Evaluating Specific Electrical Conductivity of Two-Layered Nonmagnetic Objects by Pulsed Eddy-Current Method

Russian Journal of Nondestructive Testing - Evaluating the specific electrical conductivity of two-layered nonmagnetic objects by the pulsed eddy-current method is considered. Eddy-current...     

Eddy-current control of the phase composition and hardness of metastable austenitic steel after different regimes of nanostructuring frictional treatment

The possibilities are studied for using an electromagnetic eddy-current technique of monitoring the phase composition and hardness of austenitic chromium–nickel steel that has been subjected to hardening frictional treatment in different technological regimes. It is shown that an eddy-current structuroscope and a Vektor eddy-current defectoscope make it possible to control the amount of straininduced martensite and the microhardness of the surface of metastable austenitic steel after nanostructuring frictional treatment with different numbers of gliding indenter scans (passes). The Vektor eddycurrent defectoscope allows one to monitor the phase composition of austenitic steel that has been subjected to nanostructuring frictional treatment in a temperature range from ?196 to +250°C.     

Eddy Current Testing of Metallic Materials Using Projection Methods

Using the example of nonmagnetic metallic materials, the projection methods of multidimensional analysis of multifrequency eddy-current testing measurement data presented for processing are considered. Based on the principal components method, the effects of electrical conductivity and sensor–material-surface gap on the results of testing have been separated. Using regression on principal components, the numerical values of the electrical conductivity and gap for manganese, copper, bronze, aluminum, and an aluminum alloy have been obtained. The results make it possible to extend the possibilities of nondestructive eddy-current evaluation of materials.     

Eddy-current quality control of soldering of current-carrying joints in electrical machines. I. General principles

The possibility of testing the electrical conductivity of soldered joints using and eddy-current transducer has been studied. The simplest model calculations allowing evaluation of the relative value of a signal from an inhomogeneity depending on its location inside a specimen are presented. It is shown that signals yielded by an eddy-current transducer are quite informative for determining the quality of soldering of current-carrying joints.     

VD-89NP Eddy-Current Flaw Detector

A new instrument—VD-89NP portable eddy-current detector—designed by ZAO Spectrum-RII is presented. The prototype instrument was the VD-89N eddy-current detector. Technical characteristics of the instrument and some features of its operation are described. Industrial applications of the instrument as a state-of-the-art detector are considered.     

SM-401 Magnetic Structuroscope

The SM-401 magnetic structuroscope is described. Operations carried out by means of the structuroscope and technical characteristics of the device are described. Factors determining the error in measurement of the coercive force are considered. The parameters of transducer of the magnetic structuroscope are estimated and the measurement results are outlined.     

A Modern Solution to Problems of Eddy-Current Structuroscopy

The problems arising during nondestructive quality tests of articles of nonmagnetic alloys and during sorting in the electrical conductivity are considered. The function and performance characteristics of a -26 eddy-current structruroscope are described. The structural diagram of this device and the algorithm of its operation are described. The capabilities of the -26 eddy-current structruroscope for performing nondestructive quality tests of thermal treatment of articles made of nonmagnetic materials are analyzed.     

Nondestructive testing of mechanical characteristics of aluminum alloys on the basis of their electrical conductivity

The results of studies of the interrelations between the mechanical characteristics of aluminum alloys applied in rocket and spacecraft engineering and electrical conductivity are presented. The conductivity was measured with a BЭ-26H instrument. The requirements for upgrading the conductivity-measuring device aimed at a further development of the methods for testing of the mechanical characteristics are formulated.     

Application of an Eddy-current method for the assessment of stored plastic deformation and residual mechanical properties after cyclic loading of an annealed medium-carbon steel

The effect of cyclic loading of annealed steel 45 during low-cycle fatigue on changes in its electrical characteristics is studied. In the region of both small and mediate strains, an eddy-current transducer signal is found to be highly sensitive to the plastic deformation stored during cyclic loading. Correlations between readings of an eddy-current instrument and the residual mechanical properties of the material after cyclic loading are obtained. The possibility of assessing the residual mechanical properties of the material during its cyclic loading is considered.     

Eddy-current quality control of soldering of current-carrying joints in electrical machines. II. Experiment

The possibilities of the eddy-current method for quality control of soldering of joints of stator copper windings in electrical machines are studied. The contribution of closed eddy currents, which are induced in inspected joints by an eddy-current transducer and differ in perimeters and location depths of joints, to the signal of the eddy-current transducer is considered experimentally. The information content of eddy-current transducer signals is shown to be sufficient for estimating the soldering quality of joints of this type. The effect of various technological factors on the reliability of the inspection was determined.     

Measurement of Electromagnetic Parameters of Metal-Coating Thickness Measures

Thickness measures for electrically conductive coatings applied to electrically conductive bases are described, for which not only geometrical but also electrophysical parameters such as the specific electrical conductivity and complex relative permeability of the measure base and the specific electrical conductivity of the measure coating are prescribed. The procedure and a technique for measuring the specific electrical conductivity of the base of a measure using the van der Pauw method, the complex relative magnetic permeability of metal on ring-shaped samples using a permeameter, a technique for transferring the value of this parameter to the measure base of an arbitrary shape with a flat surface, and also the procedure and a method for measuring the specific electrical conductivity of the coating-measure material with the use of an eddy current probe with a wave-like drive winding are described.     

Portable BΔ-12HΦM and BΔ-12HΦΠ eddy-current flaw detectors

The scope of application, specific features of design and operation, and the main technical characteristics of portable BΔ-12HΦM and BΔ-12HΦΠ eddy-current flaw detectors are considered.     

