Influence of the Wetting Properties of Liquids on the Tribological Behavior of Selected Sliding Materials in Mechanical Seals

Theoretical investigations are carried out for a plain journal bearing considering the influence of thermal effects on non-Newtonian lubrication. With reasonable assumptions, the steady state and dynamic characteristics are presented using a thermohydrodynamic analysis of a bearing lubricated by a nonlinear, i.e., cubic, fluid model.

Experiments are conducted on a rig to study the steady state and dynamic performance of a full journal bearing with different types of non-Newtonian lubricants. Experiments include the measurements of eccentricity ratio, critical speed, and stability limit.

The theoretical investigation reveals that the interaction of the non-Newtonian effect and the thermohydrodynamic effect is strong for friction, and the interaction effect is negligible in the case of eccentricity ratio, attitude angle, and lubricant flow rate. Further, for relatively high values of non-Newtonian parameter, α_n , the effect due to the non-Newtonian parameter is not negligible.     

铝-硅合金表面激光合金化处理

在一定的激光工艺参数下，对ZL108合金含SiO2和硅的涂层进行处理，其合金化组织细化．且出现过共晶组织。含钛 碳 铝涂层经激光处理后，存在TiC和Ti颗粒，提高了合金化层的硬度，明显改善了其摩擦磨损性能。     

几种纳米润滑剂的摩擦学特性

采用超速粉碎工艺结合抗凝聚技术研制了三种不溶于水的纳米润滑添加剂：二硫化钼（MoS2）、聚四氟乙烯（PTFE）和滑石粉（talcum）。配方侧重考察了这些纳米级固体润滑剂的摩擦学特性，尤其是针对铜－钢摩擦副的摩擦磨损特性。结果发现在铜－钢摩擦副条件下，纳米级PTFE及滑石粉具有较好的抗铜磨损和降低摩擦系数的减摩性能；含硫的添加剂（包括MoS2）反而对铜引起不良摩擦的润滑作用。     

聚合物合金的摩擦磨损特性的研究

作者采用了聚合物共混技术研制了ＰＣ＋ＰＴＦＥ，ＰＣ＋ＰＴＦＥ＋ＰＰＳ两类聚合物合金，并对这些材料的摩擦学特性及其机理进行了研究。结果表明，ＰＴＦＥ的添加不仅可以提高ＰＣ的耐磨性，而且还可降低其摩擦系数；适量的ＰＰＳ的添加具有减摩抗磨作用。聚全物及其合金的摩擦特性可由粘着摩擦理论解释，其磨损过程主要受粘着，磨粒和疲劳机理控制。     

Experimental Investigation of Partial Laser Surface Texturing for Piston-Ring Friction Reduction

An experimental study is presented to evaluate the effect of partial laser surface texturing (LST) on friction reduction in piston rings. In a previous study, 30% friction reduction was obtained with full LST where the full width of the piston ring is textured with a very large number of microdimples that act individually as microhydrodynamic bearings. In partial LST, only a portion of the piston-ring width is textured with high dimple density, producing a “collective” effect of the dimples that provides an equivalent converging clearance even with nominally parallel mating surfaces. Experimental results obtained with flat and parallel test specimens with partial LST are presented, confirming a previously published theoretical model and the advantage of partial over full LST. Friction reduction by LST with actual production-crowned piston rings and cylinder liner segments is not straightforward and needs further investigation.     

SPN型添加剂对岩石／钢摩擦副摩擦学性能的影响

本文考察了含ＳＰＮ型添加剂的乳化液型水基润滑剂对４５钢－石灰岩摩擦副的摩擦学性能的影响。在销盘实验机进行的摩擦学实验显示这种添加剂有一定的减摩抗磨作用,用扫描电子显微镜（ＳＥＭ）和Ｘ射线光电能谱（ＸＰＳ）对摩擦副进行表面分析表明有硫磷氮等化合物的形成。     

拉深模激光毛化表面的磨损性能研究

为提高拉深模的磨损性能和使用寿命,利用激光毛化技术在模具钢试样表面分别加工出不同直径和间距的微单元体。对比研究毛化表面试样和非毛化表面试样的磨损性能,结果表明,毛化试样表面耐磨性均优于非毛化表面试样。通过激光毛化可提高拉深模寿命,改善板料成形时的流动性。     

