Evaluation of the coating–substrate adhesion by laser-ultrasonics: Modeling and experiments

Abstract

The aim of the present study is to investigate a laser-ultrasonic method to determine the oxide-coating's adhesion strength on a metallic substrate. In order to demonstrate this method a completely contactless system is used, combining laser generation and detection of ultrasonic waves. A nanosecond pulsed Nd:YAG laser is used to irradiate the transparent oxide coatings, while the normal displacement of the rear surface of the metallic substrate is detected at the epicenter by a laser heterodyne interferometer. Increasing the laser beam energy, the generated acoustic wave forms are correlated with the thermoelastic regime, the fracture of the coating-substrate interface, and finally the expulsion of the coating. The generation of ultrasonic signals in the thermoelastic regime is described by a two-dimensional model suitable to calculate the in-and out-of-plane components of the mechanical displacement versus time. The values of the so-called practical adhesion found are in agreement with those obtained by classic contact techniques ͑tensile adhesion test, indentation, bending test͒. This work demonstrates the suitability of this quantitative and contactless test to evaluate the coating-substrate adhesion.

Corrosion Behavior Evaluation of Coated Steel Using Fiber Bragg Grating Sensors

“…When the coatings failed, the underlying structure would be exposed to corrosive environment and subjected to corrosion attacks. To ensure the proper functionality of coatings, multiple types of technologies can be applied to verify the performance of coatings as well as to predict service life, including destructive and non-destructive techniques [7,[14][15][16][17][18][19][20][21][22][23][24].…”

Cracking analysis of HVOF coatings under Vickers indentation

“…4 Non-standard test methods are also developed such as laser spallation 5 and ultracentrifugal tests. 6 There are also quality control test methods such as peel test, 7 hammering test, 8 and so on. Instead of measuring the adhesive strength, many testing methods have also been devised to measure the fracture energy of the coating/substrate interface-a fundamental measure of the adhesion.…”

Measurement of interfacial toughness of metal film wire and polymer membrane through electricity induced buckling method

“…Measuring interfacial bonding strength often requires an optical dynamic monitoring system [7,8], which monitors the surface displacement waveforms of a film wire and a substrate. This method needs complicated test equipment and high environmental condition, and it is not suitable for a film wire with width of micro/nanoscale.…”