ± 0.03 mg/L, fluoride 1.83 ± 0.40 mg/L, sulfate 117 ± 86.1 mg/L which were mildly elevated; calcium 126.00 ± 22.7 mg/L, sodium 179 ± 25.6 mg/L, and nitrate 70.5 ± 50.8 mg/L, which were markedly elevated; and magnesium 8.3 ± 3.38 mg/L, which was moderately elevated above AAMI recommended levels. HD water quality is poor in our environment. Concerted efforts are required to ensure good quality water for HD.     

A Force‐Engineered Lint Roller for Superclean Graphene

Contamination is a major concern in surface and interface technologies. Given that graphene is a 2D monolayer material with an extremely large surface area, surface contamination may seriously degrade its intrinsic properties and strongly hinder its applicability in surface and interfacial regions. However, large‐scale and facile treatment methods for producing clean graphene films that preserve its excellent properties have not yet been achieved. Herein, an efficient postgrowth treatment method for selectively removing surface contamination to achieve a large‐area superclean graphene surface is reported. The as‐obtained superclean graphene, with surface cleanness exceeding 99%, can be transferred to dielectric substrates with significantly reduced polymer residues, yielding ultrahigh carrier mobility of 500 000 cm² V^?1 s^?1 and low contact resistance of 118 Ω µm. The successful removal of contamination is enabled by the strong adhesive force of the activated‐carbon‐based lint roller on graphene contaminants.     

Nanomaterial‐enabled Rapid Detection of Water Contaminants

Water contaminants, e.g., inorganic chemicals and microorganisms, are critical metrics for water quality monitoring and have significant impacts on human health and plants/organisms living in water. The scope and focus of this review is nanomaterial‐based optical, electronic, and electrochemical sensors for rapid detection of water contaminants, e.g., heavy metals, anions, and bacteria. These contaminants are commonly found in different water systems. The importance of water quality monitoring and control demands significant advancement in the detection of contaminants in water because current sensing technologies for water contaminants have limitations. The advantages of nanomaterial‐based sensing technologies are highlighted and recent progress on nanomaterial‐based sensors for rapid water contaminant detection is discussed. An outlook for future research into this rapidly growing field is also provided.     

不同电源等电位离子钨钼共渗的研究

利用脉冲单电源和直流单电源,分别在Q235钢表面进行等离子钨钼共渗.通过对不同电源钨钼共渗试样的渗层组织、渗层成分分布、晶体结构、渗层硬度分布的检测和比较,分析了2种电源对等离子钨钼共渗的影响.结果表明,利用单一电源均可在Q235钢表面形成明显反应扩散层;在相同工艺下,采用脉冲电源所得到的试样渗层厚度较采用直流电源的渗层厚度增加了18.1%;脉冲电源试样表面W、Mo含量(质量分数,下同)分别约为8.4%和9.8%,直流电源试样表面W、Mo含量分别为8.2%和8.9%,可见2种电源渗层表面含W、Mo量相差不大;2种电源渗层相结构均为Fe_7W_6和Fe_3Mo金属间化合物相;钨钼共渗后渗层硬度提高不明显.     

新装修住宅室内微污染物的测试与分析

随着人们的生活质量的提高,室内空气品质成为人们关注的热点,为把握目前新装修住宅室内空气污染现状,提高室内空气质量,提供构筑室内空气微污染物对策的基础依据,对某市新装修住宅室内空气进行了实地测试.根据某市20户新装修住宅室内微污染物种类及浓度现场测试和问卷调查结果,分析了新装修住宅室内污染物的状况,研究了影响微污染物浓度高低的主要因素.     