再探纳米金刚石对缸套表面摩擦学改性机理

爆炸法人工合成的纳米金刚石粉,是一种具有实用价值的新兴纳米材料,它具有一系列特殊的物理和化学特性。本针对车用内燃机缸套一活塞环摩擦副磨合期工作特点,利用超精细纳米金刚石的特殊性能,对其进行摩擦学改性机理分析。     

环己氧基硼酸镧的摩擦学性能研究

以硼砂为原料合成了环己氧基硼酸镧,采用ＭＳ－８００Ａ摩擦试验机和ＨＱ－１摩擦磨损试验机研究了其抗磨减摩性,并采用Ｘ－射线光电子能谱仪（ＸＰＳ）分析了磨斑表面膜表面组成和价态。实验结果表明,环己氧基硼酸镧具有良好的抗磨减磨性。其作用机理可能是环己氧基硼酸镧在摩擦过程上分解为三氧化二和三氧化二硼等反应物膜,从而起到了抗磨减摩作用。     

The Effect of Laser Texturing of Steel Surfaces and Speed-Load Parameters on the Transition of Lubrication Regime from Boundary to Hydrodynamic

Laser surface texturing (LST) is an emerging, effective method for improving the tribological performance of friction units lubricated with oil. In LST technology, a pulsating laser beam is used to create thousands of arranged microdimples on a surface by a material ablation process. These dimples generate hydrodynamic pressure between oil-lubricated parallel sliding surfaces. The impact of LST on lubricating-regime transitions was investigated in this study. Tribological experiments were carried out on pin-on-disk test apparatus at sliding speeds that ranged from 0.15 to 0.75 m/s and nominal contact pressures that ranged from 0.16 to 1.6 MPa. Two types of oil with different viscosities (54.8 cSt and 124.7 cSt at 40°C) were evaluated as lubricants. Electrical resistance between flat-pin and laser-textured disks was used to determine the operating lubrication regime. The test results showed that laser texturing expanded the range of speed-load parameters for hydrodynamic lubrication. LST also reduced the measured friction coefficients of contacts that operated under the hydrodynamic regime. The beneficial effects of laser surface texturing are more pronounced at higher speeds and loads and with higher viscosity oil.     

Wear Behavior of Al-Si Alloy Impregnated Graphite Composite

Pin-on-disk type unidirectional sliding wear experiments for an Al-Si alloy impregnated graphite composite (pin) in contact with a bearing steel (disk) were conducted at various contact loads in wet and dry air to investigate the wear behaviors in detail. The pin-lifting phenomena of the composite as observed. The height was constant at lower loads and increased with load. The entrance of wear particles into the contacting surfaces brought about the pin lifting. Mixtures of graphite powder and wear particles adhered to the sliding surface of the bearing steel, resulting in the formation of wide, compacted surface films. The mean thickness of the films increased with load to a few micrometers. The composite exhibited better wear resistance than the matrices in wet air and the wear rate decreased especially at high loads. The wide, compacted films together with the pin-lifting phenomena prevent metal-to-metal contact, achieving a good anti-wear condition. On the other hand, the surface films that adhere in a scaled fashion in dry air have little wear reduction effect.     

The Tribological Properties of Oils Added with Diamond Nano-Particles

A technique of relative optical interference intensity (ROII) and a high-precision force measuring system were used to measure film thickness and friction force of the oils added with ultra-fine diamond powder (UDP) in the nano-scale. The results show that the oil containing UDP nano-particles forms a thicker film than does the pure base oil. In the rubbing process, the hard spherical UDP nano-particles plow the two surfaces and produce many smooth micro-grooves. The friction force decreases with sliding distance. The possible mechanisms for such reduction and physical model of diamond nano-particles as additives in oils are discussed.     

