氧化钇含量对Al2O3／Y—TZP复相陶瓷的影响

本文以ＺｒＯＣｌ２．８Ｈ２Ｏ、Ａｌ２Ｏ３及Ｙ（ＮＯ３）３为原料，用共沉淀法合成Ｙ２Ｏ３含量不同的ＺｒＯ２－Ａｌ２Ｏ３复合粉体，并采用热压工艺制备复相陶瓷。研究了氧化钇含量对复相陶瓷力学性能及应力诱导下氧化锆相变能力的影响。     

氧化铝基陶瓷凝胶注模成型工艺的研究——(I)悬浮体的制备及流变特性

本文研究了单相α－Ａｌ２Ｏ３及ＺｒＯ２（３Ｙ）－Ａｌ２Ｏ３复相陶瓷的凝胶注模成型工艺,着重研究了低粘度高固相体积分数浓悬浮体的制备及其固化。在碱性条件下,用自制的分散剂ＭＮ制备出固相含量高达６５ｖｏｌ％、粘度为２６７ｍＰａ．ｓ的α－Ａｌ２Ｏ３浓悬浮体,以及低粘度下固相含量达５５ｖｏｌ％的１０ｖｏｌ％ＺｒＯ２（３Ｙ）－Ａｌ２Ｏ３复相陶瓷浓悬浮体。并研究了凝胶注模奄型坯体的性能。     

氧化铝基陶瓷凝胶注模成型工艺的研究——(I)悬浮体的制备及流变特性

本文研究了单相α Ａｌ２ Ｏ３ 及 Ｚｒ Ｏ２ （３ Ｙ）  Ａｌ２ Ｏ３ 复相陶瓷的凝胶注模成型工艺, 着重研究了低粘度高固相体积分数浓悬浮体的制备及其固化在碱性条件下, 用自制的分散剂 Ｍ Ｎ 制备出固相含量高达６５ｖｏｌ％ 、粘度为２６７ｍ Ｐａ·ｓ 的α Ａｌ２ Ｏ３ 浓悬浮体, 以及低粘度下固相含量达５５ ｖｏｌ％ 的１０ ｖｏｌ％ Ｚｒ Ｏ２ （３ Ｙ）  Ａｌ２ Ｏ３ 复相陶瓷浓悬浮体并研究了凝胶注模成型坯体的性能     

SiC晶须增韧Al_2O_3及ZrO_2（Y_2O_3）基陶瓷复合材料的抗热震行

采用三点弯曲及扫描电镜等方法研究了ＳｉＣｗ／Ａｌ２Ｏ３、ＳｉＣｗ／ＺｒＯ３（Ｙ２Ｏ３）及ＳｉＣｗ／Ａｌ２Ｏ３＋ＺｒＯ２（Ｙ２Ｏ３）陶瓷复合材料的抗热震性．结果表现ＳｉＣｗ的加入使Ａｌ２Ｏ３、ＺｒＯ２（Ｙ２Ｏ３）以及Ａｌ２Ｏ３＋ＺｒＯ２（Ｙ２Ｏ３）基体的抗热震性显著提高，Ａｌ２Ｏ３陶瓷基复合材料的抗热震性明显优于ＺｒＯ２（Ｙ２Ｏ３）陶瓷基复复合材料．同时发现在Ａｌ２Ｏ３十ＳｉＣｗ材料基础上再加入少量ＺｒＯ２（２Ｙ）颗粒（１０Ｖｏ１％），也可进一步提高Ａｌ２Ｏ３＋ＳｉＣｗ材料的抗热震性．     

TiC／（Al_2O_3／Y－TZP）复相陶瓷的制备与性能

本文采用热压工艺制备ＴｉＣ和Ａｌ_２Ｏ_３共同补强Ｙ－ＴＺＰ基复相陶瓷，研究了复相陶瓷的相组成、力学性能及显微结构．发现复相陶瓷的高温强度得到显著提高，１０００℃时，组成为３０ｖｏｌ％ＴｉＣ－（２５ｖｏｌ％Ａｌ２Ｏ３／１．８Ｙ－ＴＺＰ）复相陶瓷抗弯强度高达６１４ＭＰａ．ＴｉＣ颗粒补强机制在高温下发挥了重要作用．     

