Characterization of the adhesion of coatings by surface acoustic waves generated and detected by laser sources - Archive ouverte HAL
Thèse Année : 2024

Characterization of the adhesion of coatings by surface acoustic waves generated and detected by laser sources

Caractérisation de l'adhérence des revêtements par ondes acoustiques de surface générées et détectées par sources laser

Résumé

This thesis focuses on material adhesion, which is often crucial to the reliability of coating technologies. More precisely, the adhesion quality of a polyvinyl chloride film to an aluminum substrate is evaluated by Laser-Ultrasonics. Indeed, this non-contact and non-destructive method allows to excite surface acoustic waves (SAW) in layer-on-substrate structures, whose propagation can be sensitive to adhesion. Experimentally, these guided waves are excited by a frequency-doubled Nd:YAG laser and detected via a Mach-Zehnder heterodyne interferometer. To avoid coating thickness variations that would interfere with acoustic wave propagation, It is preferable not to consider an intermediate adhesive layer. Therefore, for the first time, we are using an electro-adhesion device that allows the adhesion level of the dielectric layer to the substrate to be modified by simple voltage adjustments. A program has been developed to obtain the Rayleigh modes dispersion curves considering the effect of normal and tangential stiffnesses. In addition, finite element method is implemented to simulate SAW propagation under varied adhesion conditions. The results clearly show the sensitivity of these waves to electrostatically induced variations in the quality of film adhesion only.
This thesis focuses on material adhesion, which is often crucial to the reliability of coating technologies. More precisely, the adhesion quality of a polyvinyl chloride film to an aluminum substrate is evaluated by Laser-Ultrasonics. Indeed, this non-contact and non-destructive method allows to excite surface acoustic waves (SAW) in layer-on-substrate structures, whose propagation can be sensitive to adhesion. Experimentally, these guided waves are excited by a frequency-doubled Nd:YAG laser and detected via a Mach-Zehnder heterodyne interferometer. To avoid coating thickness variations that would interfere with acoustic wave propagation, It is preferable not to consider an intermediate adhesive layer. Therefore, for the first time, we are using an electro-adhesion device that allows the adhesion level of the dielectric layer to the substrate to be modified by simple voltage adjustments. A program has been developed to obtain the Rayleigh modes dispersion curves considering the effect of normal and tangential stiffnesses. In addition, finite element method is implemented to simulate SAW propagation under varied adhesion conditions. The results clearly show the sensitivity of these waves to electrostatically induced variations in the quality of film adhesion only.
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Dates et versions

tel-04753747 , version 1 (25-10-2024)

Identifiants

  • HAL Id : tel-04753747 , version 1

Citer

Mustapha Baher. Characterization of the adhesion of coatings by surface acoustic waves generated and detected by laser sources. Acoustics [physics.class-ph]. Université Polytechnique Hauts de France, 2024. English. ⟨NNT : ⟩. ⟨tel-04753747⟩
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