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91.
研究了过滤阴极真空电弧技术中,不同的磁过滤器电流下(5—13 A),制备的四面体非晶碳(ta-C)薄膜对摩擦学特性的影响.通过对薄膜厚度,薄膜结构以及薄膜表面粗糙度随磁过滤电流的变化结果进行了测试,结果表明,随着磁过滤器电流的增大,薄膜的sp3键含量逐渐减少,表面粗糙度从0.13增大到0.38.磁过滤器电流在5 A时,薄膜的摩擦系数最小约为0.08,当电流增大到7 A时,摩擦系数显著增大,磁过滤器电流从7 A增大到13 A时,薄膜的摩擦系数再次减小约为0.1.
关键词:
四面体非晶碳
过滤阴极真空电弧
磁过滤器电流
摩擦系数 相似文献
92.
Electrical conductivity, internal friction techniques and dilatometer have been used to investigate the oxygen relaxation, phase transition and thermal expansion behavior of GdBaCo2O5 + δ. The main electronic charge carriers in GdBaCo2O5 + δ are electronic holes, which could be assigned to the formation of Co4+. The oxygen exchange kinetics intensely depends on oxygen partial pressure and is also closely related to temperature. Both electrical conductivity and internal friction give rise to an abnormal at about 75 °C, which are related to the insulator-metal transition occurring in GdBaCo2O5 + δ. One large relaxation internal friction peak, due to the motion of oxygen within Gd-O plane, is also found in the oxide. The average thermal expansion coefficient (TEC) of GdBaCo2O5 + δ is about 21.4 × 10−6 K−1 between 500 °C and 900 °C. 相似文献
93.
Microstructure and tribological behaviors of Ti6Al4V alloy treated by plasma Ni alloying 总被引:1,自引:0,他引:1
Zhenxia WangZhiyong He Yingqin WangXiaoping Liu Bin Tang 《Applied Surface Science》2011,257(23):10267-10272
Ni modified layer was prepared on surface of the Ti6Al4V substrate by plasma surface alloying technique. Surface morphology, micro-structure, composition distribution, phase structure, and microhardness of the Ni modified layer were analyzed. Tribological performance of the Ni modified layer and Ti6Al4V substrate was investigated by using pin-on-disc tribometer. The results indicate that roughness of the Ni modified layer was increased due to formation of the micro-convex on the modified surface. The concentration of Ni gradually decreased from the surface to interior. The maximum content of Ni atoms was nearly 90%. The modified layer was composed of TiNi, Ti2Ni and Ti phases. The maximum microhardness of the Ni modified layer was about 677 HV0.025 which was increased about two-fold of microhardness of the control Ti6Al4V substrate. Wear resistance of the Ni modified layer was improved obviously, and showed micro-abrasion wearing. The strengthened mechanism of the as-treated Ti6Al4V alloy is discussed. 相似文献
94.
95.
For the contact of two finite portions of interacting rigid crystalline surfaces, we compute the pinning energy barrier dependency on the misfit angle and contact area. This simple model allows us to investigate a broad contact-size and angular range, thus obtaining the statistical properties of the energy barriers opposing sliding for a single asperity. These data are used to generate the distribution of static frictional thresholds for the contact of polycrystals, as in dry or even lubricated friction. This distribution is used as the input of a master equation to predict the sliding properties of macroscopic contacts. 相似文献
96.
97.
The problem of finding the plane supporting curve (brachistochrone) along which a heavy particle released from rest at the given starting point slides with dry (Coulomb) friction and reaches the given destination point in least time, is stated as a variational isoperimetrical problem. The finite parametric equations of the extremal curve are obtained. This curve is the sought-for brachistochrone if the solution of the problem exists. Several numerical examples are given. 相似文献
98.
This paper presents a computer-based method for optimally sizing members of planar steel frameworks using commercially available standard sections. For first-order behavior and static loads, a minimum-weight structure is found while simultaneously ensuring stress and displacement performance conditions under applied service loads. Architectural conditions are imposed on section sizes to satisfy fabrication requirements related to member continuity and structure symmetry. The design method presented is iterative in nature and remarkably efficient. The number of iterations is generally quite small and almost totally independent: of the complexity of the structure. Designs are presented for two steel frameworks that are typical of those encountered in professional practise. 相似文献
99.
The use of an adjoint technique for goal‐based error estimation described by Hartit et al. (Int. J. Numer. Meth. Fluids 2005; 47 :1069–1074) is extended to the numerical solution of free boundary problems that arise in elastohydrodynamic lubrication (EHL). EHL systems are highly nonlinear and consist of a thin‐film approximation of the flow of a non‐Newtonian lubricant which separates two bodies that are forced together by an applied load, coupled with a linear elastic model for the deformation of the bodies. A finite difference discretization of the line contact flow problem is presented, along with the numerical evaluation of an exact solution for the elastic deformation, and a moving grid representation of the free boundary that models cavitation at the outflow in this one‐dimensional case. The application of a goal‐based error estimate for this problem is then described. This estimate relies on the solution of an adjoint problem; its effectiveness is demonstrated for the physically important goal of the total friction through the contact. Finally, the application of this error estimate to drive local mesh refinement is demonstrated. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
100.
Bearings, friction wheels, cams, etc. are widely employed elements in machine construction. The modeling of the dynamics of rolling friction plays therefore a crucial role in the simulation and optimization of such systems. This paper describes a recently developed transient-rolling-friction model with its application to different generic dynamical systems, to simulate the effects of rolling friction or traction on the dynamics of mechanical systems. The results, which are expressed in terms of the complex stiffness arising in the rolling-contact patches, show that the behavior depends on both the amplitude and the frequency of oscillation. For low amplitudes and frequencies, the behavior is quasi-linear. For increasing amplitudes and frequencies, however, strong non-linearities appear, leading to complex behavior. 相似文献