稀土氧化物或合金化元素对Ni－Cr－5S合金物理机械性能和摩擦学性能的影响

虽然含硫量为５％（ｗｔ）的Ｎｉ－Ｃｒ－５Ｓ合金的自润滑性能比较好，但由于这种合金中存在着多种ＣｒｘＳｙ型化合物夹杂，故其机械强度受到影响而难以满足实际工况对材料之机械性能和摩擦学性能都比较好的双重要求。为了探求进一步提高Ｎｉ－Ｃｒ－５Ｓ合金综合性能的有效方法，考察了稀土氧化物ＣｅＯ＿２和Ｌａ＿２Ｏ＿３，以及合金化元素铁、钼、铌、钴等对这种合金之物理机械性能和摩擦学性能的影响．结果表明，添加适量的稀土氧化物或合金化元素能够改变Ｎｉ－Ｃｒ－５Ｓ合金的组织结构与组成而使其综合性能得以改善。在此基础上，又研制出一种实用性比较强的九组元ＰＢ合金，其在大气中从室温至６００℃的温度范围内都具有比较高的机械强度和良好的摩擦磨损性能，是一种可以在高温、高速和高负荷条件下使用的自润滑材料。     

稀土氧化物或合金化元素对Ni—Cr—5S合金物理机械性能和摩擦学性…

虽然含硫量为５％的Ｎｉ－Ｃｒ－５Ｓ合金的润滑性能比较好，但由于这种合金中存在着多种ＣｒｘＳｙ型化合物夹杂，故其机械强度受到影响而难以满足实际工况对材料性能和摩擦学性能都比较学的双重要求，为了探求进一步提高Ｎｉ－Ｃｒ－５Ｓ合金综合性能的有效方法，考察了稀土氧化物ＣｅＯ２和Ｌａ２Ｏ３，以及合金化元素铁，钼，铌，钴等以地这种合金之物理机械性能和摩擦学性能成而使其综合性能得以改善，在此基础上，又研制出一种     

Ni—Cr—Ml—Al—Ti—B—MoS2系合金高温摩擦学特性的研究

用粉末冶金法制备了Ｎｉ－Ｃｒ－Ｍｏ－Ａｌ－Ｔｉ－Ｂ－ＭｏＳ２系宽温度范围自澜残杀则试了合金机械性能及其在室温６００℃范围内的摩擦磨损性能,同时还了其耐磨机理。研究结果表明,ＭｏＳ２质量分数为１０％的合金具有较好的机械和摩擦磨损综合性能。该合金主要由Ｎｉ基固溶体、Ｎｉ３Ａｌ、Ｎｉ３（Ａｌ,Ｔｉ）、不定比化合物ＣｒｘＳｙ、ＭｏＳ２和Ｍｏ２Ｓ３等相组成,在室温至３００℃范围内摩擦表面形成含硫化合物复合膜     

Ni-Cr-Mo-Al-Ti-B-MoS2系合金高温摩擦学特性的研究

用粉末冶金法制备了Ｎｉ－Ｃｒ－Ｍｏ－Ａｌ－Ｔｉ－Ｂ－ＭｏＳ２系宽温度范围自润滑合金材料,测试了合金机械性能及其在室温至６００ ℃范围内的摩擦磨损性能,同时还探讨了其耐磨机理．研究结果表明,ＭｏＳ２ 质量分数为１０％ 的合金具有较好的机械和摩擦磨损综合性能．该合金主要由Ｎｉ基固溶体、Ｎｉ３Ａｌ、Ｎｉ３（Ａｌ,Ｔｉ）、不定比化合物ＣｒｘＳｙ、ＭｏＳ２ 和Ｍｏ２Ｓ３ 等相组成,在室温至３００ ℃范围内摩擦表面形成含硫化合物复合膜而起润滑作用,高温摩擦时承载表面形成釉质层,次表层形成氧化层,其硬度比合金基体高,这是合金具有良好高温耐磨性的基础．高温下摩擦表面及磨屑中的氧化物及残余硫化物的协同作用使摩擦系数进一步降低．     