Green synthesis of bentonite/cellulose@lead oxide bio-nanocomposite with assistance of Pistacia Atlantica extract for efficient photocatalytic degradation of ciprofloxacin

In this study, a novel bentonite/cellulose@lead oxide (BT-CL-PbO) bio-nanocomposite was synthesized via a green route. For this proposal, the extracted cellulose from barley waste and natural bentonite were bonded together by covalent bonding, and finally the biosynthesized lead oxide nanoparticles were immobilized on them. Then, due to the destructive impacts of antibiotic contaminants on the environment and ecosystem, the catalytic activity of nanocomposite was investigated for the photodegradation of ciprofloxacin. The BT-CL-PbO exhibited excellent catalytic activity over CIP degradation under sunlight. Effect of initial pH, ciprofloxacin concentration, BT-CL-PbO dosage, and the existence of anions on photocatalytic activity was studied. The photodegradation process of CIP fitted the pseudo-first-order kinetic model, and the rate constants in the presence of BT-CL-PbO reached 0.1309 min^?1, which was about 2.3 times higher than that of bare PbO nanoparticles. The scavenging experiments confirmed that photoexcited holes (h⁺) played the prominent role in the photodegradation of CIP. The BT-CL-PbO showed high stability and reusability after three cycles of photodegradation. The obtained results found that the BT-CL-PbO is a cost-effective and recyclable photocatalyst for the photodegradation of CIP and can be used for the treatment of other pharmaceutical contaminants.     

Studies on the development of a quick inertness test procedure for multi-use PET containers—sorption behaviour of bottle wall strips

This study is part of a larger project aimed at establishing criteria to ensure the quality and safety-in-use of recycled and re-used plastics for food packaging. A major concern is that plastic materials can interact with chemicals to a greater or lesser extent. As a consequence, refillable containers may be contaminated by migration of harmful substances into the plastic material due to misuse by consumers before return. On the other hand, there is currently neither any specific national or EU regulation nor a standard test available which could be applied by industry or enforcement laboratories to meet this situation appropriately. In this study, a relative simple inertness test which focuses on the interaction of PET bottle wall strips with a selection of model contaminants was investigated. The model contaminants were selected to include four different sets of chemical functional classes (set A, alcohol-type compounds; B, ester/ketone type compounds; set C, hydrocarbon-type compounds; set D, chlorinated hydrocarbons). A simple gas chromatographic method using flame ionization detection was developed to allow quantification of the whole range of model contaminants. Linearity and reproducibility of the calibration curves for all contaminants were excellent, which indicates the validity and efficacy of the proposed methodology. The sorption experiments with PET bottle wall strips showed that significant amounts of chemicals can be absorbed into the plastic material if misused, thus establishing a remigration potential in the bottle material after refilling. © 1997 John Wiley & Sons, Ltd.     

Splitting and unidirectional excitation of surface plasmon polaritons by two uniform metallic nanoslits with a nanocavity antenna

A tunable splitter and source of surface plasmon polaritons (SPPs) is proposed. The structure is composed of two Ag films, with two uniform nanoslits fabricated in the lower Ag film and lying above is a movable Ag film. By changing the horizontal position of the top Ag film, the splitting ratio of the SPPs varies periodically based on SPP interference. The field distribution of the structure is investigated by using the finite-difference time-domain (FDTD) method. The period obtained by the FDTD agrees well with the Fabry–Pérot cavity model. When the SPP splitting ratio is large (or small), our structure acts as a low noise SPP source. Compared with other SPP sources, our model possesses better directionality.     

Carbon buffer layers for smoothing superpolished glass surfaces as substrates for molybdenum /silicon multilayer soft-x-ray mirrors

Zerodur and BK7 glass substrates (developed by Fa. Glaswerke Schott, D-55014 Mainz, Germany) from Carl Zeiss Oberkochen polished to a standard surface roughness of varsigma = 0.8 nm rms were coated with a C layer by electron-beam evaporation in the UHV. The roughness of the C-layer surfaces is reduced to 0.6 nm rms. A normal-incidence reflectance of 50% at a wavelength of 13 nm was measured for a Mo/Si multilayer soft-x-ray mirror with 30 double layers (N = 30) deposited onto the BK7/C substrate, whereas a similar Mo/Si multilayer (N = 30) evaporated directly onto the bare BK7 surface turned out to show a reflectance of only 42%.     

800MeV储存环超高真空系统数据计算机监测系统

介绍了国家同步辐射实验室800MeV储存环真空数据计算机监测系统，并对其硬件结构和软件部分作了简述。该系统自开始使用至今已5年多，运行情况良好。记录了真空系统的大量真空数据，为电子储存环机器的运行、束流寿命研究和故障的分析、处理提供了可靠的依据，很好地满足了设备使用的要求。