ICP-OES测试给水用聚乙烯(PE)管材中铁、钙含量的方法研究

本文选取给水用聚乙烯(PE)管材样品为研究对象,采用电感耦合等离子体发射光谱法(ICP-OES)测试铁、钙元素的含量,重点对样品的前处理方法进行了对比分析,对于铁、钙这类不挥发性的元素的测定,直接用干法灰化法较微波消解法更能使样品快速消解完全,而且能有效避免被测元素的损失,又能快速定量测定样品中的非挥发性元素,快速有效。     

纳米粒子在气体流动中的团聚过程研究

采用气相合成法制备纳米微粉时，由反应合成区生成的纳米微粒在随气流流向收集装置的过程中，因相互碰撞、粘附而发生团聚现象，形成较大的颗粒。本文论述了团聚现象发生的原因，借用气体分子动力学理论，计算了纳米粒子在气体流动中的团聚过程，得到了粒子直径、质量、体积、微观热运动速度及空间密度的沿程分布函数。     

离子型γ-Fe_2O_3/Ni_2O_3磁性液体的制备、磁化性质和微结构特征

用Massart法合成了水基γ-Fe_2O_3/Ni_2O_3复合纳米微粒多分散离子型磁性液体。该磁性液体的磁化强度和光透射驰豫现象表明磁性液体中除了存在无环的微团聚外,还有链状团聚。由于在多分散磁性液体中,磁性微粒之间的磁相互作用很弱,仅靠磁相互作用不能形成链状团聚体,链状团聚体的形成是受到了"排空力"的作用。在γ-Fe_2O_3/Ni_2O_3离子型磁性液体中,"排空力"促使液体中的较大微粒在无外磁场作用下形成短链,磁性液体的宏观特性如磁化强度和光弛豫现象都是由这些短链造成的。同时,只具有链状团聚体的磁性液体具有优良的磁光效应。     

纳米粒子在气体流动中的团聚过程研究

采用气相合成法制备纳米微粉时，由反应合成区生成的纳米微粒在随气流流向收集装置的过程中，因相互碰撞，粘附而发生聚现象，形成较大的颗粒，本论述了团聚现象发生的原因，借用气体分子动力学理论，计算了纳米粒子在气体流动中的团聚过程，得到了粒子直径，质量，体积，微观热运动速度及空间密度的沿程分布函数。     

初始原料和球磨气氛对ODS铁素体钢机械合金化的影响

分别采用纯金属粉和氮气雾化预合金粉作为机械合金化的初始原料,对它在球磨过程中的合金化效果、粉末形貌、粒度分布和过量氧含量的影响进行对比.结果表明:当使用雾化合金粉作为初始原料,球磨后合金元素的分布比采用纯金属粉为原料更加均匀.使用高纯氩气作为保护气氛比真空球磨更能有效减少合金粉末中的过量氧含量.     

Ag-TCNQ金属/有机双层膜中的扩散机制

研究了用真空分层蒸镀法获得的金属/有机双层膜(Ag-TCNQ)中的层间扩散行为.根据Cu、Ag在与TCNQ形成络合物时表现出的相似性,建立了异质元素标志法,以Cu为标志元素,研究了金属有机络合物Ag-TCNQ形成过程中Ag扩散的微观机制.使用二次离子质谱(SIMS)分析了Cu、Ag元素在不同样品膜中的浓度分布及变化情况.结果表明,不同于纯金属薄膜中Cu、Ag清晰的界面,在络合物中的Cu与Ag之间存在交叉,说明两种离子之间存在着交换现象.由此可以推断,薄膜中的扩散机制是Ag离子在Ag-TCNQ络合物中的换位扩散.     

玩具涂层中可迁移元素及塑料总铅含量测定的前处理方法

本文通过对磁性涂层在过筛、加入乙醇等因素下进行可迁移元素溶出性实验,结果表明过筛和加入乙醇这种预处理方式,能够使可迁移元素的溶出量明显增加,尤其是可迁移元素Se;另外对两组标准样品,采用干法灰化和微波消解法两种不同前处理方式进行处理,微波消解回收率分别能达到85％、87％,而干法灰化只有65％和60％的回收率.微波消解...     

3种不同前处理方法测定卤粉中铅含量的比较研究

比较3种不同前处理方法对卤粉中铅含量测定结果的影响。分别采用微波消解、湿法消解、干法灰化对样品进行前处理,采用石墨炉原子吸收法测定。微波消解耗时短,酸用量小,回收率较好。湿法消解耗时长,酸用量比较多,回收率较高。干法灰化耗时较长,酸用量小,由于灰化温度较高,元素有一定损失,回收率偏低。3种前处理方法均适用于卤粉中铅含量的测定。其中微波消解耗时短,酸用量小,回收率较好,是一种比较好的方法。     

RF磁控溅射法制备ZnO薄膜的XRD分析

采用RF磁控溅射法，在玻璃村底上制备多晶ZnO薄膜，并对所制备的ZnO薄膜在空气气氛中进行了不同温度（350～600℃）的退火处理和600℃时N2气氛中的退火处理。利用X射线衍射分析了溅射参数如溅射功率、溅射氧分压、衬底温度以及退火处理对ZnO薄膜结晶性能的影响。结果表明，合适的衬底温度和退火处理能够提高ZnO薄膜的结晶质量。     

基于柠檬酸铁的介孔碳材料的制备及电化学研究

以柠檬酸铁为原料,采用直接碳化法,制备出介孔碳材料。通过SEM和TEM对其形貌进行分析,发现样品具有大量的孔道结构。N2吸附测试表明,所制备介孔碳MCs-800的比表面积高达1 918m2/g。采用TG技术研究了柠檬酸铁在氮气气氛中的热解过程。并用循环伏安法和恒电流充放电法进行电化学测试。测试表明,以柠檬酸铁为原料碳化所得的介孔碳的循环伏安图形接近矩形,在恒电流充放电过程中发现样品在不同的电流密度下均呈现出较规则的三角形,且阳极和阴极过程基本对称,表明样品具有良好的电化学稳定性和可逆性。     

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.     

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.……     

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...     

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.     

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.     

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 ...