Quantitative evaluation of adhesion quality of surface coating by using pulse laser-induced ultrasonic waves

Abstract

This study aims to evaluate delamination characteristics of surface coating by using strong ultrasonic wave induced by pulsed laser irradiation. Strong tensile stress wave is induced by pulse laser irradiation, and delamination of the coating layer/substrate interface (or spallation) is produced by confined silicone grease breakdown (i.e. ablation). Upon various levels of energy of irradiation laser, the coating delamination and displacement are measured in-situ. Parallel computation of elastic wave propagation using FDTD (finite difference time domain) yields the wave propagation in the specimen, and estimates the interfacial strength with stress wave distribution. The delamination area is visualized by laser ultrasonic wave scanning technique after the laser spallation test. The interaction between displacement waveform and delamination is explored. The present technique may shed some light on various coating depositions for assessing the coating adhesion quality.

Nanotribological, nanomechanical and interfacial characterization of atomic layer deposited TiO2 on a silicon substrate

“…Watanabe et al used pulsed laser irradiation on the backside of the test structure to create a strong ultrasonic wave to evaluate delamination characteristics of an electroplated nickel coating on a steel substrate (Watanabe, 2016). Ostrowicki et al used a magnetically actuated peel test setup resembling island blister testing, where they attached a permanent magnet to the tested film and used an electromagnet below the sample to delaminate the coating (Ostrowicki, 2012).…”

Nondestructive measurement of mill-scale thickness on steel by terahertz time-of-flight tomography

“…To date, various nondestructive-evaluation (NDE) techniques have been explored to study the structure and condition of coatings on metals, such as electrochemical impedance spectroscopy (EIS) [1], scanning electrochemical microscopy [2], acoustic emission [3], thermography and eddycurrent testing [4]; however, not all of the techniques are capable of providing quantitative information in depth such as the layer thickness. Approaches such as scanning acoustic microscopy [5] and laser ultrasonic imaging [6] suffer from high attenuation at the requisite high frequencies which limits the penetration of ultrasound waves into the sample.…”

Advances in test and measurement of the interface adhesion and bond strengths in coating-substrate systems, emphasising blister and bulk techniques

“…A schematic setup of the pulse laser-induced surface acoustic wave detection device is shown in Fig.16. Fig.16 Schematic setup of the laser acoustic wave measuring systems [126] To measure the out-of-plane-displacement velocity, a high frequency-response non-contact sensor, such as a high dynamic responding laser ultrasonic interferometer [127], is needed. The degree of damage and damage dimensions (i.e.…”

“…where σ is the normal stress, ρ is the material density, CL is the longitudinal wave velocity, and ∂u/∂tis the velocity of out-of-plane displacement of the coating. Arai et al [129] have undertaken an experiment with a laser spallation setup similar to that reported in [127] and used a laser interferometer to measure the stress wave de-bonding displacement velocity using a Ti-coated film on an Al-alloy substrate. As part of this, they analyzed the bond fracture toughness using a transfer function computed from the recorded displacement.…”