用软化学过程制备高性能片式电感材料

通过软化学过程-凝胶自然烧和柠檬酸络合法合成高活性铁氧体纳米微粉或先驱体。 实现了无助烧剂Ni-Zn-Cu铁氧化的低温烧结,解决了平面六角结构铁氧体的纯相合成和低温烧结技术难题,研制出两大类具有细晶显微结构特征的高磁导率低温烧结Ni-Zn-Cu铁氧体和平面六角结构软磁氧体材料。     

Ir4+掺杂Co2Z平面六角软磁铁氧体的磁性能

采用普通陶瓷工艺制备了Ir4+掺杂的Co2Z型平面六角铁氧体,研究了少量Ir4+掺杂对Co2Z型铁氧体材料结构和磁性能的影响.结果表明,少量掺杂Ir4+的Co2Z型铁氧体仍具有单相的Z型平面六角结构,其磁导率实部μ′明显提高.随着烧结温度的提高,材料的磁导率实部μ′增大,但截止频率下降.在1275℃烧结的掺杂Ir4+铁氧体样品,其μ′达到16.5,截止频率仍＞1GHz,具有较好的高频性能.     

低温烧结Cu、Zn掺杂Co2-Y平面六角铁氧体及其频率特性

报道了通过BiO3的掺杂而获得的较低温度（870℃左右）下烧成的Y型平面六角结构软磁铁氧体的烧结工艺,结构特征及其磁导率和介电常数的频率特性,研究发现Cu,Zn掺杂的Co2Y型软磁铁氧体材料（Ba2Co1.2-xZnxCu0.8Fe12O22)在甚高频段具有良好的磁性能和介电性能,且此种材料烧结温度低,易于实现低温烧结,是一种可以用于甚高频段的理想的软磁材料。     

凝胶自然法制备低温烧结Z型铁氧体材料

采用干凝胶自然工艺制得铁氧体纳米粉，研究了干凝胶的自然燃烧过程，利用ＸＲＤ分析了纳米粉的晶体结构与晶粒尺寸，结合ＴＧ－ＤＴＡ数据，设计了粉体处理与陶瓷样品的烧结工艺。选用自然粉制得的低温烧结Ｚ型铁氧体材料性能为：μ１≈４（３００ＭＨｚ）；Ｑ≥１５０；ｆｔ≥１．５ＧＨｚ。     

LTCC用低温烧结Mg-Cu-Zn铁氧体的研究

采用普通陶瓷工艺合成一系列低温烧结的Mg-Cu-Zn铁氧体(Mg0.5-xCuxZn0.5O)(Fe2O3)0.95(x=0.1、0.15、0.20、0.25、0.30),在900～1100℃研究了CuO加入量对磁性能和烧结特性的影响,在此基础上进一步研究了Bi2O3以及BaTiO3掺杂对900℃烧结Mg-Cu-Zn铁氧体的成相、致密化过程、显微结构和磁电性能的影响,结果显示,低温烧结的复合Mg-Cu-Zn铁氧体有望用作LTCC材料.     

Bi掺杂对Ni-Zn-Cu铁氧体的烧结与磁性能的影响

低温烧结软磁铁氧体是表面组装元件（ＳＭＤ）中的一类关键材料。本文对Ｂｉ掺杂的低温烧结Ｎｉ－Ｚｎ－Ｃｕ铁氧体从烧结性质、结构与相组成、显微形貌、磁结构和磁性质（磁导率、品质因数及频谱）方面进行了研究，在此基础上分析了Ｂｉ掺杂对材料形成过程和磁化机制的影响，发现Ｂｉ对材料磁性能的改进所起的作用主要产生于它对材料显微结构（晶粒、晶界和气孔）的调制。     

助熔剂BBSZ对M型钡铁氧体的低温共烧改性研究

研究了助熔剂BBSZ对M型钡铁氧体的低温共烧改性。结果表明,添加适量的BBSZ助烧剂可以使钡铁氧体材料在900℃完成烧结,所得样品具有较好的致密化结构。当BBSZ的掺入量为2%时(质量分数),材料的磁特性较好,完全实现了M型钡铁氧体的低温烧结,磁性参数值有一定改善。     

产业信息快递

由清华大学新型陶瓷与精细工艺国家重点实验室承担的国家863″九五″重大项目课题—″新一代高性能低温烧结片式电感器材料″通过教育部组织的专家鉴定。此次鉴定的两项具有自主知识产权的研究成果—″低温烧结高磁导率Ni-Zn-Cu铁氧体″和″低温烧结甚高频平面六角软磁铁氧体″均已达到国际领     

凝胶自燃法制备低温烧结Z型铁氧体材料

采用干凝胶自燃工艺制得铁氧体纳米粉，研究了干凝胶的自燃烧过程，利用xRD分析了纳米粉的晶体结构与晶粒尺寸，结合TG-DTA数据，设计了粉体处理与陶瓷样品的烧结工艺。选用自燃粉制得的低温烧结Z型铁氧体材料性能为μi≈4(300MHz)；Q≥150；fr≥1.5GHz。     

掺杂Gd的Co_2Z型铁氧体的微结构和高频性能(英文)

采用普通陶瓷工艺制备了Gd掺杂的Co2Z型平面六角铁氧体3(Ba0.5Sr0.5O).2CoO.0.05Gd2O3.10.8Fe2O3,对其微结构和高频性能进行了研究。结果表明,少量掺杂Gd的Co2Z型铁氧体仍具有单相的Z型平面六角结构,其磁导率实部μ′明显提高,可达到13,而截止频率仍大于1GHz,具有较好的高频性能。随着烧结温度的提高,材料的磁导率实部μ′增大,但截止频率下降。少量Gd的掺杂对Co2Z型铁氧体的复介电常数值没有明显影响,但材料的铁电共振峰向高频区移动。     

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.……     

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.     

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.     

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 ...