SHS离心复合钢管陶瓷内衬的组织结构

采用自蔓延高温合成技术离心法制备Al2 O3陶瓷内衬复合钢管。利用扫描电镜及X射线衍射方法对陶瓷内衬的显微组织及物相构成进行了分析。结果表明 ,陶瓷内衬复合钢管由钢管层、金属铁和陶瓷组成的过渡层以及陶瓷层共三层构成 ,其中钢管与铁过渡层之间为机械结合 ,铁过渡层与陶瓷层之间形成冶金结合。陶瓷层组织由垂直管壁生长的α Al2 O3柱状晶和沿其晶间分布的FeO·Al2 O3铁铝尖晶石相以及少量FeO·Al2 O3·SiO2 玻璃相构成 ,玻璃相分布于铁铝尖晶石的晶界并将其包围起来 ,这种结构有利于减轻铁铝尖晶石对复合管内衬抗腐蚀性的不良影响。     

添加剂对煤粉喷枪SHS陶瓷内衬组织和性能的影响

采用重力分离SHS法制备了陶瓷内衬煤粉喷枪枪管，试验得出，陶瓷层主要由构成枝晶的αAl2O3基体相和分布于其间的FeO·Al2O3尖晶相所组成，SiO2主要以石英相结构存在于枝晶晶界上；在反应物料中加入适量的SiO2和Cr2O3均可有效地提高内衬陶瓷层的相对密度；SiO2将使陶瓷层的硬度和复合钢管的抗压剪强度降低，Cr2O3却使二者均有所回升；在内衬陶瓷层中分布着径向裂纹和网状裂纹，加入SiO2将减少裂纹密度，Cr2O3却使裂纹密度增加。     

重力分离SHS双衬陶瓷复合管的显微组织与耐蚀性

通过重力分离SHS技术制备双衬陶瓷复合管 ,发现第二衬陶瓷层的尖晶石含量和组织形貌发生改变 ,双衬陶瓷层间存在着Al2 O3 基体和 (Al2 O3 +FeO·Al2 O3 )共晶组织的重熔区 ,引起两者的裂纹密度下降 .复合管的耐蚀性测试结果表明 ,双衬陶瓷复合管的腐蚀失重率分别低于1Cr1 8Ni9Ti不锈钢管和单衬陶瓷复合管 3个和 2个数量级 .     

CuO对重力分离SHS陶瓷内衬复合管组织的影响

采用重力分离自蔓延高温合成法(Self-propagating High-temperature Synthesis,简称SHS)法,以(Al-Fe2O3-CuO) SiO2复合铝热体系为铝热剂,制备了陶瓷内衬复合管.分析了添加剂CuO对陶瓷层组织的影响.XRD分析表明.陶瓷层主晶相为α-Al2O3、FeAl2O4、Al2SiO5,复合管的中间金属层由α相(Cu在α-Fe中的固溶体)和Cu相组成.CuO作为助燃剂,可提高燃烧速度和燃烧温度并减少陶瓷中FeAl2O4的含量.     

机械振动对SHS陶瓷内衬复合管显微结构和力学性能的影响

通过在重力分离SHS法制备陶瓷内衬复合管过程中施以不同振幅与振频的单自由度上下往复式机械振动 ,研究了机械振动对SHS铝热燃烧、陶瓷凝固及复合管组织性能的影响 .研究发现 ,机械振动并相应提高振频可以提高燃烧温度、燃烧速率和反应转化率 ,促进Al2 O3 Fe液相重力分离和陶瓷致密过程 ,并使陶瓷层的凝固组织发生改变 ;性能测试结果表明机械振动并相应提高振频可以提高复合管的各项力学性能指标和内衬陶瓷层的表面质量 .     

重力分离SHS内衬陶瓷涂层合成机理及添加剂行为

在采用SHS铝热 -重力分离技术制备陶瓷内衬复合管的基础上 ,研究了陶瓷涂层的合成机理及相应添加剂在合成过程中的行为 .研究得出 ,重力分离SHS合成过程经历燃烧合成、液相分离和陶瓷凝固三个基本过程 ,陶瓷层致密化贯穿于三个过程之中 ;SiO2 、CrO3 及NaF添加剂通过对三个过程的影响进而影响内衬陶瓷涂层与复合管的各项性能 .研究表明 ,在铝热剂为Al+Fe2 O3 +2 %SiO2 + 6%CrO3 + 1 %NaF条件下 ,内衬陶瓷涂层及复合管具有良好的综合性能 .     

SHS陶瓷内衬复合管合成及陶瓷致密化技术

本文通过比较离心SHS技术和重力分离SHS技术的合成工艺，从理论上阐述合成SHS陶瓷内衬复合管所涉及的燃烧合成、液相分离和陶瓷凝固三个重要过程，并着重探讨了SHS陶瓷内衬复合管技术研究领域中陶瓷致密化问题，提出了提高SHS陶瓷内衬复合管质量的有效途径。     

SHS陶瓷内衬复合管合成及陶瓷致密化技术

本文通过比较离心SHS技术和重力分离SHS技术的合成工艺 ,从理论上阐述合成SHS陶瓷内衬复合管所涉及的燃烧合成、液相分离和陶瓷凝固三个重要过程 ,并着重探讨了SHS陶瓷内衬复合管技术研究领域中陶瓷致密化问题 ,提出了提高SHS陶瓷内衬复合管质量的有效途径     

SHS陶瓷内衬复合管接合界面结构及力学性能研究

基于重力分离自蔓延过程,Al-Fe2O3-CrO3-TiO2-C燃烧体系,制备出了一种新型的FeO-TiC-Al2O3-CrO陶瓷内衬钢管,其内衬陶瓷层厚度均匀、致密、表面光滑.研究表明,加入TiO2、Na2B4O7和石墨后,在陶瓷/金属结合界面形成了Ti、Fe元素的梯度分布,B离子在Al2O3熔体表面的富集,改善了界面结合处Al2O3陶瓷熔体与铁合金过渡层之间的浸润性;双层梯度结构提高了陶瓷/金属界面结合强度,使复合管具有良好的力学性能.     

氧化铁粉末化学组成对合成SHS复合弯管内衬陶瓷的影响

基于重力分离SHS法制备陶瓷内衬复合弯管 ,研究了氧化铁粉末化学组成对SHS复合弯管内衬陶瓷的影响 .研究发现在铝热剂相同质量分数条件下 ,存在于工业原料Fe2 O3 粉末的杂质比SiO2 添加剂对燃烧过程的稀释效应更为强烈 .在工业原料Fe2 O3 +Al体系中加入适量的Fe3 O4+Al体系 ,使燃烧温度、蔓延速率及SHS反应转化率均有所升高 ;但加入过量的Fe3 O4+Al体系 ,虽然使蔓延速率进一步增大 ,但却引起燃烧温度和SHS反应转化率有所下降 .实验表明 ,在工业原料Fe2 O3 +Al体系中加入 1 5 %的Fe3 O4+Al体系 ,使复合弯管内衬陶瓷性能达到并超过用分析纯Fe2 O3+Al体系所制备的复合弯管内衬陶瓷性能 .     

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.