铅离子对复合磷酸盐磷酸镁水泥水化硬化特性的影响

研究了铅离子对复合磷酸盐磷酸镁水泥水化硬化特性的影响及其在复合磷酸盐磷酸镁水泥中的稳定性。实验结果表明,复合磷酸盐磷酸镁水泥抗压强度随着铅离子掺量的增加而降低,其中硝酸铅掺量达到10%时,复合磷酸盐磷酸镁水泥的各个龄期的抗压强度发生明显下降。铅离子对复合磷酸盐磷酸镁水泥凝结时间没有明显影响。在复合磷酸盐磷酸镁水泥水化过程中,铅离子对水泥体系的pH值影响不大,但能够造成水泥水化放热峰出现的时间延迟,水化放热的总量减少并影响主要水化产物的结晶程度。在复合磷酸盐磷酸镁水泥水化反应后期,当硝酸铅掺量达到10%以上时,在水化产物中出现了较为明显的Pb2P2O7的衍射峰。复合磷酸盐磷酸镁水泥固化铅离子的浸出毒性试验结果(43μg/L)远低于国家标准要求(5mg/L)。     

碳纳米管对磷酸镁水泥的性能影响研究

研究了不同掺量的碳纳米管对磷酸镁水泥(MPC)力学性能和导电性能的影响,并结合压汞法,XRD和FTIP分析其组分与微观结构变化。结果表明,随着碳纳米管掺量的增加,磷酸镁水泥的抗压强度先增加后降低,掺量为0.03%时达到最佳。随着碳纳米管掺量增加,MPC电阻率逐渐降低,而孔隙率增加。一定掺量的纳米碳管可以促进磷酸镁水泥的水化,但没有新的水化产物生成。     

磷酸镁水泥水化热的影响因素研究

采用八通道微量热仪研究了不同m(M)/m(P)(氧化镁和磷酸二氢钾质量比)比值、水胶比(W/B)、硼砂掺量、粉煤灰掺量和磷酸盐种类对磷酸镁水泥水化热的影响规律。实验结果表明,磷酸镁水泥的水化存在吸热和放热两个过程,包含一个吸热谷和两个放热峰,吸热谷产生于磷酸盐的溶解,放热峰与氧化镁溶于酸性溶液及产物的形成有关;提高m(M)/m(P)比值、水胶比、硼砂掺量和粉煤灰掺量都会降低磷酸镁水泥水化的放热速率和放热量;以磷酸二氢铵、磷酸二氢钠、磷酸二氢钾为磷酸盐所制备的磷酸镁水泥的水化放热峰峰值和放热量分别达到了0.430714,0.145677,0.194626 W和1198.949,452.798,902.872J,表明了磷酸盐种类对磷酸镁水泥水化热和放热速率有显著的影响,这与三者的溶解度和pH值有关。     

缓凝剂硼砂对磷酸镁水泥水化硬化特性的影响

为了探讨缓凝剂硼砂(B)对磷酸镁水泥(MPC)的作用机理,测试和分析了不同掺量硼砂(B)的磷酸镁水泥(MPC)浆体的凝结时间、pH值、体系温度以及硬化体的强度和微观结构。结果表明:硼砂在一定掺量范围内对磷酸镁水泥(MPC)浆体有较明显的吸热降温促进作用和调节pH值作用,两种作用均可减慢浆体的水化反应速度且进一步影响硬化体的微观结构形貌和强度。由此推论硼砂在磷酸镁水泥(MPC)浆体中,除在MgO表面形成保护膜外,还通过降低体系温度和调节浆体pH值进而减慢水化反应速度来延缓浆体的凝结,随着硼砂(B)掺量的变化,不同因素起主导作用。     

EVA乳液对磷酸镁水泥性能的影响研究

选择原材料是改善磷酸镁水泥性能的重要方法,为扩大磷酸镁水泥的应用范围,对EVA乳液改性磷酸镁水泥进行研究,结果表明,EVA乳液的掺加对磷酸镁水泥的凝结时间与流动性影响小;磷酸镁水泥的抗压与抗折强度均随着EVA乳液掺量的增大,表现出先提高后降低的趋势,但存在不同的适宜掺量;EVA乳液显著增大磷酸镁水泥的粘结强度与断裂能;微观分析表明EVA乳液不改变磷酸镁水泥水化产物类型,但改变水化反应速度,影响水化产物形貌,其中MgNH4PO4·6H2O主要以柱状存在,并且结构更加致密。     

