Ni-Cu-Re合金自生氧化膜的减摩机理

用旋转式高温销盘摩擦试验机测定了 Ni、Ni-Re,Ni-Cu、Cu-Re 及 Ni-Cu-Re 等合金摩擦系数随温度的变化;用 X 射线测定了磨屑及氧化层、Ni-Cu-Re 550℃的挥发物结构;能谱测定了磨屑、氧化膜及近表层成分,还进行了静态氧化实验,试验发现高温摩擦实验后样品近表层有富 Re 层,它不利于氧化膜的形成,但降低了合金的氧化速度,提高了耐磨性,试验结果还表明了Ni-Cu-Re 系高温摩擦系数较低(0.2-0.3),原因是 Cu,Re 共同作用形成易挥发性氧化物起的润滑作用,提出了氧化膜的减摩模型。     

Experimental analysis of nanomechanics of spherical titanium oxide nanooils in reducing friction

This work explores the nanomechanics of sphere titanium oxide nanooils in reducing friction between two pieces of cast iron. A friction test is performed using an ATE-77 Reciprocal Tribological Tester made by Cameron-Plint Tribology Limited, England. The friction between two pieces of cast iron was determined 25-135 degrees C using home-made titanium oxide nanooils. In elastohydrodynamic lubrication (EHL), the lubricant is subjected to enormous pressures, there is considerable local heating, and the assumption of constant viscosity no longer holds up. The derivation of the governing equations for elastohydrodynamic lubrication, the pressure and temperature dependence of viscosity is recognized after the lubrication thin film approximation has been made. The viscosity of the nanooils consistently exceeded that of the paraffin oil enlarging the partial EHL area with a complete lubricating film between two move iron surfaces. The spherical geometry of TiO2 nanoparticles caused them to act as a rolling medium when the machine parts move which is in the solid friction area. Because they provide a rolling function, spherical titanium oxide nanoparticles have feasible tribological and lubrication applications in the mechanical industry to reduce noise, vibration and friction wear.     

工业纯钛TA1的高温摩擦与磨损行为

工业纯钛(TA1)表面塑性剪切抗力较低且氧化膜保护作用有限,在滑动摩擦时会产生严重的磨损行为。经高温氧化处理的TA1圆盘试样通过高温摩擦磨损试验机以及扫描电镜(SEM)和能谱(EDS)分析,研究实验温度、氧化膜及富氧α层对TA1摩擦磨损行为的影响规律。结果表明,由于磨屑的润滑作用,在相同的载荷和磨损时间下,有氧化层TA1的摩擦因数范围在0.07~0.3,无氧化层TA1摩擦因数范围在0.55~0.9之间。摩擦磨损实验温度越高,有氧化层的TA1摩擦处的犁沟形貌分布越多、越深。对于无氧化层TA1试样,随温度升高和对磨时间的延长,裂纹更易扩展形成剥层磨损。TA1材料的主要磨损方式为剥层磨损、黏着磨损以及氧化磨损,无氧化膜及富氧α层的TA1材料黏着磨损更为严重。表面硬度和磨损机制不同造成高温下摩擦磨损性能的差异。     

Nano-porous layer on steel surface as lubricant carrier

In cold forging of steels, metal soap on zinc-phosphate coating is excellent lubrication system. However, the system is not only less productive, but produces hazardous wastes. In this study, an alternative lubrication system using surface porous layer is proposed. Surface oxide on low carbon steel turns into porous layer by chemical reduction using hydrogen. It is found that liquid lubricant decreases the friction coefficient in compression greatly. The porous surface enhances the decrease, especially in the cases of heavy deformation.     

VN-Ag-MoO3复合材料的制备及宽温域摩擦学行为

利用真空热压烧结技术制备了VN-Ag-MoO₃复合材料,研究了Ag₂MoO₄对VN基复合材料组织结构及宽温域摩擦磨损性能的影响。结果表明:VN-Ag-MoO₃复合材料组织较致密,主要由VN、MoO₃和Ag组成,其中均匀分布于VN基体的MoO₃和Ag由Ag₂MoO₄经高温分解形成。宽温域摩擦磨损测试表明,Ag₂MoO₄的添加有效改善了室温(RT)~700℃温域范围VN陶瓷的摩擦磨损性能。其中,700℃时Ag₂MoO₄含量为10wt%的VN-10Ag-MoO₃的摩擦系数(0.285)和磨损率(1.37×10?5 mm3/(N·m))分别较VN降低了23%和72%,这归因于磨损表面的氧化钒、钒酸银和钼酸银等高温润滑相起到了优异的润滑及减磨作用。      

Preparation and tribological performance of chemically-modified reduced graphene oxide/polyacrylonitrile composites

