Microwave Non-Destructive Testing of Coatings and Paints Using Free Space Microwave Measurement

2005 ◽  
Vol 2 (2) ◽  
pp. 17
Author(s):  
Norhayati Hamzah ◽  
Deepak Kumar Ghodgaonkar ◽  
Kamal Faizin Che Kasim ◽  
Zaiki Awang
Keyword(s):  
Free Space ◽  
Protective Coatings ◽  
Microwave Measurement ◽  
Multiple Reflections ◽  
Destructive Testing ◽  
Lens Antennas ◽  
Coatings And Paints ◽  
Microwave Nondestructive Testing ◽  
Mode Transitions ◽  
Diffraction Effects

Microwave nondestructive testing (MNDT) techniques are applied to evaluate quality of anti-corrosive protective coatings and paints on metal surfaces. A tree-space microwave measurement (FSMM) system is used for MNDT of protective coatings. The FSMM system consists of transmit and receive spot-focusing horn lens antennas, a vector network analyzer, mode transitions and a computer. Diffraction effects at the edges of the sample are minimized by using spot-focusing horn lens antennas. Errors due to multiple reflections between antennas are corrected by using free-space LRL (line, reflect, line) calibration technique. We have measured complex reflection coefficient of polyurethane based paint which is coated on brass plates.

scholarly journals Roll-to-Roll In-Line Implementation of Microwave Free-Space Non-Destructive Evaluation of Conductive Composite Thin Layer Materials

2021 ◽  
Vol 11 (1) ◽  
pp. 378
Author(s):  
Grigorios Koutsoukis ◽  
Ivan Alic ◽  
Antonios Vavouliotis ◽  
Ferry Kienberger ◽  
Kamel Haddadi
Keyword(s):  
Thin Film ◽  
Composite Materials ◽  
Free Space ◽  
Near Field ◽  
Line Production ◽  
Roll To Roll ◽  
Corrugated Horn ◽  
Evaluation Module ◽  
Microwave Nondestructive Testing ◽  
Non Destructive

A free-space microwave nondestructive testing and evaluation module is developed for the low-power, non-ionizing, contactless, and real-time characterization of doped composite thin-film materials in an industrial context. The instrumentation proposed is built up with a handled vector network analyzer interfaced with corrugated horn antennas to measure the near-field complex reflection S11 of planar prepreg composite materials in a roll-to-roll in-line production line. Dedicated modeling and calibrations routines are developed to extract the microwave conductivity from the measured microwave signal. Practical extraction of the radiofrequency (RF) conductivity of thin film prepreg composite materials doped with nano-powders is exemplary shown at the test frequency of 10 GHz.

scholarly journals Method of Multi-Angle Transmission Radiowave Tomography of Dielectric Objects

2020 ◽  
Vol 10 (9) ◽  
pp. 3270
Author(s):  
Dmitry Sukhanov ◽  
Kseniya Zavyalova
Keyword(s):  
Refractive Index ◽  
Time Delay ◽  
Homogeneous Medium ◽  
Projection Algorithm ◽  
Propagation Time ◽  
Destructive Testing ◽  
Internal Structures ◽  
Diffraction Effects ◽  
Dielectric Objects ◽  
Non Destructive

A method for solving the inverse problem for reconstructing the spatial distribution of dielectric permittivity from the results of multi-angle transmission broadband radiosounding is proposed. The method is based on inverse wave propagation. The average refractive index of the medium along the wave trajectory is calculated by comparing the results of the calculation of the time delay of the inverse signal in the entire sounding region and the forward propagation time in a homogeneous medium. This method takes into account diffraction effects in solving a direct problem, which allows one to obtain a resolution in the order of a wavelength. The combination of time delays obtained at different probing angles allows the restoration of the distribution of the refractive index in the medium. The paper presents the results of the numerical simulation of this method. The novelty of the proposed approach compared to the conventional back-projection algorithm is that ray approximation is not applied. Instead of the absorption coefficient (used in X-ray tomography), a time delay is considered, which is restored in the entire probed region. The developed method can be widely used in radiowave tomography or microwave tomography for remote non-destructive testing, diagnostics for the internal structures of inhomogeneous media and the restoration of the shapes of opaque objects based on multisensor sensing.