Application of the eddy-current method for estimating the wear resistance of hydrogen-alloyed β-titanium alloy BT35

The availability of the eddy-current method for the estimation of the wear-resistance under different wearing conditions and at different hydrogen contents in β-titanium alloy BT35 is studied. The alloy is hydrogenated to a hydrogen content of 0.10–0.38 wt % in a hydrogen atmosphere. The effect of the hydrogen content on the electrical resistivity of the alloy is studied. The peculiarities of using two types of eddy-current transducers (with a flat end surface and with a prominent ferrite rod-type core) for the analysis of electropolished surfaces and worn surfaces of titanium-alloy specimens are considered.     

On Possibility of Nondestructive Testing of the Grain Size in the Intermediate Stages of Manufacturing Electrical Steel

The results of investigation of the relation between the grain size in the intermediate stages of manufacturing electrical steel and various physical characteristics are given. The investigations are carried out for the purpose of clarifying the possibility of using these characteristics for arranging nondestructive testing of the grain size in the process of steel manufacturing. The paper contains the results of tests performed with the use of the methods of measuring the leakage magnetic fields on the grain boundaries by means of yttrium iron garnet films employed for visualization of the magnetic fields, the Barkhausen effect, the ultrasonic and eddy-current methods, the electromagnetic-acoustic conversion (EMAC) method, and the use of the relation between the grain size and the value of the coercive force.     

永磁涡流耦合传动特性研究

永磁涡流耦合传动技术采用非接触传动方式,能实现较软的传动特性,应用在一些特殊场合有非常好的效果。永磁涡流耦合器采用永磁涡流耦合传动技术,具有节能、过载保护、允许较大的对中误差、结构简单、使用寿命长等优点。为实现永磁涡流耦合传动特性研究,针对油田应用设计永磁涡流耦合器。对耦合驱动原理进行理论分析,建立永磁涡流耦合的数学模型;利用Ansoft仿真软件建立三维有限元模型,对耦合器的传动特性进行仿真研究,得到传递转矩与间隙、转速差之间的对应关系,随着间隙的减小,转速差的增大,耦合器传递转矩增加;建立耦合器传动试验平台,对样机进行试验研究,验证有限元仿真可以作为耦合器传动特性的研究方法,同时从试验结果曲线上确定耦合器合理的工作区间,在此工作区间内,耦合器具有高效率和较高的启动转矩,能够缓冲负载波动,传动性能良好。     

Functional Possibilities of SM-401 Magnetic Structuroscope

The possibilities of nondestructive testing the quality of product hardening using an SM-401 magnetic structuroscope with an H-shaped attached electromagnet are shown with references for ShKh15 and EI928 steels. Possibilities of the device for testing the quality of tempering products made from 40KhN2MA and wheel-tire steels are demonstrated.     

Magnetic and electromagnetic inspection of mechanical properties of high-carbon steel with an initial fine-pearlite structure subjected to high-temperature annealing

We study the possibilities of applying the measurements of major and minor magnetic hysteresis loops and electrical and eddy-current parameters for estimating changes in the strength and plastic characteristics of the high-carbon steel У 10 (with 1.03 wt % C) with a fine-pearlite structure during annealing at 650°C for 10–300 min. We analyze the correlations between the mechanical and physical properties of this steel with pearlite structures differing in morphology and imperfection of cementite, as well as the levels of solid-solution hardening and microdistortions of the ferrite-component lattice.     

The influence of a combined strain-heat treatment on the features of electromagnetic testing of fatigue degradation of quenched constructional steel

The possibilities of the magnetic and eddy-current methods for testing fatigue degradation during low-cycle loading of quenched steel 50 (0.51% C) that was subjected to a combined strain-heat treatment according to an optimal regime that included friction treatment with subsequent tempering at T = 350°C, were investigated. It is shown that for steel that was subjected to a combined nanostructuring treatment, the accumulation of a plastic strain under “hard” cyclic loading can be tested using the coercimetric method and values of the residual magnetic induction on the major and minor magnetic-hysteresis loops, values of the maximum and initial magnetic permeabilities, and readings of an eddy-current instrument at a low excitation frequency of the eddy-current transducer. The appearance of surface fatigue cracks can be tested via eddy-current measurements at high frequencies, when the contribution of the crack formation in the hardened layer to the eddy-current characteristics is considerable.     

High Lubricity of Re-Doped Fullerene-Like MoS2 Nanoparticles

The electrostatic effects in tribological systems have been studied in the past, especially with regards to data storage media. Nanoparticles (NP) of WS₂ and MoS₂ with fullerene-like structure (IF) have been studied in the past and showed very good tribological behavior. Being semiconductors, their electrical properties can be controlled by, e.g., substituting the lattice Mo (W) atoms with Re (n-type conductivity) and Nb (p-type conductivity) atoms. In this study doping of IF-MoS₂, and to a lesser degree IF-WS₂, NP with small amounts (< 1 at.%) of rhenium atoms has been studied. For this purpose two new synthetic approaches have been pursued. The doped nanoparticles were characterized by various techniques. In particular, the doping density was determined by ICP-MS technique. The resistivity of the nanoparticles was shown to decrease significantly with increasing doping level. In contrast to the undoped nanoparticles, the doped NP were shown to exhibit reduced agglomeration and produce stable suspensions in PAO-4 and PAO-6 oils. Extensive tribological measurements with these PAO oils formulated with 1 wt % of the doped NP showed friction coefficients as low as 0.01 in mixed lubrication conditions and negligible wear. Microscopy analysis of the tribological surfaces reveal very smooth but discontinuous and dense film of the doped NP on the tribological surfaces. It is proposed that the doped NP are negatively charged at their surface eliciting mutual repulsion, which has a remarkable influence on their rheological properties and their tribological behavior.