Corrosion evaluation of coated sheet metal by means of thermography and image analysis

Per Jernberg

doi:10.1117/12.46443

1 March 1991 Corrosion evaluation of coated sheet metal by means of thermography and image analysis

Per Jernberg

Proceedings Volume 1467, Thermosense XIII; (1991) https://doi.org/10.1117/12.46443
Event: Orlando '91, 1991, Orlando, FL, United States

Abstract

The fact that organic binders, as used in paints, are transparent in the IR range 3.5-5.5 microns is utilized to detect and measure defects under the paint film of sheet metals. However, the method demands an elevated sample temperature to suppress reflections from the surrounding and is till now resorted to laboratory investigations. The IR system used is an AGEMA Thermovision 880 SWB. The maximum thickness of the paint film allowing evaluation is mainly governed by the absorption and the refraction caused by the paint pigments, depending upon pigment size and pigment material. To be detectable the defects have to be characterized by IR emissivities considerably different from the emissivity of the bare sheet metal as is found for metallic corrosion products. A quantitative determination of a corrosion attack is obtained by evaluating the IR image at a PC based image analyzer. As a standard today, such evaluations are performed by inspecting and comparing painted sheet metals with reference photographs. This method suffers both from the subjectiveness of the observer and the opaqueness of the paint film in the visible range.

Citation Download Citation

Per Jernberg "Corrosion evaluation of coated sheet metal by means of thermography and image analysis", Proc. SPIE 1467, Thermosense XIII, (1 March 1991); https://doi.org/10.1117/12.46443

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available