磁流变液材料的研究进展和应用前景

从材料的角度较为全面地综述了国内外磁流变液的研究状况,评述了国内外对磁流变材料的主要研究热点,内容涉及磁流变液的流变机理、性能以及磁性粒子、载液和添加剂等组成对磁流变液性能的影响,并展望了其应用前景。     

固液复合润滑体系的摩擦学行为研究进展

随着空间高新技术工业的日益发展,对高性能润滑材料的要求日益增强,单一的润滑材料已经无法满足其发展需要求。固液复合润滑体系相比单一润滑材料具有更优异的摩擦学性能,已被广泛的开发和利用在不同的科学技术领域。对近年来固液复合润滑体系的研究进展和现状进行综述。     

汽车用磁流变液离合器中的磁流变液性能分析

介绍了磁流变液这种智能材料的组成、特性及流变机理,并通过实验对汽车磁流变液离合器系统中磁流变液磁扭转力与电流及其自身磁粉固含量之间的曲线关系进行了分析.     

磁流变液的研究

磁流变液是一种新兴的液体传动介质 ,它具有优越的性能 ,被广泛用于液压传动 ,汽车、制造、机械加工等领域。本文着重介绍了磁流变液的制备及其国内外进展情况     

磁流变液智能流体研究进展、应用及展望

通过回顾磁流变液智能流体的组成及制备方法,分析了磁流变液智能流体主要流变机理以及在工程中的应用前景,并着重介绍了磁流变液在油气田开发中的研究进展。基于磁流变液特点、应用环境以及使用成本等因素,指出了磁流变液智能流体未来向高温稳定、可循环利用以及环境友好发展的新趋势。     

磁流变液智能流体研究进展、应用及展望

通过回顾磁流变液智能流体的组成及制备方法,分析了磁流变液智能流体主要流变机理以及在工程中的应用前景,并着重介绍了磁流变液在油气田开发中的研究进展。基于磁流变液特点、应用环境以及使用成本等因素,指出了磁流变液智能流体未来向高温稳定、可循环利用以及环境友好发展的新趋势。     

纳米颗粒增强摩擦材料摩擦学性能研究

以丁腈橡胶改性酚醛树脂为基体,芳纶纤维、玻璃纤维为增强纤维,选用不同类型的纳米颗粒作为填料设计摩擦材料组分配比,并通过热压烧结制备摩擦材料。通过摩擦磨损试验机测试其在干摩擦条件下的摩擦学性能,并用扫描电镜(SEM)对材料的磨损形貌进行观察分析,以研究不同类型的纳米颗粒对摩擦材料性能的影响。研究表明:在干摩擦条件下,经过纳米颗粒改性的摩擦材料摩擦系数、硬度比未改性的材料有不同程度的提高,同时磨损率有很大程度的降低;纳米颗粒改性的摩擦材料摩擦系数、磨损率变化趋势具有一致性,均随着实验载荷、滑动速度的增大而逐渐减小;纳米颗粒改性后的摩擦材料磨损机理表现为疲劳磨损与磨粒磨损并存,而未改性的材料磨损机理主要表现为疲劳磨损。     

基于 FLUENT 的磁流变液的流动行为仿真

对磁流变液在不同条件下的流动行为进行分析,利用 Gambit 建立了磁流变液的俯视二维简化模型并对其进行了网格划分。应用 FLUENT 对不同入口速度和障碍物大小条件下磁流变液中基础油的流动行为进行了仿真模拟,得出不同障碍大小和入口速度下的速率变化云图,分析表明仿真效果能较好的模拟磁流变液的真实流动状态,能较好的解释磁流变液在不同剪切速率和链聚集程度下的流动行为。     

MAF-6作为无水钙基润滑脂添加剂的摩擦学性能研究

以金属多氮唑骨架材料(MAF-6)作为润滑脂固体添加剂,考察其在润滑脂中的摩擦学性能.结果表明,MAF-6作为添加剂能有效提高基础脂的摩擦学性能,在高往复频率、高运行载荷和延长运行时间的条件下,MAF-6脂能够保持优异的减摩抗磨性能.研究其润滑机制发现,在运行过程中,拥有柔性晶体结构的球状MAF-6能够粘附在金属表面,...     

