高速开关阀位置控制方法

阐述了脉宽调制(PWM)控制的基本原理以及PWM信号的驱动方式，并以变量泵的排量控制为研究对象，通过对高速开关阀位置控制系统控制方法的理论分析和仿真研究，得出了一种基于常规控制手段的可提高高速开关阀位置控制系统精度的方法。     

Asymmetry of the yield strength in single crystals of titanium nickelide

Based on the results of the experimental studies of the temperature dependence of the yield stress of single crystals of TiNi alloys and of the mechanism of the mechanical twinning of the B2 phase as a martensite-type local reversible phase transformation, the asymmetry of the mechanical behavior of these materials during tension and compression in the [001] direction has been investigated. It is shown that a specific feature of this mechanism is the fact that the critical mode of distortion which determines stresses during mechanical twinning is a homogeneous deformation of transformation of the Bain-deformation type. To analyze the asymmetry of these stresses during tension and compression, a concept of the factor of normal stresses reduced to the principal axes of the tensor of the homogeneous deformation of transformation is introduced. It is shown that this factor can be used for analyzing the asymmetry of the mechanical behavior of single crystals of TiNi alloys.     

Corrosion Monitoring of Pipelines of Heat-Supply Systems Based on Gravimetric and Electrochemical Methods of Analysis

The aim of this work is to investigate the possibility of the application of the procedure for the prediction of the rate of corrosion for internal surfaces of the pipes of heat-supply systems. As a basis of the system for the evaluation of protective properties of oxide films, gravimetric studies and evaluation of the phase composition of films and their permittivity are chosen. The results of investigations of films show that it is possible to predict the rate of corrosion using not only gravimetric studies, but also the determination of the fraction of free surface and identification of the type and number of phases of the film. These procedures, being involved in the general system, make it possible not only to predict the corrosion process, but also to analyze reasons for its further development.     

Ten Years of the Russian Metallurgists Association and the 3rd Lakhtin Readings

The report is devoted to the 10th anniversary of the Russian Metallurgists Association (RASMET). The history of the appearance of the society of metallurgists in Russia is presented and the role of professor of Yu. M. Lakhtin, one of the creators of the theory and technology of nitriding in Russia, in the formation of the society is described. Lakhtin Readings are a scientific forum of specialists working in the field of thermochemical treatment. The role of IFHTSE in the organization and popularization of the Readings and the results of the 10-years work of RASMET are presented.     

Peculiarities of the macroscopic investigation of multicomponent electrochemichal deposits on the basis of the comparison of relative deviations

The paper presents an analysis of the available indicators of the correlation of the macroscopic distribution of the multicomponent electrochemical deposits and offers new indicators based on the principle of the comparison of the relative deviations from the average values of the sets of measurements of the dispersed parameters of electrochemical objects. The elaborated indicators reflect the correlation between the dispersed parameters with regard to the share in an aggregate (at the cathode macrolevel) of the compared feature of the relative deviations and allow for the objective checking of their estimation by other indicators. In addition, they enable a thorough investigation of the formation process of the multicomponent electrochemical deposits at the cathode macrolevel and application of their values for the purpose of the control and prediction of the functional structure of the deposits.     

Relaxation of interphase stresses on the later stages of the heterogeneous decomposition of solid solutions. II. Variational problem

The study of relaxation processes upon the decomposition of solid solutions at the stage of coalescence in the regime of dislocation-matrix diffusion is performed using a “precipitated-phase-particle-feeding-dislocations” system as an example. Within the framework of the variational approach, the cases of the independent and interdependent variation of the fraction of the relaxed regions of the interphase surface and of the number of edge dislocations which supply the alloying component to the precipitated phase have been investigated. Under the assumption that implies the linearity of the possible connection between these parameters, the model approximation of the continuous nucleation of epitaxial defects, and the absence of free matrix dislocations near the particle in the initial state, it is shown that the decrease in the number of edge feeding dislocations in the process of relaxation of interphase stresses can occur only by means of “leakage” of dislocation segments localized in the precipitate outside the limits of the precipitate with the formation of structural dislocation loops on the interphase surface.     