含硫镍合金的研制及其高温摩擦学特性

采用粉末冶金工艺和中频励磁感应加热高温快速热压成型法，研制出几种含硫和不含硫的镍合金高温自润滑耐磨材料，进而从中筛选出一种在室温和３００℃乃至６００℃都具有较高机械强度和低摩擦、耐磨损的含活性元素Ｓ的多元镍合金．对这种合金在较高速度和较高负荷条件下的摩擦学性能进行了试验研究，并且利用Ｘ射线衍射仪、Ｘ射线光电子能谱仪和Ｘ射线能量色散谱仪等揭示了这种合金的自润滑机理．结果表明：这种含硫镍合金在室温和３００℃下与ＷＣ－Ｎｉ－Ｃｏ－Ｍｏ－ＰｂＯ金属陶瓷对摩时，起润滑作用的主要是ＭｏＳ２和元素Ｃｒ与Ｓ的不定比化合物所形成的复合膜；在５００～６００℃的高温摩擦过程中，起润滑作用的主要是由不定比化合物ＣｒｘＳｙ与偶件转移物ＰｂＷＯ４及ＭｏＯ３和ＮｉＯ组成的复合膜     

四种陶瓷材料与SUS304不锈钢的高温摩擦学特性研究

为了探索陶瓷与金属组合作为高温润滑材料的可能性，利用端面摩擦磨损试验机测定了４种陶瓷ＳｉＣ、Ｓｉ３Ｎ４、Ａｌ２Ｏ３和ＺｒＯ２与ＳＵＳ３０４不锈钢在室温至５００℃下的摩擦学性能．摩擦试验结果表明，ＳｉＣ、Ｓｉ３Ｎ４和Ａｌ２Ｏ３在低于２００℃时的摩擦系数稳定且都低于０．２，但在２００℃以上时的摩擦性能却都不稳定，摩擦系数在０．２－０．４之间；ＺｒＯ２在２００℃以下时的摩擦性能不稳定，而在２００℃以上时的摩擦系数低于６．２且较稳定。磨损试验结果表明，在４种陶瓷中ＺｒＯ２的磨损率最低［－２．６０×１０－９ｍｍ３／（Ｎ·ｍ）］，ＳｉＣ和Ｓｉ３Ｎ４的磨损率居中［分别为１．８０×１０－６ｍｍ３／（Ｎ·ｍ）和４．４０×１０－６ｍｍ３／（Ｎ·ｍ）］，Ａｌ２Ｏ３的磨损率最高［３．６４×１０－５ｍｍ３／（Ｎ·ｍ）］；分别与这４种陶瓷对磨的不锈钢的磨损率都高［１．４０×１０－５－４．５２×１０－５ｍｍ３／（Ｎ·ｍ）］．     

Fe—Ni—P合金镀层与几种材料配副在边界润滑下的摩擦学特性

研究了Ｆｅ－Ｎｉ－Ｐ合金镀层与４５＃钢，ＧＣｒ１５轴承钢，ＱＳｎ６．５－０．４磷锡青铜，１Ｃｒ１８Ｎｉ９Ｔｉ不锈钢，Ｃｒ猎层或Ｎｉ－Ｐ镀层分别组成摩擦副时在边界润滑下的摩擦磨损性能。结果表明：在给定的试验条件下，Ｆｅ－Ｎｉ－Ｐ合金镀层与１Ｃｒ１８Ｎｉ９Ｔｉ奥氏体不锈钢组成摩擦副对摩 时容易产生粘着，磨损量和摩擦因数都比较高，而且配副材料的抗擦伤临界载荷也很低，以Ｆｅ－Ｎｉ－Ｐ合金镀层分别以其它５种     

新型Ni－Fe－W－S合金刷镀层耐磨性的研究

镀铬是用于提高材料常温耐磨性的有效方法。但是，铬镀层在摩擦温升的作用下，其硬度和耐磨性却都下降，而且镀铬还会污染环境和对人体造成损害．为了克服铬镀层和镀铬工艺的这些缺点，研究了一种新型的Ｎｉ－Ｆｅ－Ｗ－Ｓ合金刷镀层，摩擦磨损试验结果表明，在于摩擦时于高速（７１ｍ／ｍｉｎ）和重载（８０Ｎ）条件下，这种合金刷镀层的耐磨性能明显地比铬镀层的好，磨痕形貌的扫描电子显微镜观察发现，前者发生的是应变疲劳磨损，而后者已经发生了严重的粘着磨损．同时，通过对高速重载干摩擦条件下平均温度和闪温的计算，并且利用Ｘ射线衍射仪和透射电子显微镜等对磨损前后镀层的相结构及显微组织的分析，探讨了Ｎｉ－Ｆｅ－Ｗ－Ｓ合金刷镀层在如此苛刻条件下具有较高硬度和良好耐磨性能的机理，指出这是在摩擦热的作用下合金刷镀层中部分非晶向晶态转化前发生微观结构畸变并形成了更多硬质相的结果．     

