Nondestructive Assessment of Anticorrosive Aluminium Coatings by Active Infrared Thermography

Abstract

The thermal sprayed coating layers are commonly used in industrial applications aiming to protect certain heavy loaded components. Depending on the specific application, they may be used as thermal barriers for base materials protection, for increasing the wear resistance or corrosion resistance in aggressive environments. Due to the importance of each specific application, the nondestructive evaluation of these coating layers is a current demand. The paper presents a NDT technique for quality assessment of Anticorrosive Aluminium Coatings by non-contact Active Infrared Thermography (IRT). This NDT method allowed obtaining useful quantitative information on sub-superficial lack of adhesion flaws (size and position). The paper also presents a thermogram processing algorithm for quantitative assessment of components imperfections. This processing algorithm was designed and implemented using the JavaTM technology, based on the following modules: image enhancing, image pre-processing, histogram and flaw area evaluation. The functionality of each module is described and illustrated by examples consisting of both monochrome (grey) and colour thermographic image sets.