Special Features of Vacuum Carburizing of Heat-Resistant Steel in Acetylene

The mechanism of formation of the diffusion layer due to vacuum carburizing of complexly alloyed steel 16Kh3NVFMB-Sh (VKS5) in a medium of acetylene is considered. It is shown that the process of carburizing occurs in a self-regulation mode without the danger of carbon black due to the high rate of arrival of carbon from the gas medium as a result of catalytic dissociation of acetylene molecules, intense process of carbide formation on the saturated surface, and absence of catalytic activity of carbides. The diffusion layer forms under a thin layer of the carbide phase in a kinetic regime, the intensity of which is determined by the rate of dissolution of carbides.     

Structure of two-dimensional domain walls in two-layer permalloy films with a nonmagnetic interlayer

Structure of domain walls in two-layer Permalloy films separated by a nonmagnetic interlayer has been studied by the numerical minimization of the functional of the total energy of the domain wall in terms of a two-dimensional model of the magnetization distribution with an exact allowance for basic interactions (including exchange, magnetoanisotropic, and dipole-dipole interactions). Differences between the structure of these walls and that of single-layer films of analogous thicknesses have been investigated. The total energy (and its exchange and dipole-dipole components) per unit area of the surface of domain walls in two-layer films has been calculated as functions of the thicknesses of the Permalloy layers and the interlayer. The dependence of the thickness of magnetic layers at which there occurs a transition from the walls of the same type as in single-layer films of the corresponding thickness to walls of another type on the thickness of the interlayer has also been constructed. A comparison of the curve of this dependence with the experimental data is carried out.     

Electroerosion treatment of dielectric materials

The authors worked out a new method of combined electric-erosion and electric-chemical processing of dielectrics in an electrolytic medium. This article is dedicated to the study of the process of passing an electric current through an aqueous solution of an electrolyte. With the help of measurements of the voltampere characteristics of the current passing through the electrolytes under study, the total character of the electrolytes’ dependence, which has 4 transition regimes, was determined. The characteristics of the transition regimes depend on both the electric regimes and the types of electrolytes and their concentration and don’t depend on the distance between the electrodes. It’s characteristic of characteristic third phase that a plasma envelope appears that is accompanied by distraction of the dielectric. It’s shown that the tension and corresponding current density at which the plasma envelope occurs exist for every type of electrolyte when the material of the cathode is not changed. The correlation between these parameters and the coefficient of the surface-tension of the studied electrolytes is determined. The results of the study include the dependence of the speed of the volumetric broaching upon such technological parameters as the electric power, the frequency of the revolution of the electrode device, the frequency of the relaxation of the generator, and the concentration of the electrolyte. The problem of the mechanisms of the influence of the electric discharge in the electrolyte upon dielectric is discussed.     

Mechanisms of the Influence of Nitrogen on the Structure and Properties of Steels (A Review)

Special features of the structure of nitrogen-containing steels and the role of nitrogen in their hardening are considered. The following mechanisms of the action of nitrogen on the structure and properties of steels are analyzed: change in the state of solid solutions, shifting of the temperature of phase equilibria, segregation of nitride particles, interaction between nitrogen atoms and defects of crystal structure, and effect of nitrogen on the electron subsystem of the metal.     

The electronic factor in the act of adsorption of ions on a metal surface

The physical mechanism of the electron contribution to the electrochemical potential (intrinsic energy) of ions adsorbed on a metal surface is studied. The problem is reduced to consideration of the single-electron binding state in the fields of two attractors. For the bond between the anion and metal, the attraction centers are the potential of the atomic core of the anion and the potential reflecting the effects of interaction of the excess quantum charge with plasma degrees of freedom of the metal and formation of a surface axial plasmaron. On the average, the above attractors are neutral and are characterized by a finite range of action. The intrinsic energy of the cation of the metal surface depends on the energy of the valence electron in Coulombic fields of the cation itself, on the potential of the surface axial plasmahole, and on the energy of the mutual Coulombic repulsion of the above electron-attraction centers. Expressions are proposed for electronbinding terms of ions with a metal point by analogy with the mechanisms of formation of chemical σ- and π-bonds with partial charge transfer in molecular compounds.     