圆盘式磁流变液传动装置传递力矩分析与测试

针对所设计的一种圆盘式磁流变液传动装置进行了磁流变液传动的转矩分析与实验测试研究。以B ingham模型为基础,推导出转矩、转速及磁感应强度之间的数学关系式;应用有限元数值分析,研究了圆盘式磁流变液传动装置在不同电流强度下磁感应强度沿半径方向的分布规律,进一步利用数据拟合的方法确定了磁感应强度、电流和半径之间的关系,将拟合的表达式代入转矩的计算表达式,最终得到传递转矩和电流强度之间的函数关系式,并进行了相关的实验测试。对实测转矩数据与理论分析得到的转矩数据进行了对比分析及相对误差分析。     

Experimental study of the influences of the pellet shape on the bulk density and the frictional behavior of polypropylene

Bulk solids are the raw material for almost every polymeric thermoplastic product. Their properties determine the quality of solids conveying and also influence the melting behavior of the material in processing units. This study investigates the influence of pressure and temperature on the bulk density of two thermoplastic polypropylene pellets of different shapes. Furthermore, the external friction dependent on temperature and pressure of those materials is examined at conditions usually occurring in the solids conveying zone of smooth barrel plasticating units. The experiments are carried out using a tribometer for polymer pellets which was adapted for these tests by making the sample chamber, the piston, and the cylindrical roll heatable. The tests show that long cylindrical pellets exhibit low bulk densities at low pressure and temperature, which can be increased dramatically—even above the values of spheroidal pellets—as those parameters increase. Moreover, the external coefficient of friction is always higher for the long cylinders and strongly dependent on the temperature. Those facts add up and can cause a higher output of single‐screw extruders. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42197.     

Frictional characteristics and vibration behavior of silicone rubber powders modified resin-based friction materials

Resin-based friction materials (RFM) are widely used in vehicle brakes. However, the thermosetting resins and rigid fillers in RFM have low toughness and produce strong vibration behavior during continuous friction processes, which adversely affects the equipment. This work proposed a method for co-blending modification of RFM with silicone rubber powders (SRP) to mitigate friction-induced vibrations, and the mechanism of silicone rubber modification on the vibrational behavior of RFM during friction was investigated. The results demonstrate that SRP-modified RFM exhibit excellent damping property and frictional characteristics. SRP modification improves the stability of the coefficient of friction and reduces fatigue wear. The wear rate of RFM modified with 10 wt% SRP reduced by 29% and the average amplitude of friction-induced vibration decreased by 35.5% compared to unmodified RFM. This work provides both theoretical and practical foundations for designing and developing RFM with high damping, low wear, and low vibration characteristic.     

Synthesis of a water‐soluble,rubber seed oil–based sulfonate and its tribological properties as a water‐based lubricant additive

A novel, water‐based oleic acid (OA)/2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid (AMPS) copolymer was successfully synthesized as a water‐based lubricant additive. The OA‐AMPS copolymer was characterized by Fourier transform infrared and proton NMR spectroscopies and then used as a lubricant additive in water. The lubrication properties of water‐miscible cutting fluids with the OA‐AMPS copolymer additive were investigated using a four‐ball friction tester. The surface of the wear scars was explored using scanning electron microscopy and X‐ray photoelectron spectroscopy. The addition of the synthesized OA‐AMPS copolymer improved the friction coefficient and wear scar diameter of water. The maximum nonseizure load increased from 95 to 431 N, and the anticorrosion ability on copper was categorized as 1b. Good antiwear and friction‐reducing properties for water were observed and attributed to the absorption and tribochemical films composed of iron oxide and ferrous disulfide. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46119.     

Temperature effect on mechanical strength and frictional properties of polytetrafluoroethylene-based core-shell nanocomposites

Polytetrafluoroethylene (PTFE) has shown an outstanding lubricity as a solid lubricant, but its application is limited due to its low-mechanical strength and high-wear rate. In this study, core-shell nanoparticles were synthesized using PTFE as the core and polymethylmethacrylate (PMMA) as the shell. The formed core-shell nanocomposites by leveraging the core-shell nanoparticles as basic structural units exhibit remarkable enhancement on uniformity, tensile strength, and wear resistance, compared to mechanically mixed composites with the same composition. Our experiments demonstrated the following results: (1) Owing to the excellent uniformity, the maximum tensile strength of core-shell nanocomposites was 62 MPa, three times higher than that of mechanically mixed composites. (2) The composite matrix formed by PMMA shell had better reinforcement and protection effect on inner PTFE phase, resulting in a reduced wear rate of 0.3 × 10⁻⁵ mm³/(N m), one order of magnitude lower than that of mechanically mixed composites. (3) The friction coefficient and interfacial mechanical properties of the core-shell nanocomposites at different temperatures have been systematically studied to get insights into lubrication mechanisms. It is proved that the temperature can decrease the modulus and increase the interfacial adhesion as well as the loss tangent of the core-shell nanocomposites, thus affecting the lubrication properties in multiple ways.     

Preparation and properties of wear-resistant and flame-retardant polyphenylsulfoneurea/monomer casting nylon copolymers

A poly(phenylsulfone)-urea (PPSUU) macro-activator is synthesized by in situ anionic polymerization of 4,4′-diaminodiphenylsulfone and hexamethylene diisocyanate. The PPSUU segment is embedded into the nylon molecular chain through copolymerization to improve the wear resistance and flame retardancy of monomer cast nylon 6 (MC PA6) materials. The mechanical properties, thermal stability, friction and wear properties and combustion heat release rate of copolymers with different macro-activator contents are tested. Results indicate that a small amount of PPSUU can improve the wear resistance and impact properties of nylon materials. The wear loss of MC nylon is 54.8% less than pure MC nylon from 1.049 × 10⁻⁸ to 0.474 × 10⁻⁸ g/Nm with 6 wt% PPSUU. Moreover, better flame retardancy is verified. The peak of HRR reduced 36.8% from 654 to 413 kw/m² with 4 wt% PPSUU, accompanied by advanced ignition time and flame extinction time, thus reducing the risk of fire.     

