不同粉磨方式矿渣粉对矿渣水泥流变性的影响

用激光粒度分析仪（LPS）研究了球磨和立磨粉磨的矿渣粉的粒度分布，用旋转粘度计对矿渣水泥的流变性能进行了测量。发现：球磨机所加工的矿渣粉比立磨加工的矿粉颗粒尺寸分布宽、细颗粒含量高；矿渣粉比表面积相近时，矿渣掺量在小于30%和大于40%时由球磨矿渣粉制成的矿渣水泥比立磨矿渣水泥的屈服应力和粘度小，而掺量在30%～40%之间时球磨矿渣水泥的粘度和屈服应力较立磨的稍大。此外，对矿渣粉颗粒群与水泥流变性之间进行了灰色关联分析，发现小于10μm的矿渣颗粒增加了水泥浆的屈服应力和粘度，而大于10μm矿渣颗粒却削弱了水泥浆的屈服应力和粘度。     

粉煤灰、石灰石粉复掺对水泥净浆工作性能的影响

通过检测水泥净浆流动度和Marsh时间,研究了不同掺量粉煤灰与石灰石粉对水泥浆体的工作性能的影响。结果表明,粉煤灰单掺掺量为20%的水泥浆体工作性能最优,单掺石灰石粉的水泥浆体随着掺量增加流动度呈线性增长;复掺掺量分别为20%、30%,粉煤灰和石灰石粉等量时,水泥浆体工作性能最好;通过对水泥、粉煤灰和石灰石粉的粒径分析,从微观角度分析了不同级配的水泥浆体的工作性能。     

TerminalBlend废胶粉-纳米SiO_2改性沥青粘温关系及低温韧性

为评价废胶粉-纳米复合改性沥青的高温抗变形性、流变特性及低温韧性,制备了湿法Terminal Blend胶粉-纳米SiO_2复合改性沥青,并借助旋转粘度、针入度、软化点、5℃和15℃延度试验进行了性能表征,还基于实测表观粘度拟合了复合改性沥青粘度-温度关系。结果表明:掺加纳米SiO_2后,复合改性沥青针入度减小,软化点升高,高温抗变形性能得到改善,且纳米SiO_2掺量越大,改善越显著;纳米SiO_2掺量4%时5℃延度比未掺前提高约37.5%。此外,复合改性沥青高温粘度较基质沥青和未纳米改性时有所增加,但135℃粘度不超过1500cP,施工和易性良好;粘度数据拟合还表明在135~200℃温度域内,复合改性沥青粘温关系符合较好的指数关系。     

改性羧甲基羟丙基纤维素醚热稳定性研究

通过研究纤维素醚水溶液在不同温度下的粘性行为和纤维素醚在静态空气和氮气流中的热裂解及其裂解活化能计算,探讨了改性羧甲基羟丙基纤维素醚的热稳定性。结果表明:与羧甲基羟丙基纤维素醚相比较,改性羧甲基羟丙基纤维素醚的粘度热稳定性和裂解热稳定性都有一定程度的提高。     

普鲁兰多糖对水泥净浆性能的影响

主要研究一种新型微生物多糖——普鲁兰多糖(Pullulan)对新拌水泥浆体性能的影响,对比分析了不同掺量的普鲁兰多糖对水泥净浆标准稠度用水量、凝结时间、流动度和Zeta电位的影响,以及对硬化水泥浆体力学性能的影响.研究表明:普鲁兰多糖增大了水泥浆体标准稠度用水量,延长了水泥的凝结时间;随着普鲁兰多糖掺量的增加,新拌水泥浆体的初始流动度降低,但随着时间的延长,流动度不降反升;普鲁兰多糖的掺入降低了水泥浆体的Zeta电位,0～13 min内,Zeta电位值极度不稳定,然后趋于平稳状态;普鲁兰多糖与减水剂(PC)复掺后,随着普鲁兰多糖掺量的增加,水泥浆Zeta电位发生了复杂的变化过程;普鲁兰多糖对硬化水泥浆体的抗压强度无明显不利影响.     

纤维素醚-膨胀珍珠岩耦合作用下水泥浆体早期水化规律

利用水化放热速率、XRD、FT-IR、DTG和Ca(OH)2含量测试手段,研究了羟丙基甲基纤维素醚和膨胀珍珠岩两种保水因子单掺和耦合作用条件下水泥浆体的早期水化规律及二者的作用机理。结果表明羟丙基甲基纤维素醚能够显著降低水泥浆体早期水化放热速率峰值,且能延缓诱导期和加速期出现的时间,对水泥浆体中后期水化没有明显的延缓效应。膨胀珍珠岩可以降低早期水化放热速率峰值,效果较羟丙基甲基纤维素醚差,但对水泥水化无延缓效应。当二者耦合作用时,具有显著的叠加效应。水化12h时,羟丙基甲基纤维素醚和膨胀珍珠岩能够显著降低水泥浆体中Ca(OH)2含量,较空白样分别降低了43.6%和9.1%。水化1和3d时,水泥浆体中Ca(OH)2含量随二者掺加而降低的趋势变缓。     