WEARING PERFORMANCE OF STEEL BALLS IN WET GRINDING

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Structural changes during superplastic deformation of high-strength alloy 1933 of the Al-Mg-Zn-Cu-Zr system

The strain rate-temperature conditions of manifestation of the effect of high-temperature superplasticity by samples of an 1933 alloy have been established. Features of the structural state, phase composition, and deformation relief of samples of this alloy have been investigated. It has been established that grain-boundary sliding occurs intensely along both boundaries of ultrafine grains and boundaries of coarse polygonized grains parallel to the tension axis of the sample. In near-surface grain-boundary pores and in cracks that were formed and developed at the surface of the working part of these samples in the course of superplastic deformation, fiber structures were detected. The chemical composition of fibers has been investigated. The kinetics of the occurrence of phase transformations in the 1933 alloy in the course of heating of its samples to the temperature of tests has been studied, and probable causes for partial melting of the 1933 alloy have been analyzed. Fracture mechanisms for the samples deformed superplastically under the optimum conditions have been established.     

Influence of preliminary deformation on the second-phase-particle size distribution in aging alloys

On the basis of a theoretical analysis of asymptotic states which are formed under the conditions of an enhanced density of matrix dislocations in different stages of decomposition of supersaturated solid solutions in concrete diffusion regimes, it is shown how the universal function of relative particle-size distribution is connected with the functional parameter m which is the only carrier of information on the amount of preliminary deformation ε of an aging alloy. This parameter as a function of ε is approximated by a step. The smearing and height of this step are determined from the found conditions of the realization of dislocation diffusion as the mechanism which controls coalescence in the initial and final (in the case of smallness of ε, very remote in time) stages of the evolution of a heterophase structure. Thereby, an explicit dependence of the universal distribution function on the deformation and the temperature and duration of aging is established.     

几何结构参数对磨料水射流喷嘴磨损规律影响的模拟分析

建立了前混合磨料水射流喷嘴物理模型。基于FLUENT软件,采用颗粒轨道模型、Grant弹性恢复系数和E/CRC磨损模型对磨料水射流喷嘴内的磨损特性进行了数值模拟。结果表明:当喷嘴收缩角为20°以上时,喷嘴磨损呈现两个严重磨损区,分别在喷嘴圆柱段入口处前较短距离范围内和喷嘴圆柱段出口处前较短距离范围内;随着喷嘴收缩角的增大,磨料颗粒与喷嘴圆柱段壁面碰撞次数和速度增加,同时随着喷嘴长径比的增大,喷嘴圆柱段壁面磨损速率整体增加,严重磨损区范围扩大,结果均使喷嘴圆柱段的磨损加剧。以喷嘴壁面磨损速率的面积加权平均积分表征喷嘴整体的磨损程度。随着收缩角和长径比的增大,喷嘴壁面磨损速率的面积加权平均积分增大,喷嘴的磨损整体而言越严重。因此,从减小喷嘴磨损的角度而言,喷嘴的收缩角和长径比宜取小值。     

Changes in the potential energy upon the formation of vacancies in the volume and in the cores of crystallite-conjugation regions in cubic polycrystalline metals

Changes in the potential energy of atoms that constitute the nearest neighborhood of vacancies formed in the bulk of d transition and precious cubic metals have been determined. These changes agree with the available first-principles calculations of changes in the potential energy of atoms of the nearest neighborhood of vacancies. In the cores of crystallite-conjugation regions (CCRs) of bcc polycrystalline d transition metals, the formation of vacancies is accompanied by positive changes in the potential energy of atoms of their nearest neighborhood. The absolute magnitudes of these changes are several times less than the changes in the potential energy of atoms of the nearest neighborhood of vacancies in the bulk of these metals, in accordance with the relationship between the enthalpies of formation of vacancies in these regions of polycrystals. The changes in the potential energy of atoms of the nearest neighborhood of vacancies formed in the cores of CCRs of fcc polycrystalline metals are negative because of the split structure of vacancies in the CCR cores of such metals.     