Interface control and dispersion of graphene base nanomaterials in polymer matrix are challenging to develop high comprehensive nanocomposites due to their strong interlayer cohesive energy and chemical inertia. In this research, an efficient approach is presented to functionalize reduced graphene oxide nanosheets by N-[3-(trimethoxylsilyl)propyl]ethylenediamine, which is dispersed into polyacrylonitrile to prepare N-[3-(trimethoxylsilyl)propyl]ethylenediamine – reduced graphene oxide/polyacrylonitrile nanocomposites. A thermogravimetric analysis technique was employed to evaluate thermal properties of the nanocomposites. The tribological properties of the polyacrylonitrile/graphene nanocomposites were investigated. The morphologies and volume of the worn surface were examined using a 3D profilometer. The impact of loading ratio on friction coefficient, carry-bearing capacity and durability were studied. The N-[3-(trimethoxylsilyl)propyl]ethylenediamine – reduced graphene oxide/polyacrylonitrile nanocomposite with appropriate loading ratio of reduced graphene oxide exhibited a high load-bearing capacity and durability. Therefore, the polyacrylonitrile/graphene nanocomposite shows promising potential to industrial applications involving the lubrication and anti-wear.     

Performance of truncated surface asperities in elastohydrodynamic lubrication

The elastohydrodynamic lubrication in a sliding line contact between a flattened rough plane surface and a smooth plane surface is analytically studied. Both surfaces are assumed as elastic and parallel to one another. The flattened rough surface is treated as equivalent to a rough plane surface with uniformly distributed cylindrical asperities evenly truncated on the top. For understanding the elastohydrodynamic lubrication performance between these two plane surfaces, an inlet zone analysis is taken for the elastohydrodynamic lubrication formed between a truncated cylindrical asperity and the smooth plane surface. It is found from the obtained results that the asperity truncation reduces the elastohydrodynamic load-carrying capacity, and this effect is significant for low sliding speeds or/and heavy loads, while it is negligible for high sliding speeds and moderate loads. The asperity truncation increases the friction coefficient of the asperity contact especially at relatively light loads, while it only slightly increases the friction coefficient of the asperity contact at heavy loads. For heavy loads, the asperity truncation can have a significant effect on the reduction in the maximum surface temperature rise. It is recommended by the present study that the surface asperity be truncated in a certain degree in an elastohydrodynamic contact with high sliding speeds and relatively heavy loads because of giving the benefits of considerably reducing the maximum surface temperature rise while maintaining the elastohydrodynamic load-carrying capacity.     

PTFE微粉/CF改性PEEK复合材料的摩擦磨损性能

为解决核电水循环系统中鼓型旋转滤网驱动装置的耐腐蚀问题,本文研究了碳纤维和聚四氟乙烯微粉改性的聚醚醚酮复合材料在干摩擦、水润滑和油润滑条件下的摩擦磨损性能.通过机械共混、高温模压的方法,制备了不同质量分数的聚四氟乙烯(PTFE)微粉/碳纤维(CF)/二硫化钼(MoS_2)/聚醚醚酮(PEEK)复合材料.采用拉伸试验机和塑料洛氏硬度计测试其力学性能,采用摩擦磨损试验机测试了复合材料在干摩擦、水润滑和油润滑条件下的摩擦磨损性能,采用扫描电子显微镜对其摩擦表面形貌进行分析.结果表明:复合材料在水润滑和油润滑时摩擦系数及磨痕宽度均较小,但水润滑时摩擦系数波动幅度较大且磨痕宽度略高;复合材料在干摩擦条件下的磨损机制以磨粒磨损为主,伴有疲劳磨损,油润滑时摩擦面可形成连续的润滑膜而保持光滑,水润滑时水流冲刷破坏了摩擦面上固体润滑膜的稳定性;CF质量分数增加时,复合材料的洛氏硬度和压缩强度递增,压缩强度达到164 MPa,PTFE微粉质量分数增加时,复合材料的洛氏硬度和压缩强度递减;CF质量分数增加时,复合材料的干摩擦系数及磨痕宽度下降,PTFE微粉质量分数增加时,复合材料的干摩擦系数下降,达到0.17.     

Lubrication characteristics of nano-oil with different degrees of surface hardness of sliding members

In this study, the lubrication characteristics of sliding members were compared with the changes in the hardness of friction surfaces and the application of nano-oil. The materials of the specimens were gray cast iron (AISI 35 and AISI 60) and nickel chromium molybdenum steel (AISI 4320). The friction coefficients and the temperature variations of the frictional surfaces were measured with a disk-on-disk tribotester under a fixed rotation speed. The friction surfaces were observed with a scanning electron microscope (SEM). The friction coefficients of the plate surface increased as the hardness difference increased. The friction coefficient after the lubrication with nano-oil was less than that after lubrication with mineral oil. This is because a spherical nanoparticle plays the role of a tiny ball bearing between the frictional surfaces that improve the lubrication characteristics.     