磷酸镁水泥修补材料耐磨性影响因素研究

以重烧MgO和磷酸二氢铵为主要原料制备磷酸镁水泥修补材料,研究了氧化镁与磷酸二氢铵的比值(M/P)、水胶比(W/B)、硼砂掺量、粉煤灰掺量及龄期对磷酸镁水泥石耐磨性的影响,采用X射线衍射分析和扫描电镜探讨不同龄期水化产物的物相组成及结构。结果表明,M/P=4时磷酸镁水泥石耐磨性最强;7d内磷酸镁水泥石耐磨性随W/B增大而减弱;掺入硼砂和粉煤灰都会影响磷酸镁水泥石的耐磨性,且掺量越大耐磨性越差;磷酸镁水泥石耐磨性随龄期延长而提升。     

粉煤灰掺量对轻烧氧化镁基制备3d打印用磷酸镁水泥性能的影响

以实现轻烧氧化镁为原料制备低碳磷酸镁水泥材料的3d打印为目标,采用自主研发的混搅挤功能一化建筑3d打印设备,探究了不同粉煤灰掺量对以轻烧氧化镁为基制备磷酸镁水泥材料性能与打印性能的影响规律,并结合XRD与SEM微观试验进一步分析粉煤灰对其水化产物及晶体样貌的影响。结果表明：与重烧氧化镁相比,由轻烧氧化镁制备磷酸镁水泥的凝结时间大幅缩短;粉煤灰的加入对材料凝结时间影响较小,均在2～3 min左右,但对抗压强度与界面粘结强度有负面影响,当粉煤灰掺量为磷酸镁水泥质量的30%时,抗压强度及界面粘结强度分别下降约34.24%、48.94%;粉煤灰掺量在20%以内时,可有效改善轻烧氧化镁基磷酸镁水泥材料的干缩率,提高体积稳定性;粉煤灰中的活性物质参与水化反应,生成的水化产物与磷酸镁水泥展现出良好的化学相容性,使结构内部更为密实;当粉煤灰掺量为20%～25%时,制备的3d打印用轻烧氧化镁基磷酸镁水泥具有良好的工作性能、体积稳定性能、挤出性能以及建造性能,且满足3d打印对水泥基材料的力学要求。     

膨润土对磷酸镁水泥性能的影响

采用膨润土等量取代磷酸镁水泥的方法,研究了膨润土对磷酸镁水泥流动度、凝结时间、强度、水化热和早期收缩的影响,并对水化产物进行了分析与讨论。结果表明,膨润土降低了磷酸镁水泥的流动度、凝结时间和强度,为保证施工的可操作性,其掺量应控制在10%以内;膨润土有效降低了磷酸镁水泥的放热速率和放热量,减少了其早期收缩;掺有膨润土的磷酸镁水泥的水化产物中存在膨润土的主要成分蒙脱石和石英;膨润土影响了磷酸镁水泥的水化过程、水化产物的数量及其结晶程度。     

粉煤灰改性磷酸镁水泥性能及机理分析

以粉煤灰、MgO和KH₂PO₄为原料制备磷酸镁水泥(MPC)。测定MPC在不同粉煤灰掺量下的抗压强度、抗折强度、凝结时间、孔隙率,并分析其微观结构。研究结果表明：MPC抗压强度随粉煤灰掺量的增加先升高后降低,掺量为20%时强度最大为34 MPa,抗折强度随粉煤灰掺量的增加而降低,韧性随粉煤灰掺量的增加而降低;粉煤灰改善了MPC孔结构,粉煤灰掺量为40%时MPC孔隙率降低了67.2%;粉煤灰延长了MPC凝结时间,粉煤灰掺量为40%时MPC凝结时间延长至13.7 min;随着粉煤灰掺量的增加水化产物MgKPO₄·6H₂O(MKP)生成量先增多后减少,粉煤灰掺量20%时MKP生成量最大。粉煤灰对MPC强度的影响主要取决于MKP生成量。     

含铬熟料的烧成、水化及其浸出毒性

为探索水泥窑协同处置含铬固体废弃物的可行性,通过测定熟料的f-CaO含量、强度、铬浸出浓度,以及分析熟料的矿物、水化产物和水化放热,研究了CrO3对熟料烧成、水化及浸出毒性的影响规律及机制。结果表明:当CrO3掺量低于2%时,熟料的f-CaO含量和3d、28d、90d强度随掺量的变化不明显;Cr(Ⅵ)/∑Cr浸出浓度随CrO3掺量增加而增大,随养护龄期延长而减小。当CrO3掺量小于0.25%时,熟料Cr(Ⅵ)浸出浓度均低于0.05mg/L,符合Ⅱ类地表水环境质量标准限值;当CrO3掺量较高时,抑制C3S形成,并显著延缓水化;熟料对铬的固化可归因于熟料矿物和水化产物对铬的固溶和包裹。掺加少量CrO3对熟料烧成、水化、性能均无不利影响,产品的环境安全性能够得到保证,水泥窑协同处置含铬废弃物是值得深入研究的技术途径。     

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.……     

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.     

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.     

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