激光毛化自润滑耐磨减振金属橡塑缓冲条复合成形技术研究

国内现有缓冲条产品在耐磨、抗冲击、粘结强度、密封性等方面还无法较好地满足输送机械的应用需求,激光毛化技术的发展使制备寿命长、性能好的缓冲条成为可能。从缓冲条金属骨架表面处理技术、缓冲条金属骨架与橡塑热硫化粘结技术两方面对激光毛化自润滑耐磨减振金属橡塑缓冲条复合成形技术进行了研究,对缓冲条表面自润滑超高分子量聚乙烯材料进行了介绍,并对缓冲条复合成形技术的未来发展进行了展望。     

硼化二正丁基二硫代氨基甲酸酯的摩擦学性能研究

合成了硼化二正丁基二硫代氨基甲酸酯的采用四球实验机和ＨＱ－１摩擦磨损实验机研究了其抗磨减摩性能,并采用Ｘ－射线光电子能谱仪（ＸＰＳ）分析了磨斑表面组成和元素价态。实验结果表明：硼化二正丁基二硫代氨基甲本 良好的抗磨减摩性能和承载能力,其作用机理可能是添加剂在摩擦过程中与金属表面作用,形成含有机硼、有机氮、ＦｅＳ２和ＦｅＳｏ４的复合膜,从而起到抗磨减摩作用。     

活塞环表面离子镀硬质膜的摩擦学性能研究

为了改善发动机活塞环的摩擦学性能和提高其使用寿命,采用离子镀技术在活塞环表面制备了CrN硬质膜,并利用SRV摩擦磨损试验机考察了硬质膜的摩擦学特性,研究结果表明离子镀硬质膜的摩擦系数基本与镀铬层一致,但磨损量远低于镀铬层的磨损量,与两种涂层活塞环配副的缸套试样的磨损量基本相当。     

山高刀具助力首都航天机械公司高精高效生产

<正>未来的某一天,我们将会看到这样的景象:来自世界任何一个角落的用户都能享受到由中国的卫星导航系统所提供的定位、导航、授时服务。事实上,这个"未来"并不遥远,我国的第二代卫星导航系统——北斗卫星导航系统将在2020年之前把这个美丽的设想变成现实。     

Improving Tribological Performance of Mechanical Components by Laser Surface Texturing

Significant improvement in load capacity, wear resistance, friction coefficient etc. of tribological mechanical components can be obtained by forming regular micro-surface structure in the form of micro-dimples on their surfaces. A feasibility study was performed both theoretically and experimentally using the Laser Surface Texturing (LST) technique to produce the micro-dimples. Each micro-dimple can serve either as a micro-hydrodynamic bearing in cases of full or mixed lubrication or as a micro-reservoir for lubricant in cases of starved lubrication conditions. Theoretical models were developed, and laboratory tests were performed, to investigate the potential of LST in tribological components like mechanical seals, piston rings and thrust bearings. In the entire laboratory tests, friction was substantially reduced with LST compared to the non-textured components.     

Theory of Life Prediction of a Viscoelastic Lubricating Surface Film

A solid lubricating surface film is modeled as a general linear viscoelastic material. The appropriate governing equations are solved for the displacement of such a thin film under repeated loadings. The predicted transient motion of the surface is monitored. The gradual diminution of the lubricant film thickness under repeated loadings is considered film wear. The failure of solid lubricating film occurs when the existing thickness is to the same order of magnitude as the substrate surface roughness.     

The Structural and Tribological Properties of MoS2-Ti Composite Solid Lubricants

MoS ₂ -Ti composite solid lubricant films were deposited on an AISI D2 tool steel and silicon wafer by CFUBMS (closed field unbalanced magnetron sputtering). The deposition process was performed for nine different test conditions at various levels of target current, working pressure, and substrate voltage using the Taguchi L ₉ (3 ⁴ ) experimental method. It was observed that the chemical composition of MoS ₂ -Ti composite films was significantly affected by sputtering parameters. It was determined that the microstructure of composite films is neither crystalline nor amorphous; in other words, it is quasi-amorphous, and (002) and (100) planes characteristic of MoS ₂ occurred. The friction coefficients of the films were determined over 1800 s and at a loading of 10 N by means of a pin-on-disk tribotester. The changes in friction coefficient were related to structural changes based on Ti addition and the different levels of deposition parameters.     

激光表面合金化裂纹的研究

对铸铁进行了大量的激光表面合金化试验研究 ,找出了工艺参数、基材类型、试样的几何尺寸和合金粉末种类对激光表面合金化裂纹率的影响规律