交变次数对楔横轧心部疏松的影响

应用ANSYS-DYNA有限元软件,对楔横轧轴类件进行轧制过程的模拟,以轧件1／2半径点的应力循环变化行为为基础,得到轧件中心截面的交变次数。选取了典型轧制实验模型与有限元分析结果做比较,得到交变次数对轧件心部疏松的影响规律,为深入研究楔横轧的疏松机理提供了依据。     

Strengthening of crystalline substances by programmed strain hardening

Conclusions Investigations of the mechanical and physical properties of metals at different loading rates and temperatures confirmed the existence of two types of hardening which differ in their physical nature — dislocation-substructural and diffusion.Diffusion hardening is practicable under conditions of programmed loading in which the rate of increase of external stress equals the rate of diffusion transfer of lattice defects. The structure of metals hardened by programmed loading is more uniform and mechanically more stable with respect to the original as the result of diffusion redistribution of point and line defects, pinning of dislocations, and the removal of local stress concentrations because of microplasticity, leading to release of dislocation pile-ups and their movement to the boundaries. The elimination of weak places with stress concentrations and the removal of structural heterogeneities (regions of potential nucleation of brittle cracks) after programmed loading is indicated by the uniform distribution of slip traces, improvement of the plastic properties, reduction of the static cold brittleness threshold, suppression of the Bauschinger effect, etc. The existence of the effect of programmed hardening in pure metals, the increase of the resistance to deformation without reduction of the plasticity, an improvement of the plastic properties for some metals, little change in the internal friction of iron in the temperature region of the carbon peak, and other results of the investigation indicate the fundamental difference between the mechanism of programmed hardening and ordinary age-hardening.The distinguishing characteristics of the method of programmed hardening are the increased resistance to deformation and simultaneous improvement of the combination of physical properties, the higher margin of plasticity, the stability of the microstructure with respect to recrystallization, the attainment of hardening with very small remanent strain (0.01–0.5%).Physicotechnical Institute of the Academmy of Sciences of the UkrSSR. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No.5, pp.2–8, May, 1967.     

卡箍对L形航空液压管道振动影响研究

利用ANSYS对L形航空液压管道进行仿真分析,研究装配不同数量卡箍及卡箍约束不同位置对L形管道固有频率的影响.分析添加不同数量卡箍后管道在脉动流体作用下最大范式应力的变化.结果表明:在管道长度一定的情况下,适当增加卡箍数量以及改变卡箍的约束位置对于管道频率有明显的提高效果;随卡箍数量的增加,管道在脉动流体作用下的最大范式应力逐渐减小,但卡箍约束对管道流体脉动最大应力的影响幅值降低.     

浮选药剂的亲固能计算

在浮选体系下，药剂和矿物的作用不仅和键合原子有关，还和矿物表面相邻原子、药剂亲固基团以及介质水分子有关。在此模型下提出了药剂亲固基团和矿物表面作用能的计算公式，利用这一公式可定量研究矿物表面极性、药剂分子极性和介质水分子对浮选药剂亲固能的影响。研究结果表明，浮选介质分子水影响药剂和矿物表面作用能的强弱，对于极性较小的矿物（如硫化矿物），其表面和药剂亲固基团的作用能与基团电负性成反比，基团电负性越小，作用越强；对于极性较大的矿物（如非金属矿物），其表面和药剂亲固基团的作用与基团电负性成正比，基团电负性越大，作用越强。