Effects of Electric Potentials on Tribological Properties of SiC/HT200 Pairs in NaOH Solutions

On a self-developed circular-translation polishing machine, the influence of different electric potentials on the friction coefficient and wear properties of SiC/HT200 friction pair, which contacted as one electrode, were studied in NaOH solutions. The results show that the friction coefficient of SiC/HT200 pair is 0.25 under no externally applied potential; but it decreases to 0.23 while applying +3 V polarization potential on the pair; in contrast, it increases to 0.30 when applying -3 V polarization potential on the pair. And the polished SiC surface under +3 V potential is much smoother, while there are clear ploughing marks and adhesive region on the polished SiC surface under zero and -3 V potential, respectively. The mixed tribo-electrochemical friction model has been proposed and the mechanisms of the electric effects on the tribological properties of SiC/HT200 friction pair in NaOH electrolyte are addressed. Results and discussion show that the anodic passivation technique may be used for hastening the running-in process of SiC/Fe friction pairs, as well as for polishing SiC to increase its materials removal efficiency while maintaining good surface quality.     

吸湿发热纤维混纺针织物耐磨性和悬垂性研究

研究吸湿发热纤维混纺针织物的力学性能,就其耐磨性和悬垂性与纯棉织物、涤棉混纺织物做了对比,实验结果显示,吸湿发热纤维混纺针织物的耐磨性、悬垂性均优于纯棉,与涤棉混纺织物相比略差。通过对吸湿发热纤维混纺针织物力学性能的测试分析,为后续针织物的研究奠定基础。     

金属材料FV520B冲蚀模型的建立与验证

为了用数学的方式描述金属材料的冲蚀率随靶材属性、颗粒属性、环境因素的变化规律,从颗粒冲击靶材的碰撞过程入手,通过求解颗粒运动方程和碰撞的能量方程,建立了基于微切削和变形磨损的塑性材料冲蚀模型。借助金属材料FV520B的正交冲蚀试验结果,利用回归分析法获得FV520B冲蚀率计算模型,并通过方差分析和单因素冲蚀试验对计算模型进行了验证。方差分析结果表明,该冲蚀率计算模型非常显著,由模型获得的冲蚀率计算值与单因素试验结果吻合程度较高,说明该模型在预测金属材料FV520B不同环境下的冲蚀磨损时具有较好的适应性和可靠性,研究结果对叶轮材料FV520B冲蚀磨损寿命的评估具有指导意义。     

3000m起重铺管船铺管作业率研究

针对3 000 m起重铺管船的运动性能,对其铺管作业率做了相应的研究。将模型试验得出的规则波运动响应的每个自由度的n个数据点通过样条差值的方法编写到不规则波响应谱中,并采用变步长勒让德-高斯积分的方法求解出船舶不规则波运行的单幅最大值。同时,与SESAM程序软件的计算结果作对比,经研究,验证了该计算方法的有效性。最后,将计算出的一系列单幅最大值与相应校准值作比较,根据海况资料,将所有满足条件的一系列不规则波的发生概率相加,则起重铺管船在特定工况下的铺管作业率得到了求解。     

不同工况下丁腈橡胶的摩擦磨损机理

为了合理选择螺杆泵定子橡胶材料以提高螺杆泵的使用寿命,分析了不同工况下丁腈橡胶与金属配副的摩擦磨损机理.采用MPV-600环块式摩擦磨损试验机对不同炭黑质量分数的丁腈橡胶在变载荷情况下进行摩擦磨损试验,利用体视显微镜观察橡胶磨损后的表面形貌,使用红外光谱仪分析表面官能团变化.试验结果表明:干摩擦情况下,磨损量在一定炭黑质量分数范围内随其增加而减小,磨损机制为黏着磨损和磨粒磨损;水润滑情况下,由于水的润滑及冷却作用,炭黑质量分数适中的橡胶耐磨性最好,磨损机制为磨粒磨损;原油润滑低载荷情况下,磨损量几乎不受炭黑质量分数的影响,而高载荷情况下,炭黑质量分数越高,磨损量越小,其磨损机制以腐蚀磨损为主.     

考虑扭转效应的平面不规则大底盘单塔楼减震性能分析

对平面不规则大底盘单塔楼进行隔震分析,分别将层间隔震支座及基础隔震支座应用于此类结构,分别建立层间隔震及基础隔震以及传统的抗震结构模型,利用有限元软件SAP2000对某单塔楼结构在罕遇地震作用下进行动力时程分析.通过楼层剪力,层间位移以及楼层加速度对比,表明采用隔震装置结构的减震效果明显,同时表明由结构平面布置不规则所导致的扭转效应引起我们高度重视.     

改性UHMWPE塑料的摩擦磨损性能研究

分别研究MoS2、PTFE和石墨对UHMWPE耐摩擦性能的影响。结果表明:在载荷200 N,转速400 r/min的试验条件下,UHMWPE/石墨、UHMWPE、UHMWPE/MoS2和UHMWPE/PTFE的平均摩擦系数分别为0.27,0.30,0.35和0.39。掺杂石墨(质量分数9%)降低了UHMWPE的摩擦系数,在试验过程中减少了由于摩擦而产生的热量,从而提高了UHMWPE/石墨复合材料的耐磨性能。     

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.     

Hybrid polymer matrix composite (UHMWPE-HPMC) as solid particle erosion resistant coating for sharp pipe elbows using numerical simulation and experimental analysis

A hybrid polymer matrix composite coating, resistant to solid particle erosion inside sharp elbows, consisting interlocking chains of molecules with the ability to deflect the surface impact stress and to uniformly distribute stresses along the hard-ceramic reinforcement mixture surface was developed. Formulated mixture of ceramic reinforcement particles mixtures (alumina, tungsten carbide, and silicon carbide) with polymer coupling agents; to increase adhesion to the metal surface, led to 600–700 HVN in ternary and 500–550 HVN in binary mixtures. This behavior coincides with high shear strength of 70–76 MPa, Young's and shear modulus of 8.86 and 13.4 GPa in ternary 15%Al₂O₃-5%WC-10%SiC, respectively. The low erosion weight loss of 0.1% and small coefficient of friction near 0.18 indicates the significant wear resistance of the ternary sample. The electron microscopic micrographs determined the dense smooth coating surfaces with adhesive interfaces with the substrate.     

Sodium citrate-assisted synthesis of nano-manganese oxide on carbon fiber for enhancing the mechanical and frictional performances of carbon fiber-reinforced resin matrix composites

Aiming to enhance the carbon fiber (CF)/resin interfacial adhesion, this report describes the novel application of sodium citrate (SC) as an auxiliary reducing agent and surface regulator to control the morphology of nano-manganese dioxide (MnO₂) on the CF surface. The composites were fabricated by means of controlling the molar concentration ratio of SC to Mn source (0:1, 1:3, 1:2, and 1:1) in hydrothermal synthesis. The results reveal that MnO₂ nanosheets on the CF surface become denser as the concentration of SC is 1/3 of Mn source, which makes advance to the surface roughness and surface energy of CF. Simultaneously, the tensile strength of as-prepared composite is increased by 52.8%. The homologous friction coefficient tends to be high and stable and the wear volume is significantly reduced by 63.8 and 26.5% under the applied loads of 3 and 5 N in contrast with the original composites prepared without SC. As a result, it can be inferred that SC plays a crucial role in enhancing the interfacial bonding strength between the CF and matrix, providing insights into the interface control of CF-reinforced resin matrix composites.