新型抗烧蚀酚醛树脂的研究

采用不同的甲醛（F）/苯酚（P）比和复合碱性催化合成了邻对位羟甲基比例（o/p）不同的酚醛树脂。利用该酚醛树脂中邻对位交联程度变化可以优化炭化过程中苯醌式结构中间体稠环化历程。从而通过适当调整酚醛树脂受烧蚀而发生炭化时的交联密度，使炭化过程稳定，易于石墨化、提高了抗烧蚀性能。F/P比在1.6～1.8时，纯酚醛树脂的炭化率玻璃纤维/酚醛树脂复合材料的质量烧蚀率变化较小，烧蚀形貌显著改善，是比较理想的配料比。     

炭布铺层2D炭/炭复合材料研究

采用预浸炭布铺层制作炭／酚醛树脂基层合板,后经炭化、致密制备了二维炭／炭复合材料（２Ｄ－Ｃ／Ｃ）,检测了其工艺过程中的尺寸变化,测试了力学、导热、热膨胀、高等离子烧蚀性能。结果表明,２Ｄ－Ｃ／Ｃ在工艺过程中Ｚ向有明显的收缩现象,炭化收缩率达６．９９％,石墨化收缩率达５．５５％。２Ｄ－Ｃ／Ｃ的层间剪切强度（ＩＬＳＳ）大于１２．６ＭＰａ,拉伸强度大于１３３．７ＭＰａ,位伸模量大于５８．６ＧＰａ,压缩强     

超临界水和水蒸气活化制备酚醛树脂基活性炭的对比研究

采用一种新型的活化技术——超临界水活化(650℃，32Pa)和传统的水蒸气活化(800℃)来制备活性炭。用氮气吸附法表征活性炭样品的孔结构，在差热／热重分析仪上考察了原料的热失重行为，对比研究了超临界水和水蒸气活化对酚醛树脂基活性炭孔结构的影响，并探讨了酚醛树脂基炭的炭化程度对活性炭孔结构的影响。研究结果表明：(1)超临界水活化有益于中孔的发展，而水蒸气活化有益于微孔的发展。(2)炭化程度较低的酚醛树脂基炭，在较低的活化烧蚀率时就能得到高比表面积和较高中孔率的活性炭。     

酚醛树脂结构对其热解成炭特性的影响

采用傅立叶红外光谱对固化前后的酚醛树脂进行结构表征,通过热重法对固化后酚醛树脂的热降解失重温度及其高温下的成炭率进行分析,研究酚醛树脂结构中取代基的相对含量与其热稳定性及成炭率的关系。结果表明,酚醛树脂在高温下的成炭率与其结构中取代基的含量有一定的对应关系,亚甲基含量高、羰基和醚键含量低的酚醛树脂固化物高温成炭率较高。在六种不同醛酚比(F/P)的树脂固化物中,亚甲基的含量以F/P为1.2时的固化物最大,羰基的含量则以F/P为1.2时最小。固化后的六种酚醛树脂中以PF1.2用于交联的有效取代基(亚甲基)数目最多,交联密度最高,具有最高的成炭率(73.78%)。     

酚醛树脂基泡沫炭前驱体热处理过程的研究

酚醛树脂基泡沫炭是一种高性能的高强轻质隔热材料,酚醛泡沫的炭化热处理是制备酚醛树脂基泡沫炭倒丶工艺.本文以热塑性酚醛树脂为原料,采用液相低压发泡方法制备得可进一步炭化制得高性能的泡沫炭的酚醛树脂基泡沫前驱体.通过热分析仪、元素分析仪测试和分析酚醛泡沫体在炭化热处理过程中的重量和元素含量的变化及规律,并研究泡沫体在热处理过程中的径向和轴向尺寸、重量、体积和表观体积密度的变化和规律.结果表明:350～700℃,酚醛树脂泡沫体热失重较剧烈,热解速度最快,失重率约为40%,相应的热解温度会比纯树脂延缓和滞后;在热处理过程中,泡沫体在径向和轴向的收缩是不同步的:随热处理温度的提高,泡沫体的重量和体积不断减小,密度却呈现波折形变化:炭化产物中碳元素的含量随温度的升高而不断增加,各元素含量变化最明显的温度区是350～600℃.     

化学气相沉积ZrC陶瓷涂层的微观结构和抗烧蚀性能

为了提高碳／碳（C／C）复合材料的抗烧蚀性能,在C／C基体上成功制备了碳化锆（ZrC）高温抗烧蚀涂层。用常压化学气相沉积法,前驱体选用ZrCl4＋C3H6＋H2＋Ar体系。通过调节C3H6的流量,制得3种碳锆原子比的ZrC陶瓷涂层（ZrC1.0＋C,ZrC1.0,ZrC0.7）。分析了不同锆碳比ZrC涂层的相组成和形貌差异,研究了锆碳比对ZrC陶瓷涂层的烧蚀性能的影响。结果表明,3种ZrC涂层都可有效提高C／C复合材料的抗烧蚀性能,但由于微观结构特征不同,3种涂层显示不同的烧蚀性能和烧蚀机制。其中,ZrC0.7涂层试样烧蚀后,表面形成致密的氧化物层,烧蚀性能最佳,烧蚀240s后质量烧蚀率和线烧蚀率分别为1．1×10^-4g／cm^2·s和0．3×10^-3mm／s。     

酚醛纤维在热处理过程中微结构的变化

采用热塑性酚醛树脂经熔融纺丝和酸催化固化获得酚醛纤维。借助比表面积及孔结构测定仪、IR、TG-MS和XRD等揭示了酚醛纤维在炭化过程中微结构的发展：研究结果表明：在450℃～900℃的热处理过程中，850℃时BET比表面积达到最大值1040m^2／g；同时，伴随大量分解气的逸出，炭基体内部形成孔道。     

XRD研究芳基乙炔聚合物炭化过程中的结构变化

根据热失重曲线，元素分析和X射线衍射分析了芳基乙炔聚合物炭化过程中的结构变化，结果表明，芳基乙炔聚合物在900℃炭化时，成碳率高达84％,随着炭化温度的升高，碳含量增加，H／C比减小，在600℃以前，随着炭化温度的升高，聚合物原有的序态结构逐渐被破坏；600℃以后，随着炭化温度的升高，新的序态结构逐渐形成。     

有机硅改性酚醛树脂热稳定性的研究

用热失重法研究了有机硅改性酚醛树脂的热稳定性和烧蚀成碳率。结果表明,各种因素的影响程度依次为甲醛补加量,苯酚／甲醛比值及有机硅用量。用动态力学性能分析仪考察了树脂的固化条件。改进后的酚醛树脂在氮气中８２０℃的烧蚀成碳率可超过７０％。     

水蒸汽活化树脂炭用做双电层电容器电极材料

以热固性酚醛树脂为前驱体，采用水蒸汽为活化剂，通过改变活化时间，制备出了一系列双电层电容器用活性炭（PFR（1—5））．采用低温氮气吸附法测定BET比表面积和孔结构，发现随着活化时间的增加，活性炭的比表面积和中孔率增大．电化学测试表明，用活化时间为5h的PFR5H制备的模拟EDLC的比电容，在有机体系中50mA／g恒流放电比电容达106．5F／g，1000mA／g下放电仍保持99．7F／g，仅衰减了6．4％，具有良好的倍率特性．交流阻抗谱测试结果显示PFR5H的内阻最低，具有良好的电容性能和功率特性．     

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 ...