纳米碳酸钙、铜粒子混合物用作润滑油添加剂的研究

本研究采用纳米碳酸钙和铜粒子混合物作为添加剂加入润滑油中,选择合适的表面活性剂制备含纳米碳酸钙和纳米铜粒子混合物添加剂的润滑油.采用四球摩擦磨损试验机测定含纳米碳酸钙、纳米铜粒子添加剂的润滑油的摩擦学性能;使用扫描电子显微镜(SEM)和能谱分析(EDS)等观察分析磨损钢球表面的磨痕形貌、化学元素和纳米粒子形态.结果表明,纳米碳酸钙、纳米铜的混合粒子的最佳添加量为:总添加量Wt(CaCO3 Cu)%=0.6%,WtCaCO3%:WtCu%=1:1;该润滑油具有最佳的抗磨、减摩性能.研究表明,含纳米碳酸钙、纳米铜粒子添加剂的润滑油的抗磨、减摩机理与纳米粒子存在形态相关.     

含纳米CaCO3,Cu混合物添加剂润滑油的研究

采用纳米碳酸钙、纳米铜粒子混合物作为润滑油添加剂.选择合适的表面活性剂制备含纳米碳酸钙和纳米铜粒子混合物添加剂的润滑油.利用四球摩擦磨损试验机考察含纳米碳酸钙、纳米铜粒子添加剂的润滑油的摩擦学性能;用扫描电子显微镜(SEM)观察表面磨痕的形貌.用原子力显微镜和扫描电子显微镜(SEM)观察分析在磨损表面纳米粒子的形态与分布.研究结果表明,纳米碳酸钙、纳米铜的粒子混合物的最佳添加量为:纳米碳酸钙与纳米铜的总添加量的质量分数为0.6%,纳米碳酸钙与纳米铜的质量分数之比为1∶1;该润滑油具有最佳的摩擦学性能.研究还表明,润滑油中纳米碳酸钙、纳米铜粒子混合物添加剂的优良摩擦学性能与纳米粒子在表面存在形态相关.     

含纳米碳酸钙粒子润滑油的摩擦学性能研究

研究了将粒径约为40nm的纳米碳酸钙粒子作为添加剂加入40CD润滑油中,采用四球摩擦磨损试验机测定含纳米碳酸钙粒子的润滑油的摩擦学性能;利用扫描电子显微镜、X射线光电子能谱仪观察与分析磨斑表面形貌、元素的状态等.结果表明,含0.6%纳米碳酸钙的润滑油具有最佳的抗磨减摩性能;文中对抗磨减摩机理进行了探讨.     

纳米锑颗粒作为液压油添加剂的摩擦学性能

为了研究纳米锑颗粒作为润滑油添加剂的润滑摩擦学性能,充分发挥其减磨、抗磨效果,采用CFT-1型材料性能测试仪对比研究了不同载荷下纳米锑粒子作为液压油添加剂的摩擦学性能,通过SEM对试样摩擦表面进行了形貌分析,利用EDX进行了磨痕表面元素分析.结果表明:不同载荷下纳米锑颗粒在液压油中的最佳添加量不同,重载荷下纳米锑粒子表现出优良的抗磨减摩性能;纳米锑粒子在一定程度上可以提高液压油的抗磨减摩性能,这是由于磨痕表面形成了含锑元素的表面膜,起到良好的抗磨减摩效果.     

纳米铜添加剂对重载车辆润滑油摩擦学性能影响的研究

采用化学反应法制备了表面修饰的纳米铜微粉,采用超声分散工艺分散于16#机油基础油中,利用T-11摩擦磨损实验机进行摩擦磨损试验。试验结果表明：不含纳米Cu的减摩添加剂和含纳米Cu的减摩添加剂添加到16#机油中,磨损量分别减少了19％、33％,减摩性能分别提高59％、86％。能谱分析表明磨痕表面不均匀的分布有铜元素,说明添加剂中的纳米铜在磨痕表面沉积,起到改善润滑油抗磨性能的作用。     

纳米坡缕石润滑油添加剂对灰铸铁HT200摩擦磨损性能的影响

制备坡缕石纳米粒子添加到150N基础油的润滑油体系,在MMU-10G摩擦磨损试验机上分别对该纳米粒子润滑油体系和纯150N基础油,在混合润滑条件下的铸铁HT200试样对摩时的摩擦磨损性能进行研究,并用SEM和金相显微镜对磨损表面进行观察和分析,借助EDX测定试样表面成分的变化,探讨摩擦磨损性能变化的机理。结果表明:自制备的用KH550硅烷偶联剂球磨修饰的坡缕石纳米粒子在基础油中分散性良好,在该润滑剂润滑条件下对摩的试样表面生成了自修复膜层,其磨损量明显减小,失重量下降约25.2%,平均摩擦系数下降约32.3%。     