WC－Ni－Mo－PbO高温自润滑金属陶瓷材料的研制及其综合性能考察

针对某热动力机械之动密封摩擦偶件用材的需要，以ＷＣ－Ｎｉ－ＰｂＯ材料为基料，通过陶瓷相ＷＣ的微细化和金属Ｍｏ的加入，利用中频感应加热的热压法研制出一种在高温下具有机械强度高、摩擦系数低和耐磨性能好等优点的ＷＣ－Ｎｉ－Ｍｏ－ＰｂＯ高温自润滑金属陶瓷材料，并且通过Ｘ射线衍射仪、电子探针微区分析仪和多功能电子能谱仪等近代分析手段揭示了这种材料的高温自润滑机理，研究结果表明，摩擦表面ＰｂＷＯ＿４润滑膜的形成是ＷＣ－Ｎｉ－Ｍｏ－ＰｂＯ金属陶瓷材料在高温下具有良好自润滑性能的主要原因。利用这种材料制作成某热动力机械的动密封摩擦偶件已在压力１１．３ＭＰａ、速度３．５ｍ／ｓ、温度１０００－１１００℃的实际工况下成功地运行了４５０秒，并且顺利地连续使用了３次，其各项技术指标均能很好地满足实用要求。     

一种自润滑镍基合金显微组织和相结构分析

为了进一步优化研制的含硫高温自润滑镍基合金的综合性能，以将其应用于新型高效热引擎和推进系统为目的，利用光学显微镜、扫描电子显微镜、电子探针和Ｘ射线衍射仪等，对一种铸态的含硫高温自润滑镍基合金的显微组织和相结构进行了分析．结果表明：这种合金主要由以合金元素Ｆｅ，Ｃｏ，Ｃｒ和Ｍｏ等固溶强化的镍基固溶体基体相、硫化物相Ｃｒ３Ｓ４和复合碳化物相（Ｍｏ０．９Ｃｒ０．１）２Ｃ所组成，具有三元共晶组织特征的显微组织；这种合金的摩擦磨损性能良好，但因Ｃｒ３Ｓ４多呈粗大网状分布，故其强度和冲击韧性都比较差．这为通过调整合金的成分和制备工艺，或采用适当的热处理及后加工工艺改善合金的性能提供了科学依据     

Waves on the surface of a falling power-law fluid film

Waves that occur at the surface of a falling film of thin power-law fluid on a vertical plane are investigated. Using the method of integral relations an evolution equation is derived for two types of waves equation which are possible under long wave approximation. This equation reveals the presence of both kinematic and dynamic wave processes which may either act together or singularly dominate the wave field depending on the order of different parameters. It is shown that, at a small flow rate, kinematic waves dominate the flow field and the energy is acquired from the mean flow during the interaction of the waves, while, for high flow rate, inertial waves dominate and the energy comes from the kinematic waves. It is also found that this exchange of energy between kinematic and inertial waves strongly depends on the power-law index n. Linear stability analysis predicts the contribution of different terms in the wave mechanism. Further, it is found that the surface tension plays a double role: for a kinematic wave process, it exerts dissipative effects so that a finite amplitude case may be established, but for a dynamic wave process it yields dispersion. Further, it is shown that the non-Newtonian character n plays a vital role in controlling the role of the term that contains surface tension in the above processes.     

Simulation and measurement of 3D shear-driven thin liquid film flow in a duct

Three-dimensional flow behavior of thin liquid film that is shear-driven by turbulent air flow in a duct is measured and simulated. Its film thickness and width are reported as a function of air velocity, liquid flow rate, surface tension coefficient, and wall contact angle. The numerical component of this study is aimed at exploring and assessing the suitability of utilizing the FLUENT-CFD code and its existing components, i.e. Volume of Fluid model (VOF) along with selected turbulence model, for simulating the behavior of 3D shear-driven liquid film flow, through a comparison with measured results. The thickness and width of the shear-driven liquid film are measured using an interferometric technique that makes use of the phase shift between the reflections of incident light from the top and bottom surfaces of the thin liquid film. Such measurements are quite challenging due to the dynamic interfacial instabilities that develop in this flow. The results reveal that higher air flow velocity decreases the liquid film thickness but increases its width, while higher liquid flow rate increases both its thickness and width. Simulated results provide good estimates of the measured values, and reveal the need for considering a dynamic rather than a static wall contact angle in the model for improving the comparison with measured values.     

