超声辅助湿法合成纳米HA及MWNT/HA复合材料

以Ca(NO3)2·4H2O、(NH4)2HPO4和NH3·H2O为原料,在超声波辅助下,湿法合成了羟基磷灰石,用FTIR、XRD和TEM对产物进行了分析,结果表明:合成的羟基磷灰石为纳米级纺缍状晶体,不用烧结即具有较高晶化度,且为单一的羟基磷灰石晶相。以此制备条件为基础,采用原位合成的方法制备了多壁碳纳米管/羟基磷灰石复合材料,FTIR、XRD和TEM的分析结果表明:碳纳米管能较好的分散于羟基磷灰石基体中,部分碳纳米管表面可被反应生成的羟基磷灰石所包覆,二者之间有着较好的相容性,可作为一种新型的生物复合材料应用。     

碳纳米管对炭纤维/聚碳酸酯复合材料界面结合性能的影响

为改善炭纤维和聚碳酸酯界面结合性能,制备了含碳纳米管的水性聚碳酸酯上浆剂和水性聚氨酯上浆剂,通过上浆工艺将碳纳米管引至炭纤维表面.分别采用单丝段裂法和定向纤维增强聚合物基复合材料垂直方向拉伸两种方法从微观和宏观两个角度研究了上浆剂种类及碳纳米管含量对复合材料界面结合性能的影响.结果表明:上浆剂可明显改善炭纤维/聚碳酸酯...     

阵列式碳纳米管对聚苯胺导电性能影响

用原位聚合法制备了聚苯胺／碳纳米管复合材料，研究了碳纳米管加入时间、搅拌速度等工艺因素对复合材料导电性能的影响。用四极电子电位差计和HT600透射电子显微镜对该复合材料的导电性能和微观形态作了检测。试验结果表明：在原位复合条件下，聚苯胺可以完全包覆在碳纳米管上，而且碳纳米管在聚苯胺基体中呈网状分布，使复合材料的导电性能得到改善。     

镀钴碳纳米管的制备及其电磁特性

在碳纳米管表面镀覆磁性金属粒子,可获得电磁性能优异的复合材料.对碳纳米管进行预处理,再用化学镀法在其表面包覆钴金属制备碳纳米管-维复合材料.用透射电子显微镜(TEM)、能谱仪、振动样品磁强计、矢量网络分析仪分析了复合材料的形貌、成分及电磁性能,并研究了化学镀工艺对镀层沉积速率的影响.结果表明:镀覆后碳管表面包覆了一层钴...     

离子液体为溶剂制备纤维素／单壁碳纳米管复合物

用溶于离子液体[BMIM]Br中的纤维素功能化单壁碳纳米管,制备了水溶性的纤维素/碳纳米管复合材料.HR-TEM,FE-SEM,元素线扫描分析结果表明:纤维素成功包覆在单壁碳纳米管的表面,包覆层厚度约2～4nm.拉曼光谱分析进一步证明纤维素包覆碳纳米管的驱动力是非共价力.     

锶铁氧体包覆碳纳米管吸波材料的制备及表征

采用溶胶-凝胶法制备锶铁氧体包覆碳纳米管(CNTs)的吸波材料,并考察了碳纳米管含量对包覆后样品磁性能及吸波性能的影响.经TEM、XRD验证锶铁氧体成功地包覆在碳纳米管表面;ALVSM图中可以看出6%CNTs-SrFe11.5O19的磁性能最佳,矫顽力(Hc)为5916.13Oe.而经网络分析仪测定,5% CNTs-S...     

聚甲基丙烯酸甲酯与纳米Fe3O4的复合研究

将用共沉淀法合成的包覆油酸的Fe3O4纳米粒子,分散在甲基丙烯酸甲酯(MMA)中,采用原位聚合法制备得到PMMA/Fe3O4纳米复合材料,研究了Fe3O4含量对复合材料的玻璃化转变温度(Tg)、溶解性能以及复合材料中PMMA分子量的影响.实验结果显示:复合材料的Tg较纯PMMA有所提高,且随着Fe3O4含量的增大而增高...     

氨基化二氧化硅包覆碳纳米管增强环氧树脂复合材料

本文制备了二氧化硅包覆的碳纳米管,并在其表面引入氨基,从而获得在环氧树脂基体中分散性良好的化学修饰的碳纳米管。首先通过强碱醇溶液处理碳纳米管,制备羟基化碳纳米管(MWNTs-OH),然后将MWNTs-OH分散于乙醇溶液中,加入正硅酸乙酯(TEOS),通过Stber法制备了表面包覆二氧化硅的碳纳米管(MWNTs-SiO2);将MWNTs-SiO2进一步与氨丙基三乙氧基硅烷反应,得到氨基化二氧化硅包覆碳纳米管(MWNTs-SiO2-NH2)。将所制备的MWNTs-SiO2-NH2与缩水甘油醚型环氧树脂E-44复合,并以三乙醇胺为固化剂,得到氨基化碳纳米管/环氧树脂复合材料。实验结果表明,碳纳米管表面成功地引入了氨基基团;表面氨基化碳纳米管在环氧树脂基体中的分散性得到了显著的提高,同时氨基化碳纳米管能够显著地提高复合材料的冲击强度和拉伸强度。     

碳纳米管/四氧化三铁复合材料的电磁波吸收性能(英文)

采用水热法制备碳纳米管(MWCNT)/四氧化三铁(Fe3O4)复合材料,运用透射电子显微镜、X射线衍射仪、振动样品磁强计及网络矢量分析仪等,对复合材料的微观结构、磁性能及电磁波吸收性能(8.2～12.4 GHz,X波段)进行研究和分析。结果表明,磁性Fe3O4纳米颗粒能够较好地包覆在MWCNTs表面上,并且随着反应混合液中Fe2+和Fe3+浓度的增加,MWCNT/Fe3O4复合材料中的Fe3O4含量增加,MWCNT/Fe3O4复合材料的磁性能增强;当反应混合液中的Fe2+和Fe3+的浓度分别为0.02和0.04 mol/L时,MWCNT/Fe3O4复合材料的电磁波吸收性能最佳,具体表现为吸收峰峰值最低,吸收频宽最宽。     

聚碳酸酯/无机纳米复合材料的研究进展

综述了聚碳酸酯(PC)/无机纳米复合材料的最新研究进展,分别介绍了零维无机纳米粉体、一维碳纳米管与二维层状纳米材料与PC复合材料的制备技术及其性能研究,并对聚碳酸酯/无机纳米复合材料的发展方向进行了展望。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...