Microstructure and Tribological Properties of Plasma-sprayed Nanostructured Sulfide Coating

The friction and wear properties of plasma-sprayed nanostructured FeS coating were investigated on an MHK- 500 friction and wear tester under both oil lubrication and dry friction condition. The microstructure, worn surface morphology and phase composition of the coating were characterized by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. It was found that the coating was mainly composed of FeS. a small quantity of Fe1-xS and oxide were also found. The coating was formed by small particles of 50～100 nm in size The thickness of the coating is approximately 150 μm. The friction-reduction and wear-resistance properties of plasma-sprayed nanostructured FeS coating were superior to that of GCr15 steel substrate. Especially under oil lubrication condition, the friction coefficient of nanostructured FeS coating was 50% of that of GCr15 steel, the wear scar widths of the coating were also reduced to nearly 50% of that of GCr15 steel under high load. The failure of the coating was mainly attributed to plastic deformation under both oil lubrication and dry friction condition.     

Development of a novel cooling system-assisted minimum quantity lubrication method for improvement of milling performance

This paper presents a novel lubrication method for milling processes that employs cooling system-assisted minimum quantity lubrication (CSMQL) using a thermoelectric cooling system. The CSMQL method improves the cooling effect in the cutting area and enhances processing quality, in addition to reducing energy consumption. Four different coolant strategies including CSMQL, dry, minimum quantity lubrication (MQL), and wet methods were compared in processing mill die steel (SKD11), which is widely used in industry. Different aspects of the milling performance (e.g. surface roughness, morphology, milling temperature, and milling forces) were investigated using these coolant strategies. The experimental results show that not only is the surface roughness of steel milled using CSMQL better than that of steel milled using dry and MQL methods, but CSMQL also produces fewer tool marks on the workpiece surface. In addition, it was found from observations of chip color that using the CSMQL method reduced the cutting temperature by 27% and the cutting force by 22%, compared with dry machining. In summary, the use of CSMQL can not only improve the surface roughness and reduce the cutting force and cutting temperature, but also promote processing quality. This study will help researchers develop more efficient cooling strategies in the future.     

直线运动滚动导轨副混合润滑研究

综合考虑了直线运动导轨副接触几何、预紧力、真实表面粗糙度、曲率系数等因素,建立了直线运动导轨副混合润滑数值模型,研究了滑块移动速度、曲率半径系数、工作载荷、表面粗糙度对导轨接触副润滑特性的影响,得到结论:导轨副法向工作载荷、最大赫兹接触压力和赫兹接触半径随着外加总载荷的增大而增大,平均膜厚随着载荷的增大而减小;混合润滑模型可预测导轨副在大范围工况条件下完整的润滑状态;直线运动导轨大多工作在混合润滑状态下,随着滑块移动速度的增加,接触界面由边界润滑状态向混合润滑状态转变,润滑性能逐渐提高;适当增加曲率半径系数,有利于润滑油膜的形成与稳定。     

MoS_2氧化表面的角度分辨X射线光电子谱研究

利用角度分辨X射线光电子谱方法（AXPS）研究MoS2固体润滑材料氧化表面的化学状态，同时，用电子自旋共振（ESR）法发现氧化物存在未成对电子Mo5 ，因而氧化物存在Mo原子的三种化学状态，形成了单电子的传递、转移。MoS2的表面数分子层内的Mo原子氧化程度有差异，这种非破坏性的剖面分析方法有助于深入了解MoS2的氧化行为。     

Wear behavior of light-weight and high strength Fe-Mn-Ni-Al matrix self-lubricating steels

The good combination of mechanical and tribological properties for self-lubricating materials is crucial. In this work, novel self-lubricating Fe-16.4 Mn-4.8 Ni-9.9 Al-xC(wt%) steels containing graphite phase were fabricated using mechanical alloying and spark plasma sintering. The compositions of the steels were designed by using thermodynamic calculation, and the effect of carbon addition on the microstructure was further investigated. The steel possesses high hardness of 621 HV, high yield strength of 1437 MPa and good fracture toughness at room temperature. The yield strengths are still above 600 MPa at 600?C.The tribological behavior and mechanical properties from room temperature to 800?C were studied, and the wear mechanisms at elevated temperatures were discussed. The steel has a stable friction coefficient of 0.4 and wear rate in a magnitude of 10~(-6) mm~3/N·m below 600?C. The good tribological properties of the steels were mainly attributed to the high hardness, lubrication of graphite and stable surface oxide layer.     

