固体材料低温热导率测试系统

研制出工程材料低温热导率测试系统.测试采用稳态纵向热流法,高真空绝热恒温器,并利用热开关装置,解决了传统测试方法降温速率慢的问题.通过与标准样品比对,证明测试误差在5%以内.利用该测试系统研究了不锈钢、钛合金及镁合金的低温热导率.     

绝热材料低温热导率测试装置

针对被测试样聚氨脂塑料硬泡沫的低温性能,采用平板热导仪[1],用稳态法测量其低温热导率.以液氮和液氦作为冷源,用真空绝热、控制冷热板温度,可以获得不同温度下的微分热导率和平均热导率.     

碳纤维复合材料低温热导率分析计算模型

探讨了碳纤维复合材料（ＣＦＲＰ）低温传热机理及低温热导率的一般规律和影响因素；在分析讨论的基础上，建立了ＣＦＲＰ低温热导率的计算模型，并将计算结果与测试结果进行了比对。为设计、推算ＣＦＲＰ材料的低温热导率提供了一种简便、较准确的手段。     

非金属绝热材料低温热导率测试装置

建立了一套非金属绝热材料低温热导率测试装置,测试采用稳态轴向热流法,高真空绝热,通过可控气体热开关提高了样品的降温速度,运用该装置对聚氨酯隔热材料液氮到室温温区热导率进行了测量,并对装置的重复性以及漏热和误差进行了分析。     

碳纤维复合材料低温热导率测试方法

针对碳纤维复合材料在X、Y、Z 3个方向的各向异性特点,分析其传热机理,讨论分析了碳纤维复合材料低温热导率测试方法.采用两种不同方法分别测试出碳纤维复合材料3个方向的低温热导率数据.根据测试结果,讨论了影响测试精度的主要因素,如温度、试样装配、试样厚度的影响等,给出了部分碳纤维复合材料低温热导率与温度关系曲线.     

制冷机做冷源的低温热导率测量装置研制

设计研制了1套以4.2 K制冷机为冷源的低温热导率快速测量装置.该装置采用可拆卸的具有独立真空环境的样品测试杆,使得样品测试部件与低温冷源部件分离,从而实现不破坏制冷机冷源真空环境及制冷机不复温的情况下快速更换样品.高真空绝热恒温样品杆通过高导热柔性热桥与制冷机冷头良好热耦合.热导率测试采用稳态绝热纵向热流法.除快速测...     

多层绝热的间隔材料有效低温热导率测试研究

叙述了多层绝热的间隔材料玻璃纤维布、隔热纸的有效低温热导率测试方法,为薄层材料的有效低温热导率测试提供了一种方法,并对测试结果和影响因素,如叠层密度和层密度等进行了讨论分析。     

网状碳纤维面板蜂窝夹层结构低温热导率测试研究

对网状碳纤维面板蜂窝夹层结构T,L,W三个方向的低温热导率进行了测试研究,得到了网状碳纤维面板蜂窝夹层结构低温热导率的性能与温度变化曲线,在试验的基础上,讨论分析了网状碳纤维面板蜂窝夹层结构低温热导率的影响机理,通过试验和比对,从中找 具有普遍性的规律,建立了一般蜂窝夹层结构低温热导率的变化规律模型,为推算蜂窝夹层结构低温热导率数据提供了参考依据。     

低温绝热管道漏热量在线测试的研究

低温绝热管道漏热量测量的热流计法就是采用热流计直接测试低温绝热管道表面的热流进而计算出管道漏热量的测量方法。采用热流计法可以实现管道漏热量的免工质更换、免拆装的在线测试,同时测试精度也可保证。另外,还建立了低温绝热管道在线漏热量测试结果的合于使用评价方法,其中对评价中的重要参数—管道夹层当量热导率进行了详细分析。     

丙烯酸酯压敏胶低温热导率测试研究

介绍了丙烯酸压敏胶低温热导率的测试原理及测试方法,给出了测量结果和热导率～温度曲线。并对测试数据和影响因素进行了讨论。     

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.