ZDDP作用下钨/钼膜的摩擦化学润滑机理研究

利用SRV高温磨损试验机考察了钨膜、钼膜以及钨-钼合金膜与ZDDP的交互作用规律,并使用XPS和SEM等表面分析技术分析摩擦反应膜的成分与化学态.结果表明:不同材料的薄膜在加入ZDDP后,其表面的摩擦系数的变化趋势与基础油润滑作用下相同,均从0.11降到0.08左右.而磨损量表现出不同的变化规律:钨膜表面的磨损量在加入ZDDP前后均保持在3.7×10-13m3左右;钼膜和钨-钼膜表面的磨损量在加入ZDDP后明显降低,而且钨-钼膜表面的磨损量降低幅度最大,达74.5%.这与不同材料表面的硬度值和生成的表面摩擦反应膜有关.     

类金刚石碳膜的摩擦学特性及其研究进展

从类金刚石碳膜作为耐磨涂层的角度出发,综述了近年来国际上关于类金刚石碳膜摩擦学特性的大量研究,着重讨论了影响类金刚石碳膜摩擦学特性的主要工艺参数和因素,阐明了类金刚石碳膜与金刚石膜在性能上的差异,指出了类金刚石碳膜的发展现状和趋势。     

Stability of conducting liquid flowing down an inclined plane at moderate Reynolds number in the presence of constant electromagnetic field

The stability of a conducting viscous film flowing down an inclined plane at moderate Reynolds number in the presence of electromagnetic field is investigated under induction-free approximation. Using momentum integral method a non-linear evolution equation for the development of the free surface is derived. The linear stability analysis of the evolution equation shows that the magnetic field stabilizes the flow whereas the electric field stabilizes or destabilizes the flow depending on its orientation with the flow. The weakly non-linear study reveals that both the supercritical stability and subcritical instability are possible for this type of thin film flow. The influence of magnetic field on the different zones is very significant, while the impact of electric field is very feeble in comparison.     

Boundary film shear elastic modulus effect in hydrodynamic contact. Part II: influence of operational parameters

The present paper is the subsequent research of the first part (Theor Comput Fluid Dyn, 2009). It investigates the boundary film shear elastic modulus effect in a hydrodynamic contact in different operating conditions. The hydrodynamic contact is one-dimensional, composed of two parallel plane surfaces, which are respectively rough rigid with rectangular micro projections in profile periodically distributed on the surface and ideally smooth rigid. The whole contact consists of cavitated area and hydrodynamic area. The hydrodynamic area consists of many micro Raleigh bearings which are discontinuously and periodically distributed in the contact. The hydrodynamic contact in a micro Raleigh bearing consists of boundary film area and fluid film area which, respectively, occur in the outlet and inlet zones. In boundary film area, the film slips at the upper contact surface due to the limited shear stress capacity of the film–contact interface, while the film does not slip at the lower contact surface due to the shear stress capacity of the film–contact interface large enough. In boundary film area, the viscosity, density, and shear elastic modulus of the film are varied across the film thickness due to the film–contact interactions, and their effective values are used in modeling which depends on the film thickness. In fluid film area, the film does not slip at either of the contact surfaces, and the shear elastic modulus of the film is neglected. It is found from the simulation results that the boundary film shear elastic modulus influences are normally negligible on the mass flow through the contact, the carried load of the contact and the overall film thickness of the contact, and the boundary film shear elastic modulus would normally influence the local film thickness in an elastic contact when the local film thickness is on the film molecule diameter scale. It is also found that the boundary film shear elastic modulus effect has the tendency of being increased with the reduction of the width of a micro contact. It is increased with the reduction of the boundary film–contact interfacial shear strength or with the increase of the critical boundary film thickness, while it is strongest at certain values of the contact surface roughness, the width ratio of fluid film area to boundary film area, and the lubricant film shear elastic modulus.

