Method for measuring adherence of a coating on a substrate
First Claim
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1. Process for measuring a bond of a coating on a substrate, comprising:
- sending ultrasounds into the substrate and into the coating;
picking up a series of echoes resulting from ultrasound reflections on faces of the substrate with an interface between the substrate and the coating;
evaluating an echo attenuation coefficient determining a decay in an amplitude of echoes as a function of a number of echo reflections; and
deducing the bond of a correlation function estimated in advance using calibration test pieces, between attenuation coefficients and values of the bond of the coatings determined by performing mechanical tests on calibration test pieces;
wherein the correlation function is obtained by manufacturing plural batches of calibration test pieces, the test pieces in each batch being identical, by tearing the coatings off the substrates by tension while measuring tear off resistance for each calibration test piece, and using a best tear off resistance in each of the batches as the resistance to tear off in the correlation function.
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Abstract
A process for measuring the bond of a coating on a substrate. Ultrasound echoes through the substrate of a test piece are collected and their amplitudes are measured, their decay being a function of the bond of a coating deposited on the opposite face of the substrate. Preliminary tests on calibration test pieces give a correlation function so that it is unnecessary to carry out expensive and uncertain mechanical tests on the test pieces.
19 Citations
12 Claims
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1. Process for measuring a bond of a coating on a substrate, comprising:
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sending ultrasounds into the substrate and into the coating;
picking up a series of echoes resulting from ultrasound reflections on faces of the substrate with an interface between the substrate and the coating;
evaluating an echo attenuation coefficient determining a decay in an amplitude of echoes as a function of a number of echo reflections; and
deducing the bond of a correlation function estimated in advance using calibration test pieces, between attenuation coefficients and values of the bond of the coatings determined by performing mechanical tests on calibration test pieces;
wherein the correlation function is obtained by manufacturing plural batches of calibration test pieces, the test pieces in each batch being identical, by tearing the coatings off the substrates by tension while measuring tear off resistance for each calibration test piece, and using a best tear off resistance in each of the batches as the resistance to tear off in the correlation function. - View Dependent Claims (2, 3, 4)
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5. Process for measuring the bond of a coating on a substrate, comprising:
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sending ultrasounds into the substrate and to the coating;
picking up a series of echoes resulting from ultrasound reflections on faces of the substrate, said faces comprising an interface between the substrate and the coating, evaluating an echo attenuation coefficient determining a decay in the amplitude of echoes as a function of the number of echo reflections on said interface, and deducing the said bond from a correlation function between values of said attenuation coefficients and values of the bond, said correlation function having been determined previously by performing mechanical tests on calibration test pieces. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
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Specification