Patent ID: 6948370

Claim:
A method of measuring the adhesion of a coating to a substrate, consisting in sending ultrasound waves by means of a transducer toward the substrate and the coating, picking up a series of echoes resulting from reflections of the ultrasound waves on the surfaces of the substrate and of the coating, and calculating an amplitude ratio of two successive echoes, wherein the measurement is done in air and wherein the method also consists in applying the transducer to the substrate by means of a thin film of gel, calculating a coating quality factor given by the ratio between the amplitudes of the echoes associated with the first two reflections on the substrate/coating interface after passing through the substrate or on the coating/air interface after passing through the substrate and the coating, and in determining the adhesion of the coating from a correlation function between the quality factor and the breaking stress of the coating, obtained previously by mechanical tests on calibration test pieces.