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Boundary film shear elastic modulus effect in hydrodynamic contact. Part I: theoretical analysis and typical solution

Boundary film shear elastic modulus effect is analyzed in a hydrodynamic contact. The contact is one-dimensional composed of two parallel plane surfaces, which are, respectively, rough rigid with rectangular micro projections in profile periodically distributed on the surface and ideally smooth rigid. The whole contact is consisted of cavitated area and hydrodynamic area. The hydrodynamic area consists of many micro Raleigh bearings which are discontinuously and periodically distributed in the contact. Analysis is thus carried out for a micro Raleigh bearing in this contact. The hydrodynamic contact in this micro Raleigh bearing consists of boundary film area and fluid film area which, respectively, occur in the outlet and inlet zones. In boundary film area, the film slips at the upper contact surface due to the limited shear stress capacity of the film–contact interface, while the film does not slip at the lower contact surface due to the shear stress capacity large enough at the film–contact interface. In boundary film area, the viscosity, density and shear elastic modulus of the film are varied across the film thickness due to the film–contact interactions, and their effective values are used in modeling, which depend on the film thickness. The analytical approach proposed by Zhang (J Mol Liq 128:60–64, 2006) and Zhang et al. (Int J Fluid Mech Res 30:542–557, 2003) is used for boundary film area. In fluid film area, the film does not slip at either of the contact surfaces, and the shear elastic modulus of the film is neglected. Conventional hydrodynamic analysis is used for fluid film area. The present paper presents the theoretical analysis and a typical solution. It is found that for the simulated case the boundary film shear elastic modulus effects on the mass flow through the contact, the overall film thickness of the contact and the carried load of the contact are negligible but the boundary film shear elastic modulus effect on the local film thickness of the contact may be significant when the boundary film thickness is on the 1 nm scale and the contact surfaces are elastic. In Part II will be presented detailed results showing boundary film shear elastic modulus effects in different operating conditions.

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LANGMUIR—BLODGETT膜及其摩擦行为

本文回顾了Langmuir-Blodgett膜(简称LB膜)的发展简史,综述了各种类型LB膜的制备方法和利用其解决磁记录技术中超薄润滑问题的现状等,并且阐述了影响LB膜成膜质量的因素,论述了速度、负荷和LB膜之累积层数等对LB膜摩擦行为的影响。文章最后还提出了为把LB膜应用于摩擦学领域所必须深入研究的几个问题。作者认为,由于LB膜具有无与伦比的超薄和厚度容易控制,以及分子取向有序等诸多优点,故其除在磁记录技术中的应用外,对解决空间技术中的某些润滑问题及一些小负荷工况下的超薄润滑问题都将发挥重要作用。     

Stability of high‐speed two‐layer film casting of Newtonian fluids

The steady‐state flow and its linear stability are investigated for the isothermal two‐layer film casting process. Newtonian fluids are considered in this study. The continuity of traction is ensured at the interface, and the axial velocity is assumed to be uniform across each film layer separately. The effects of inertia, gravity, fluid parameters and processing conditions on the steady‐state flow and its stability are studied. The results indicate that the fluid properties and the processing conditions have significant influence on the flow. The flow stability is strongly dependent on the layer layout with respect to the take‐up rolling process. The frequency of the (unstable) disturbance is insensitive to flow and processing parameters. Copyright © 2006 John Wiley & Sons, Ltd.     

转移膜的形成对含氢碳膜超低摩擦性能的影响

含氢非晶碳膜在惰性气氛下展现了超低摩擦性能,摩擦系数可达到10~(–3)数量级.本文中通过试验设计验证了转移膜的形成是碳膜超低摩擦性能获得的必要条件.采用含氢非晶碳膜(a-C:H)与钢作为摩擦配副,球盘接触旋转运动,更换接触方式:一种是钢球与镀a-C:H薄膜的钢平板对摩,另一种是镀a-C:H薄膜钢球与钢平板对摩.保持配副材料不变,利用接触方式的差异,来改变转移膜形成的难易程度.第一种方式下,a-C:H可以转移到对偶形成均匀的转移膜,具有超低摩擦性能;在第二种方式下,a-C:H不能转移到对偶形成转移膜,摩擦系数高.而该转移膜是一种含氢的,以sp~2杂化为主的碳结构.氢能够参与钝化碳悬键,从而保证低化学作用活性,sp~2平面分子结构可以具有较低的剪切强度.因此,转移膜的形成和氢的钝化作用对a-C:H薄膜超低摩擦机理均具有重要的贡献.