Radiation pattern of ultrasonic transducer with polymer-powder matching layer

© 2018 IEEE. The work is devoted to the study of the radiation pattern of the ultrasonic transducers. Transducers modified by deposition in the electrostatic field of a protective matching quarter-wave polymer-powder layer. It is shown that the use of the matching layer does not significantly change the radiation pattern of the transducers. The presented results show the dependence of the radiation pattern on the frequency. It is shown that the width of the main lobe of the radiation pattern becomes narrower with an increase in the resonance frequency of the transducer

Experimental study of the polymer powder film thickness uniformity produced by the corona discharge

© Published under licence by IOP Publishing Ltd.The results of an experimental study of the polymer powder film thickness uniformity are presented. Polymer powder films are produced by the electrostatic field of corona discharge. Epoxy and epoxy-polyester powder films with thickness in the range of 30-120 microns are studied. Experimentally confirmed possibility of using these coatings as protective matching layer of piezoceramic transducers at frequencies of 0.5-15 MHz

Sensitivity and directivity measurement of ultrasonic transducer with polymer-powder matching layer

© Published under licence by IOP Publishing Ltd. The results of an experimental study of the sensitivity and directivity pattern of the ultrasonic transducers are presented. Data was obtained for transducers with central frequency at 2.5 and 5 MHz with protective matching layers, in comparison with transducers without matching layers. Increase of transducer sensitivity is shown. In addition, it is shown that the directivity patterns for transducers with the matching layer and without it are practically identical. Also was observed that the directivity pattern gets sharper as the frequency of the transducer increases

Acoustic sensing method based on the inverse problem of recovering the density profile and the bulk modulus of the inhomogeneous medium

© Published under licence by IOP Publishing Ltd. The model of inhomogeneous acoustic medium without loss in dimensional approximation based on the Riccati equation for the impedance of the medium is considered. The inverse operator problem of recovering the coefficients of the Riccati equation is formulated. The numerical algorithm for solving the problem based on the integral equation coupling input acoustic impedance or admittance to the distributions of density or bulk modulus of the medium is proposed. The method of acoustic scanning is proposed. The numerical simulation of the proposed algorithm is carried out

Corona discharge in the process of spraying protective powder coatings on piezoceramic materials

© 2014 by Begell House, Inc. The objects of research are powder coatings and the technology of their application to ultrasonic piezoelectric elements. The results of studies of the distribution of coating thickness for different modes of coating application are presented. The results of simulation of the gas suspension motion in the electrostatic field in the needle–plane electrode system have been confirmed experimentally

Resistance of the powder coatings obtained in the electrostatic field of the corona discharge to the static action of liquids

© 2018 Institute of Physics Publishing. All rights reserved. The results of an experimental study of the static action of liquids on polymer-powder coatings obtained in the electrostatic field of the corona discharge are presented. Epoxy, epoxy-polyester, polyester, polyurethane and silicone powder materials have been studied. It has been shown experimentally that epoxy-polyester coating EP111095G is resistant, while epoxy EX611434SG, polyester PD810119G, polyester PD510226G and polyurethane PD010186G coatings are relatively resistant

The spatial distribution the thickness of polymer powder coatings for ultrasonic sensors

© Published under licence by IOP Publishing Ltd. Objects of research are coatings and technology of their applying to the piezoelectric elements for ultrasound. Results of studies the distribution coating thickness according to different modes of coating process are presented. Experimentally confirmed the simulation results of the movement gas suspension on the electrostatic field in the electrode system "needle - plane"

Protective matching polymer powder coating of piezoelectric element

Objects of research are coatings and technology of their applying to the piezoelectric elements for ultrasound. Acoustic impedance and thicknesses of matching layers for medical ultrasound transducers have been defined. In this paper performance characteristics of coating systems with predetermined properties have been selected. The conditions for selection of polymer powder paint for quarter wave matching layer have been determined. Conditions of forming polymer powder coatings have been proposed. © Published under licence by IOP Publishing Ltd

Process of the Deposition of Charged Polydisperse Gas Suspension on the Plate Surface in an Electrical Field

© 2018, Pleiades Publishing, Ltd. The process of powder sputtering onto a flat surface in an electric field is described on the basis of the numerical solution of a system of equations of the dynamics of a polydisperse gas suspension. The model includes equations for the motion of the carrier and disperse phases under the action of the aerodynamic friction force and the Coulomb force, taking into account the interphase exchange of momentum and energy. The system is solved by the explicit predictor–corrector method with splitting over the spatial directions and the nonlinear correction scheme. The numerical model is used to obtain the velocity and density fields of the gas suspension in the interelectrode space and on the surface of the target electrode

Numerical simulation of vortex structures in the spraying of electrically charged gas suspension on a plate

© 2018 Institute of Physics Publishing. All rights reserved. Based on the numerical solution of polydisperse gas suspension dynamics system of equations, the process of powder spraying on a plane surface in an electric field is described. The model includes motion equations of the carrier medium and disperse phase fractions under aerodynamic friction and Coulomb forces action taking into account interfacial exchange of pulse and energy. The system solves by an explicit predictor-corrector method with splitting on the spatial directions and the non-linear correction scheme. The numerical model is applied to gas suspension speed and density fields receiving in interelectrode space and on target electrode surface. The system of equations was written in the generalized curvilinear coordinates: the physical region of a current in variables (x, y) was written in a canonical computational region in variables (ξ,η) and was solved by an explicit second-order Mac-Cormack method. The Poisson equation for the electric field potential was written in the generalized coordinates and was solved by finite difference method with the use of the iterative Seidel scheme on a gas-dynamic computational mesh