THE HIGH VOLTAGE TESTING OF DIELECTRIC COATINGS THICKNESS

2020 ◽  
pp. 12-17
Author(s):  
V. A. Syasko ◽  
S. S. Golubev ◽  
A. S. Musikhin
Keyword(s):  
High Voltage ◽  
Protective Coatings ◽  
Coating System ◽  
Large Area ◽  
Destructive Testing ◽  
Minimum Thickness ◽  
Dielectric Coatings ◽  
Internal Surfaces ◽  
Comparative Results ◽  
Tolerance Control

The technology of applying many coatings (including paints and varnishes) involves the layering of visually indistinguishable layers that make up the coating system. However, in case of application technology violation, the number of coating layers (thickness) may not correspond to the declared. Thus, in a number of cases, it is necessary to control the number of layers of the final coating system. One of the most common methods for monitoring the continuity of coatings is the high voltages spark method of non-destructive testing. The method involves the application of a high voltage U between the electrode installed on the surface of the coating and the conductive substrate. The revealing of defect coating area provide by registering the coating breakdown. The analysis shows that the development of methods for detecting not only discontinuities, but also unacceptable thinning of dielectric coatings due to their spark breakdown, seems to be a promising direction in the development of high voltages spark testing. In relation to pulsed high voltages spark testing, the electrical mechanism of the breakdown of dielectrics based on quantum-mechanical concepts, the conditions of its occurrence, and the main relations obtained for calculating the electric strength Es and breakdown voltage Us for protective dielectric coatings are considered in detail. Comparative results of an experimental study of the proposed algorithms for calculating Es and Us, as well as methods for identifying (tolerance control) sections of paint coatings with an unacceptable minimum thickness and coating bubbles, are presented. The application of the proposed algorithms and methods will allow one hundred percent control of the continuity and unacceptable thinning of paint and varnish and similar dielectric protective coatings of the external and internal surfaces of pipelines, as well as various large area facilities.

scholarly journals Scattering from a Buried PEMC Cylinder Illuminated by a Normally Incident Plane Wave Propagating in Free Space

2018 ◽  
Vol 8 (1) ◽  
pp. 1-7 ◽  
Author(s):  
A. Hamid ◽  
F. Cooray
Keyword(s):  
Plane Wave ◽  
Half Space ◽  
Free Space ◽  
Transverse Magnetic ◽  
Planar Interface ◽  
Burial Depth ◽  
Multiple Reflections ◽  
Incident Plane ◽  
Plane Wave Incident ◽  
Expansion Coefficients

A rigorous solution is presented to the problem of scattering by a perfect electromagnetic conducting (PEMC) circular cylinder buried inside a dielectric half-space that is excited by a normally incident transverse magnetic (TM) plane wave propagating in free space. The plane wave incident on the planar interface separating the two media creates fields transmitting into the dielectric half- space becoming the known primary incident fields for the buried cylinder. When the fields scattered by the cylinder, in response to those fields incident on it, are incident at the interface, they generate fields reflected into the dielectric half-space and fields transmitted into free space. These fields, and the fields scattered by the cylinder are expressed in terms of appropriate cylindrical waves consisting of unknown expansion coefficients which are to be determined. Imposing boundary conditions at the surface of the cylinder and at a point on the planar interface, enables the evaluation of the unknown coefficients. This procedure is then replicated, by considering multiple reflections and transmissions at the planar interface, and multiple scattering by the cylinder, till a preset accuracy is obtained for the reflection coefficient at the particular point on the interface. The refection coefficient at this point is then computed for cylinders of different sizes, to show how it varies with the PEMC admittance of the cylinder, its burial depth, and the permittivity of the dielectric half-space.

scholarly journals Electronics-Based Free-Space Terahertz Measurement Using Hemispherical Lens Antennas

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 95536-95546
Author(s):  
Nonchanutt Chudpooti ◽  
Natapong Duangrit ◽  
Prayoot Akkaraekthalin ◽  
Ian D. Robertson ◽  
Nutapong Somjit
Keyword(s):  
Free Space ◽  
Lens Antennas
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