ACTIVE LOCK-IN THERMODYNAMIC METHOD FOR THICKNESS MEASUREMENT OF DIELECTRIC COATINGS
Journal: NDT WORLD
Volume 19 № 1
, 2016
Rubrics: ACTIVE THERMOGRAPHY
Authors:
3.
St. Petersburg Mining University
(kafedra «Priborostroenie», professor)
CONSTANTA Ltd (general'nyy direktor)
Sankt-Peterburg, Russian Federation
CONSTANTA Ltd (general'nyy direktor)
Sankt-Peterburg, Russian Federation
Type:
Article
Pages:
from 14
to 16
Status:
Published
Received:
02.03.2016
Accepted:
30.03.2016
Published:
30.03.2016
Language:
Russian
Keywords:
infrared thermography, thickness, coating, measurement
Abstract (English):
Introduction. The task of dielectric coating thickness measurement is regular for many industries. The object to be measured represents a two-layer structure with different static and dynamic parameters of the layers; the upper layer is dielectric. The analysis of physical processes taking place at active thermal loading of the object has shown that lockin temperature measurements of the object’s surface make it possible to measure its thickness, porosity and interlayer adhesion. Method. The structure of a noncontact active lock-in thermodynamic system for dielectric coating thickness measurement is offered. The system includes a flashlamp and a thermodynamic sensor with an optical unit. The technique for coating thickness measurement is developed on the base of the offered algorithm for analysis of primary temperature function T(τ), which shows the change of the excess coating surface temperature during heating and cooling. Results. The main matters of the method metrological provision are justificated including principles of reference stepped thickness standard development; questions of graduation, verification and calibration are considered. It is offered to use basic provisions of the active “National Verification System for Coatings Thickness Measurement Instruments” as well as the technology for metal thickness standard fabrication as most similar. Discussion. The main technical specifications of the system and examples of its applications in aerospace industry, mechanical engineering, and other industries show the correctness of the main theoretical provisions of the method and long-term benefit of using the system created on its base.
Introduction. The task of dielectric coating thickness measurement is regular for many industries. The object to be measured represents a two-layer structure with different static and dynamic parameters of the layers; the upper layer is dielectric. The analysis of physical processes taking place at active thermal loading of the object has shown that lockin temperature measurements of the object’s surface make it possible to measure its thickness, porosity and interlayer adhesion. Method. The structure of a noncontact active lock-in thermodynamic system for dielectric coating thickness measurement is offered. The system includes a flashlamp and a thermodynamic sensor with an optical unit. The technique for coating thickness measurement is developed on the base of the offered algorithm for analysis of primary temperature function T(τ), which shows the change of the excess coating surface temperature during heating and cooling. Results. The main matters of the method metrological provision are justificated including principles of reference stepped thickness standard development; questions of graduation, verification and calibration are considered. It is offered to use basic provisions of the active “National Verification System for Coatings Thickness Measurement Instruments” as well as the technology for metal thickness standard fabrication as most similar. Discussion. The main technical specifications of the system and examples of its applications in aerospace industry, mechanical engineering, and other industries show the correctness of the main theoretical provisions of the method and long-term benefit of using the system created on its base.
Keywords:
infrared thermography, thickness, coating, measurement
infrared thermography, thickness, coating, measurement
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