YAG悬浮体分散特性和流变性能的研究

采用大分子量的聚丙烯酸做分数剂和粘接剂,通过对YAG粉体在去离子水介质中的Zeta电位和浓悬浮体的黏度等测试,详细研究了YAG悬浮体的分散特性以及流变行为.结果表明,悬浮体pH值和聚丙烯酸浓度将严重影响YAG粉体颗粒表面的Zeta电位,YAG粉体颗粒在pH=ll.5,聚丙烯酸浓度为2％(质量分数,下同)时Zeta电位绝对值最大.悬浮体的黏度随固相含量的增加而增热,当固相含量小于60％时YAG悬浮体的黏度基本上不随剪切速率的变化而变化,为近牛顿流体,当固相含量大于60％时YAG悬浮体的黏度隧剪切速率的增加而减小,为剪切銮稀型流体.用pH=11.5,聚丙烯酸浓度为2％,固相含量为60％的YAG浆料注浆可以得到均匀性好,有机物成分单一且含量低的生坯.     

α-Al2O3/ZrO2(3Y)复相陶瓷悬浮体的流变性能

研究了分散剂添加量、固相体积分数、研磨时间及复合粉体组成对á-Al2O3/ZrO2(3Y)复相陶瓷悬浮体流变性能的影响.结果表明:当pH值在9.0左右,分散剂添加量为1.20wt%时,á-Al2O3/ZrO2(3Y)(30wt%ZrO2)悬浮体的粘度和剪切应力值较低,悬浮体的粘度和剪切应力值随固相体积分数和ZrO2含量增加而增加,当ZrO2含量较高时,适当调整分散剂添加量,仍可制备流变性较好的悬浮体.在本实验条件下,研磨4h的悬浮体的流变性最佳.     

聚乙烯醇缩丁醛/聚乙二醇体系的流变性能

采用美国TA公司的AR2000型应力控制流变仪研究了聚乙烯醇缩丁醛/聚乙二醇(PVB/PEG)体系的流变学性能,研究了温度、PVB质量分数与PEG分子量对PVB/PEG体系的流动曲线和非牛顿指数等流变特性的影响。结果表明PVB/PEG体系存在剪切变稀行为,为假塑性流体;温度升高,表观黏度减小,非牛顿指数增大;PVB质量分数增加,表观黏度增加,非牛顿指数减小;PEG分子量增加,表观黏度增加,非牛顿指数变化很小。在一定的浓度和剪切速率下体系的黏度随温度的变化符合Arrhenius方程式,粘流活化能随剪切速率的增加而减小。     

潜热型纳米流体粘度特性的实验研究

实验测量了潜热型纳米流体TiO2-BaCl2-H2O的粘度,分析了纳米粒子体积分数和温度对纳米流体粘度的影响.实验结果表明,在BaCl2水溶液中添加纳米TiO2会增加其粘度,且随着粒子浓度的增加,粘度增加越显著;粘度随温度降低而升高.潜热型纳米流体TiO2-BaCl2-H2O的粘度不随剪切应力的变化而变化,表现为牛顿型流体的流变特性.基于实验数据,建立了潜热型纳米流体TiO2-BaCl2-H2O粘度的计算模型,模型预测值与实验值的误差在2％以内.     

氮化铝陶瓷浆料流变性能的研究

系统地研究了流延法制备氮化铝基片过程中影响流延浆料粘度的主要因素.分析了研磨时间、有机混合溶剂掺量、分散剂掺量及粘结剂、塑性剂对氮化铝浆料流变性能的影响,并对实验条件下测得的流变曲线采用Hershel Bulkley模型进行拟合,拟合出的Hershel Bulkley屈服应力τc较好地反映了浆料的稳定性,研究结果表明:分散剂掺量为2.5%(体积分数)时,浆料的τc较低;浆料的τc随固相体积分数的增加而增加;研磨时间为4h制备的浆料τc最低,流动性能最好;浆料的粘度随着塑性剂与粘结剂的比值R的增加而急剧减小,流变性能得到明显改善.     

低浓度Al2O3-水纳米悬浮液粘度的研究

分别对粒径为40nm和65nm的Al2O3-水纳米悬浮液的粘度在不同浓度、温度下进行了实验研究.结果表明,Al2O3-水纳米悬浮液的粘度随浓度的增加而增加,随温度的升高而降低;在相同体积分数下,随颗粒尺寸的减小而增加.当Al2O3纳米颗粒体积分数为0.1%时,粒径为40nm和65nm的Al2O3-水纳米悬浮液的粘度比水分别提高了11.03%和0.83%;当Al2O3纳米颗粒体积分数为0.5%时,粘度比水分别提高了28.28%和17.50%.与粘度理论值比较发现,测量值远大于理论值,且测量值与体积分数呈非线性关系,而理论值与体积分数呈线性关系.     

氧化铝黑瓷浆料流变性能的研究

通过对氧化铝黑瓷粉料进行预烧技术处理,增大颗粒尺寸、降低粉体比表面能、改善其团聚现象,制备出固相体积分数达55%的氧化铝黑瓷稳定料浆,并研究了分散剂用量、体系固相体积分数、R值(塑性剂/粘结剂)对料浆流变性的影响.结果表明:浆料的粘度随剪切速率增加而下降,呈剪切稀化的流变学特性,随着固相体积分数的增加,浆料的最佳分散剂用量也相应增加;浆料的粘度随着R值的增加而急剧降低,流变性能得到明显改善.     

不同粒径SiO_2粒子对磁流变液性能的影响

分别以不同粒径的SiO2粒子作为触变剂,以羰基铁粉为磁性颗粒,制备了矿物油基磁流变液。通过测量零场粘度、流变曲线、沉降率,以及摩擦系数等,考察了SiO2的粒径对磁流变液流变特性、稳定性以及摩擦学性能的影响。实验结果表明,(1)中等粒径的SiO2作为触变剂会明显增加磁流变液的零场粘度;(2)小粒径SiO2粒子的填补空隙作用,使得磁流变液在强磁场下磁致剪切应力明显增强;(3)磁流变液的沉降稳定性随着粒径的增大而明显改善,再分散性能下降;(4)较大粒径(100 nm)的SiO2粒子的磁流变液表现出良好的减摩性能。     

ZTA陶瓷注凝成型浆料流变性能的研究

研究了ZTA陶瓷注凝成型浆料流变性能的影响因素.结果表明:单体(AM)在液相中质量百分浓度为10%、交联剂与单体的比(MBAM/AM)较低时,悬浮体粘度较低;浓悬浮体粘度和剪切应力随分散剂掺量增加而减小,拟合的流变模型倾向为Herchel Bulk;ZrO2原料的粒度对浆料流变性有重要影响,较粗ZrO2原料对浆料流变性影响不大,占少量的超细ZrO2决定了ZTA浓悬浮体的性质;试验条件下研磨时间以9h为最佳.     

底液对石灰水法制备氢氧化镁沉降性能的影响

以氯化镁为镁源,石灰水为沉淀剂,分别采用正向、反向、双向和双向底液4种滴定方式制备氢氧化镁,其中双向底液合成方式最佳.研究了氯化钙底液浓度、体积对氢氧化镁沉降性能的影响.研究表明,氯化钙溶液质量分数为15 ％、溶液体积为50mL时,氢氧化镁沉降性能最佳.研究了不同反应体系活度积对氢氧化镁沉降性能的影响,结果表明,氯化钙溶液质量分数和体积的增加都有利于反应体系过饱和度的降低.     

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.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from