Sc2O3稳定的ZrO2超细粉的制备与烧结

本文用化学共沉淀法制备了Ｓｃ２Ｏ３稳定的ＺｒＯ２纳米超细粉。用ＸＲＤ，ＴＥＭ，ＳＥＭ以及ＢＥＴ测比表面等方法分析了粉体和烧结体的相组成的显微结构及其性能。实验结果表明６．０、７．８、９．６ｍｏｌ％Ｓｃ２Ｏ３掺杂量的粉体易于烧结，而３．５、１２．０ｍｏｌ％Ｓｃ２Ｏ３掺杂量的粉体则不易烧结，原因在于样品冷却过程中相变引起的体积变化以及烧结体中双重显微结构的存在。     

氮化硅复合陶瓷的制备及其显微结构分析

以Si3N4、SiC为原料,Y2O3、Al2O3、MgO为助剂,在1500℃氮气气氛下采用无压烧结的方式进行烧结。利用SEM和XRD观察分析了材料的组织结构和物相组成,研究了材料的配方、制备工艺和烧结性能之间的关系。结果表明,当SiC含量为5％时,烧结体的空隙率为22．9％,抗弯强度为395MPa,显微结构均匀、晶粒细小。     

低膨胀系数材料二铝酸钙的合成及其显微结构研究

采用轻质CaCO3(或纯铝酸钙水泥)和α-氧化铝为原料合成了二铝酸钙(CA2)材料,研究了反应原料、热处理温度和成型压力对CA2烧结性能和显微结构的影响,检测CA2的热膨胀系数,并借助XRD、TG-DSC和SEM等测试手段分析和观察了材料的合成过程及显微结构.结果表明:采用轻质CaCO3(或纯铝酸钙水泥)和活性氧化铝为原料可以合成低膨胀系数CA2材料;坯体成型压力对试样烧结性能没有显著影响;反应原料和热处理温度不同导致CA2材料的烧结性能和显微结构有较大的差异.     

TiB2/FeMo陶瓷的显微结构与力学性能

以Fe-Mo为助烧剂，通过热压制备了TiB2陶瓷．研究了烧结温度、烧结时间对材料显微结构和力学性能的影响，分析了烧结致密化过程．实验结果表明，随着热压烧结温度升高，材料抗弯强度、洛氏硬度出现峰值，热压烧结时间延长，抗弯强度有所下降．液相烧结的重排阶段致密化速率最快．     

工艺条件对MnZn功率铁氧体性能的影响

研究了粉末体粒度、成型密度和烧结工艺对ＭｎＺｎ功率铁氧体材料性能的影响，指出了组成为Ｚｎ０．１６Ｍｎ０．７６Ｆｅ２．０８Ｏ４的材料的最佳工艺条件，得到了与日本ＴＤＫ公司ＰＣ５０材料性能相的的功率铁氧体。     

热压烧结TiB2陶瓷的显微结构和力学性能研究

以Y₂O₃－Al₂O₃为烧结助剂,通过热压制备了TiB₂陶瓷,研究了烧结温度、烧结时间和晶化处理对材料的显微结构和力学性能的影响．实验结果表明,随着烧结温度的升高,烧结体失重增加,其抗弯强度和断裂韧性降低;烧结时间延长,其显微结构的均匀性降低,对力学性能不利．晶粒直径对TiB₂陶瓷的力学性能有重要影响．晶化处理能够导致晶界拆出YAG相,从而提高TiB₂陶瓷的高温抗弯强度．     

氮气压力和稀释剂对燃烧合成β-Sialon的影响

以Si、al、Al2O3和Si3N4粉末为原料，采用燃烧合成工艺，在高氮气压力下制备了单相β-Sialon（z≈0．5～2．0）粉末；并详细讨论了氮气压力和稀释剂的量对燃烧产物的相组成和显微结构的影响．     

碳化硅陶瓷及其复合材料的热等静压烧结研究

本文通过采用热等静压（ＨＩＰ）这一先进的烧结工艺，研究了Ａｌ２Ｏ３添加量对ＳｉＣ陶瓷之显微结构与力学性能的影响。并成功地制备出Ｓｉ３Ｎ４粒子以及ＳｉＣ晶须补强的ＳｉＣ基复合材料，结果表明：Ａｌ２Ｏ３是ＨＩＰ烧结ＳｉＣ陶瓷及其复合材料的有效添加剂，当添加３ｗｔ％Ａｌ２Ｏ３时，采用ＨＩＰ烧结工艺在１８５０℃温度和２００ＭＰａ压力下烧结１ｈ就可获得密度分别高达９７．３％、９９．４％和９７．０％的ＳｉＣ的     

掺杂对PMN铁电陶瓷烧结工艺和介电性能的影响

使用常用的两步法,研究了基体掺杂不同物质对ＰＭＮ陶瓷的烧结工艺和介电性能的影响．经研究发现,当掺杂 １ｍｏｌ％Ｌｉ_２Ｏ时,可以实现 ９５０～１０００℃左右的中温烧结,材料的常温介电常数和介电损耗分别为 １３５００和 ０．５５％,都优于纯 ＰＭＮ．当掺杂 ２ｍｏｌ％时,可以将烧结温度降到８００～９００℃的低温烧结范围,且介电损耗明显下降．分析结果表明;材料的显微结构良好,材料的致密化程度较高．另外,掺加 Ｌｉ_２Ｏ和 ＳｒＯ可以分别稍微减小和增加材料的弥散相变程度．同时本文还研究了ＰＭＮ陶瓷的微观结构和介电弛豫的情况．     

AlOOH对Al2O3直接凝固注模成型坯体强度等性能影响

为了改善直接注模成型（ＤＣＣ）氧化铝的坯体性能，在Ａｌ２Ｏ３－ＤＣＣ过程中加入ＡｌＯＯＨ本文详细研究了Ａｌ２Ｏ３＋ＡｌＯＯＨ体系的湿坯性能，干燥行为及烧结致密化过程，结果表明，少量ＡｌＯＯＨ加入可显著提高Ａｌ２Ｏ３的湿坯抗压强度和弹性模量，当ＡｌＯＯＨ体积含量〈３．０％时对干燥过程没有影响，干燥坯体经无压烧结后可获得烧结密度达３．９７ｇ／ｃｍ＾３（９９．７％ＴＤ）。显微结构均匀的α－Ａｌ２Ｏ３相。     

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.     

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...     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.     

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.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.