油酸修饰纳米BN/TiN润滑添加剂的摩擦学性能研究EI北大核心CSCD

使用油酸对BN,TiN,BN/TiN纳米添加剂进行表面改性修饰,通过傅里叶红外光谱仪进行表征,利用四球摩擦磨损试验机考察润滑油纳米添加剂的摩擦学性能。结果表明:油酸成功枝接在纳米颗粒表面,提高其分散性能。与纯基础油相比,纳米添加剂工况摩擦因数降低11.7%,磨斑直径降低29.5%,磨斑表面未出现起皮脱落现象,沟槽深度、宽度明显降低,混合BN/TiN纳米添加剂表现出协同润滑作用。纳米BN,TiN颗粒能够进入摩擦副中,起到微轴承作用,降低摩擦磨损,进入摩擦副中的纳米BN与摩擦副基体材料发生化学反应,生成氮化硼、氧化硼、氧化铁等物质修复磨损表面。     

Influence of Lubrication Performance on the Service Life of Rolling Mill Bearings

In order to confirm the early failure cause of a four-row cylindrical roller bearing at the backup roll position of a six-high cold sheet mill, its lubrication behavior under harsh operating conditions is investigated. Through establishing and solving the Elastohydrodynamic Lubrication （EHL） model of the roller-inner raceway contact region, the minimum oil film thickness and the real lubrication performance are achieved. The results show the bearing failures come from the poor oil film thickness in the case of high temperature and low rotational speed, which leads to contact wear. So various approaches to improve bearing life via improving lubrication are compared. It has been proved decreasing surface roughness of both contact bodies is an effective way.     

Modeling of Microimprinting of Bulk Metallic Glasses

A finite element analysis （FEA） model has been developed to analyze microimprinting of bulk metallic glasses （BMG） near the glass transition temperature （Tg）. The results reveal an approximately universal imprinting response for BMG, independent of surface feature length scale. The scale-independent nature of BMG imprinting derives from the flow characteristics of BMG in the temperature range above Tg. It also shows that the lubrication condition has a mild influence on BMG imprinting in the temperature range above Tg.     

备用轴承碰撞副对电磁轴承失效后转子坠落瞬态响应的影响

在一个电磁轴承支撑的柔性转子实验系统上测量了电磁轴承失效后转子坠落在不同碰撞副滚动型备用轴承上的瞬态响应,分析了碰撞副的材料和润滑条件对转子坠落过程中瞬态响应的影响。结果发现碰撞副材料的不同配合和碰撞副间的润滑条件对转子坠落在备用轴承上的瞬态响应有明显的影响。适当地选择碰撞副材料以及保持碰撞副间良好的润滑有利于减小转子坠落过程对备用轴承和转子的影响,特别是能够避免出现对备用轴承有显著影响在整个间隙圆范围的碰撞型回转运动,提高备用轴承的抗冲击能力。     

Finite element analysis of microimprinting of bulk metallic glasses in supercooled liquid regime

A finite element analysis (FEA) model to analyze imprint of a bulk metallic glass (BMG) in the temperature range near the glass transition temperature (T _g) has been developed. The material model includes both Newtonian and non-Newtonian flow behavior. The results reveal that the topology of the imprinted surface depends strongly on temperatures, but only mildly on surface feature scale. As a result of the flow characteristics of BMG in the temperature range above T _g, the lubrication condition has only a slight effect on BMG imprinting.     

铜箔轧制润滑状态与表面质量的研究

使用不同运动粘度的轧制油和在不同道次压下率条件下进行了铜箔冷轧实验。利用激光扫描共焦显微镜(LSCM)和表面粗糙度仪对铜箔轧后表面形貌进行了表征,得到铜箔轧制变形区膜厚比和摩擦系数。研究了轧制油运动粘度,道次压下率对铜箔轧制变形区油膜厚度、表面粗糙度和前滑值的影响,并从膜厚比、摩擦系数和表面质量3个方面对不同润滑条件下铜箔轧制变形区的润滑状态进行了界定。结果表明,轧制油运动粘度γ40≤15mm2/s时,膜厚比λ→0,摩擦系数μ≈0.1～0.2,属于边界润滑状态,表面质量较好;道次压下率20%<ε≤60%时,膜厚比λ→0,摩擦系数μ>0.1,属于边界润滑状态,表面质量较好。为得到高表面质量的铜箔,轧制油运动粘度应控制在10mm2/s左右,道次压下率控制在30%左右,也即,使铜箔轧制润滑状态控制在边界润滑状态为最佳。