TiC／（Al2O3／Y—TZP）复相陶瓷的制备与性能

本文采用热压工艺制备ＴｉＣ和Ａｌ２Ｏ３共同补强Ｙ－ＴＺＰ基复相陶瓷，研究了复相陶瓷的相组成。力学性能及显微结构，发现复相陶瓷的高温强度得到显著提高，１０００℃时，组成为３０ｖｏｌ％ＴｉＣ－（２５ｖｏｌ％，Ａｌ２Ｏ３／１．８Ｙ－ＴＺＰ）复相陶冷饮 抗弯强度高达６１４ＭＰａ，ＴｉＣ颗粒补强机制在高温下发挥了重要作用。     

2Y2O3—xCeO2对ZTM复相陶瓷相组成,显微结构,力学性能的影响

采用原位反应烧结工艺制备了ＺｒＯ２增韧莫来石（ＺＴＭ）复相陶瓷。研究和分析了在Ｙ２Ｏ３为２ｆｍｏｌ％的情况下，ＣｅＯ２添加量（用２Ｙ２Ｏ３－ｘＣｅＯ２）对ＺＴＭ复相陶瓷相组成，显微结构及力学性能的影响，结果表明，当ＣｅＯ２添加量（用２Ｙ２Ｏ３－ｘＣｅＯ２）对ＺＴＭ复相陶瓷相组成、显微结构及力学性能的影响。结果表明，当ＣｅＯ２添加量在１．５～４．５ｍｏｌ％时，ＺｒＯ２晶格畸变，晶胞长大，缺陷增加，Ｃ     

常压烧结ZTM／Al2O3复合陶瓷的力学性能

采用干法成型、常压烧结工艺制得致密的ＺＴＭ／Ａｌ２Ｏ３复合陶瓷材料。通过引入大颗粒的氧化铝，使ＺＴＭ陶瓷（氧化锆增韧莫来石陶瓷）的力学性能有明显提高。组成２０Ｖｏｌ．％Ａｌ２Ｏ３－２０Ｖｏｌ．％ＺｒＯ２－ｍｕｌｌｉｔｅ陶瓷材料，其断裂韧性为６．０６ＭＰａ·ｍ＾１／２，抗弯强度为４０３ＭＰａ。实验结果表明：Ａｌ２Ｏ３的弥散强化和ＺｒＯ２的相变增韧及微裂纹增韧是ＺＴＭ／Ａｌ２Ｏ３陶瓷的主要增韧机理。     

SiC晶须增韧Al2O3及ZrO2（Y2O3）基陶瓷复合材料的抗热震行为

采用三点弯曲及扫描电镜等方法研究了ＳｉＣｗ／Ａｌ２Ｏ３，ＳｉＣｗ／ＺｒＯ２）及ＳｉＣｗ／Ａｌ２Ｏ３＋ＺｒＯ２（Ｙ２Ｏ３）陶瓷复合材料的抗热震性。结果表明ＳｉＣｗ的加入使Ａｌ２Ｏ３，ＺｒＯ２（Ｙ２Ｏ３）以及Ａｌ２Ｏ３＋ＺｒＯ２（Ｙ２Ｏ３）基体的抗热震性显著提高，Ａｌ２Ｏ３陶瓷基复合材料的抗热震性明显优于ＺｒＯ２（Ｙ２Ｏ３）陶瓷基复合材料。同时发现在Ａｌ２Ｏ３＋ＳｉＣｗ材料基础上再加入少量ＺｒＯ２９２     

高温等静压烧结Al2O3-ZrO2纳米陶瓷

本工作用化学共沉淀法制备了平均晶粒尺寸约２０ｍｍ的２０ｍｏｌ％Ａｌ２Ｏ３－ＺｒＯ２复合粉体,不含有Ｙ２Ｏ３作为四方氧化锆的稳定剂,粉体的煅烧温度为７５０℃,ＸＲＤ结果表明,粉体中含１００％立方氧化锆相,未发现有Ａｌ２Ｏ３结晶相存在。该粉体用高温等静压方法,在１０００℃和２００ＭＰａ的条件下烧结１ｈ,得到了平均尺寸为５０ｎｍ的致密陶瓷,样品密度为密度的９８％左右。     

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.……     

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...     

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.……     

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 ...