Tribological and corrosion performance of epoxy resin composite coatings reinforced with graphene oxide and fly ash cenospheres

In this work, a novel graphene oxide (GO)-fly ash cenospheres (FACs) hybrid fillers was introduced to improve the wear and corrosive resistance of epoxy resin (ER) composite coatings. The tribological behavior and the corrosion performance of three kinds of coatings (pure ER, GO/ER and GO-FACs/ER coatings) were studied and the reinforced mechanisms of coatings filled by different fillers were analyzed. The friction coefficient and wear rate of the ER coatings were decreased with the addition of GO-FACs hybrids. The scanning electron microscope images showed that the dispersibility and compatibility of GO-FACs hybrids were effectively improved compared with that of GO sheet. The water contact angle examination indicated that the hydrophobicity of the GO-FACs/ER coatings increased. The electrochemical impedance spectroscopy (EIS) results demonstrated that the GO-FACs/ER coatings have better anticorrosion performance compared with the pure ER coatings and the GO/ER coatings. The hydrophobic surface and the well dispersed fillers constitute the dual barrier to resist the corrosion medium.     

Preventing thermal degradation of PVC insulation by mixtures of cross-linking agents and antioxidants

Poly(vinyl chloride) (PVC) is widely used—in spite of HCl formed from it at elevated temperatures. PVC wire and cable insulation has poor thermal stability, causing the plasticizer to separate from the PVC chains and produce an oily residue, lowering the tensile elongation at break and thus increasing brittleness. One uses cross-linking agents and antioxidants, as well as mixtures of both, to improve the thermal stability of the plasticizer and tensile properties of PVC after thermal exposure. We performed tensile tests, tribological tests, profilometry, scanning electron microscopy (SEM), and water absorption determination before and after thermal exposure at 136 °C for 1 week. After adding the agents, elongation at break increased by 10 to 20% while the wear rate and water absorption were lower than for the control sample. Less voids are seen in the SEM images after adding these two kinds of agents. The thermal resistance of the PVC cable insulation is best enhanced by combinations of cross-linking agents and antioxidants. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48816.     

Preparation and tribological behavior of polytetrafluoroethylene/metal mesh composites with sandwich structure

Polytetrafluoroethylene (PTFE) owns an excellent self-lubricating performance, but its wear rate is very high due to the large-scale spalling of the matrix in the friction. In this paper, A new kind of PTFE composites with sandwich structure was prepared by layer-press technology, whose middle layer is filled with metal mesh. The influence of the mesh structure and mesh density of middle metal layer on tribological properties of composites were researched in detail. The results revealled that the metal mesh located in the composites can efficiently prevent the large-scale spalling of PTFE, which induces the sample of PTFE/500# plain woven dutch metal mesh (PTFE-500#PWD) to have a lower wear rate (9 × 10⁻⁵ mm³/Nm) and COF (0.106) under the fixed experimental condition. The prepared PTFE/metal mesh composites reveal excellent anti-friction and anti-wear performance, which can be used to fabricate a new kind of self-lubricating materials.     

Effect of adding different silane coupling agents on metal friction and wear in mixing process

The function of silane coupling agent in rubber mixing field is to combine inorganic matrix with rubber organic matrix. Silica is commonly used in the rubber mixing field to strengthen rubber. The size and amount of silica aggregates in the mixing process are important factors affecting the wear of the mixing chamber. The wear of the mixing chamber would lead to a increasing gap between the mixer chamber and the rotor, which caused the mixing efficiency reducing. It also affected the dispersion effect, then affected the mechanical and physical properties of the vulcanized rubber. In this paper, the effects of rubber compound on metal friction and wear were studied by using four silane coupling agents commonly used in rubber mixing field. The experiment was carried out at 15°C, and the attention should be paid to drying during sample preparation to avoid the deviation of the experiment caused by hydrolysis of silane coupling agent. The results showed that silanization reaction occured between silica and silane coupling agent in the mixing process. The mixing temperature was usually maintained at 145 to 155°C for 1 min in the mixer, and the silanization reaction rate was the fastest during this time. We took this rubber compound as the research object and studied the friction and wear of the rubber compound on the mixing chamber in the mixing process. The products of the silylation reaction are alcohol and water. This paper studies the corrosion and abrasion of the mixing chamber by water at high temperatures. In the mixing process, abrasive wear was the main wear form, but the corrosion wear caused by high temperature steam still occupied a large proportion.