复合Al_2O_3-SiO_2纳米颗粒的摩擦学性能研究

以硅烷偶联剂为改性剂对复合Al2O3-SiO2纳米颗粒进行原位改性,实现其在润滑油中均匀稳定的单分散。将改性后的复合Al2O3-SiO2纳米颗粒分别按质量分数为0、0.05%、0.1%、0.5%、1.0%的量加入到润滑油中制成试样,进行四球试验和止推圈试验。对摩擦实验中的摩擦系数、磨斑直径、磨损量、摩擦副表面形貌进行分析。结果表明:当复合Al2O3-SiO2纳米颗粒添加质量分数为0.5%时,摩擦系数和磨斑直径最小,止推圈的磨损量出现负磨损,摩擦表面的磨痕明显的变浅、变窄。说明摩擦过程中,复合Al2O3-SiO2纳米颗粒沉积在摩擦副表面,形成一层保护膜有效的保护了摩擦表面,抗磨减摩作用显著。     

原位合成纳米铜润滑油的分散及摩擦学性能

为了获得减摩性优良的纳米铜润滑油,采用自制的油幕喷淋循环电爆装置并添加不同浓度的分散剂丁二酸二异辛酯原位合成纳米铜润滑油,以提高纳米铜颗粒的分散性.采用紫外-可见分光光度计、静置沉降法、X射线衍射仪和透射电镜分析了纳米铜颗粒的分散稳定性能;采用磨损试验评价了纳米铜润滑油的减摩性能;采用扫描电镜观察了盘基体的磨痕形貌.结果表明:纳米铜颗粒的分散稳定性能随丁二酸二异辛酯浓度的增大呈先增大后减少的变化规律,当分散剂浓度为3％时,纳米铜润滑油悬浮液吸光度最大,沉降率最小,分散稳定性能较好,同时其摩擦系数最小,钢球的磨斑直径最小,减摩性能较好.     

Fe3O4@CuO磁流体的制备和边界润滑性能

采用化学共沉淀法合成了纳米Fe₃O₄和纳米Fe₃O₄@CuO粒子。采用场发射透射电镜(FETEM)、X射线衍射仪(XRD)、振动样品磁强计(VSM)和傅里叶变换红外光谱仪(FTIR)对纳米粒子进行表征。采用表面活性剂法制备了不同粒子含量的PAO3磁流体。利用磁流体对外加磁场的响应特性和紫外分光光度计对磁流体分散性进行了表征。采用摩擦副为12CrNi4A和Si₃N₄的UMT-3往复摩擦磨损试验机对磁流体的摩擦学性能进行了评估。摩擦实验结果表明,含纳米Fe₃O₄粒子的PAO3基磁流体的润滑效果比较差。而质量分数为1%的纳米PAO3基Fe₃O₄@CuO粒子磁流体润滑时的摩擦系数相比于PAO3油润滑降低了29.6%,磨痕宽度降低了49.6%。从磨痕表面分析来看,这得益于CuO的摩擦烧结作用,在摩擦表面形成了有效的摩擦膜并修复磨损表面。     

坡缕石/铜复合纳米粉体对HT200摩擦副的摩擦学性能

用共混法制备1∶1的坡缕石/铜复合纳米粉体,经表面修饰后按质量比2%添加到150N基础油中,制备出含复合纳米材料添加剂的润滑油体系。用MMU-10G摩擦磨损试验机测试该润滑油添加剂对HT200对磨试样的摩擦学性能,并用高精度电子天平测定试件的失重量以评定其耐磨性能。用扫描电镜SEM、EDX等分析了摩擦磨损试验后表面成分与形貌的变化,并分析了摩擦学性能变化的机理。结果表明:制备的坡缕石/铜复合纳米粉体在基础油中分散性良好,颗粒大小不超过200nm,能明显提高摩擦副的减摩抗磨性能,平均摩擦因数下降19.1%,总磨损量下降44%,试件表面生成了含坡缕石特征元素和铜元素的自修复膜层,这是纳米坡缕石和纳米铜粒子共同作用的结果。     

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.     

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.……     

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.     

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.