有机缓凝剂对水泥改性乳化沥青胶浆的改善效果研究

将适量的萘系减水剂(Naphthalene superplasticizer,NSP)加入到改性乳化沥青(Modified asphalt emulsified,MAE)中能够实现水泥和改性乳化沥青的直接拌和。当NSP的掺量为4%(质量分数,下同)时,水泥沥青胶浆(Cement asphalt mastic,CAM)工作性能不佳。本试验所使用的沥青和三种有机缓凝剂分别为:改性乳化沥青、海菜粉、聚丙烯酰胺(PAM)、葡萄糖酸钠。试验结果表明:海菜粉对CAM的改善效果最好。当海菜粉掺量为0.03%时,CAM 7 d内的强度增量比较大; 28 d的抗拉强度和抗压强度最高,凝结时间最短,干缩变化幅度较小。随着海菜粉掺量的增加,CAM的抗拉强度和抗压强度有所降低。PAM由于其自身有很强的粘稠度和絮凝作用,因而对CAM的粘弹性有很大影响;当PAM掺量为0.02%时,CAM的粘度最大,坍流度最小;当PAM掺量由0.01%增加到0.03%时,CAM的粘度、干缩量和抗压强度呈现先增大后减小的规律,坍流度和凝结时间呈现先减小后增大的规律,而抗拉强度随掺量的增加而增大。葡萄糖酸钠对CAM的改善效果最差,虽然加入葡萄糖酸钠能改善CAM的流动性、粘度等非力学性质,但会引起CAM试块较大幅度的体积收缩和干缩,抗拉强度和抗压强度明显降低,凝结时间过长,试件表面出现裂缝等不良现象。     

高模量温拌改性剂对沥青基本指标和疲劳性能影响研究

为评价高模量温拌改性剂对基质沥青基本指标和疲劳性能的影响,在70#基质沥青中掺入不同剂量改性剂,采用动态剪切流变仪(DSR)对试验沥青进行动态扫描试验研究。首先制备了不同掺量高模量温拌改性剂改性沥青,随后评价其基本性能,并通过布氏粘度试验分析不同沥青的拌和温度与压实温度;再采用DSR对不同掺量高模量温拌改性剂改性沥青进行线性振幅(LAS)扫描试验和时间扫描试验。通过LAS试验和粘弹性连续损伤(VECD)模型分析不同掺量(0%,2%,3%,4%)改性沥青和SBS改性沥青的疲劳特性;基于动态扫描试验,应用耗散能原理探究不同掺量改性剂对沥青疲劳性能,同时把不同掺量改性70#沥青与SBS改性沥青的试验结果进行比对,并分析了改性剂的作用机理。试验结果表明：随着高模量温拌改性剂掺量增加,软化点增加,针入度和延度减少,3%掺量改性沥青软化点稍优于SBS沥青;改性沥青粘度随着改性剂增加先减后增,改性后沥青的拌和、碾压温度与70#基质沥青相当,均远小于SBS改性沥青,即改性后的沥青有良好的温拌效果;高模量温拌改性剂可不同程度提高沥青的疲劳性能,合适掺量改性沥青疲劳性能可与SBS改性沥青相当,高模量温拌改...     

不同配比改性硫氧镁水泥胶凝试样的强度影响

改性硫氧镁水泥混凝土作为一种新型耐腐蚀材料,其具有很高的推广应用价值,对不同配比、不同外加剂含量下的改性硫氧镁水泥胶凝试样进行强度测试,结果表明:采用50%活性含量的轻烧氧化镁,柠檬酸对配比6-20和9-20的改性硫氧镁水泥试样流动度改性效果明显;配比6-20改性硫氧镁水泥试样28 d抗折、抗压强度都随着外加剂掺量增加而增加;小于2%的柠檬酸掺量对配比9-20改性硫氧镁水泥试样抗压强度改性作用巨大;掺4%的柠檬酸时,9-20配比的改性硫氧镁水泥试样具有最高的28 d抗折强度和较高的折压比;根据28 d强度分析,针对9-20配比,活性含量50%、60%的轻烧氧化镁,最佳柠檬酸掺量分别为3%～4%与1.2%。     

丁苯胶乳改性水泥混凝土的力学性能及耐久性实验分析

目前聚合物水泥混凝土已成为高性能混凝土研究的一个重要组成部分。中实验采用了一种聚合物乳液(丁苯胶乳)对高性能混凝土进行改性处理,研究不同丁苯胶乳掺加量对水泥混凝土基本力学性能、韧性、自收缩性能及抗氯离子渗透性能的影响。实验结果表明,丁苯胶乳改性水泥混凝土的抗压强度随着丁苯胶乳掺加量的增加有所降低;而丁苯胶乳的加入,对混凝土的劈裂抗拉强度、抗折强度及韧性有较大提高,且掺量为15%的增强效果最明显,劈裂抗拉强度和抗折强度的提升幅度分别达到17.4%和23.8%,;掺量为10%的情况下韧度指数最高,增加幅度达到71.1%;丁苯胶乳改性混凝土浇注24 h后的总收缩值,随着丁苯胶乳掺量的增加而逐渐减少,掺量为15%情况下的总收缩值降幅高达35%;同时,改性后水泥混凝土的抗氯离子扩散能力有所提高,抗渗性能也得到改善。     

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...     

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.     

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.     

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.     

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.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.