importance of surface and interface characterization dr. amir hussain, christa pflugbeil comtech...
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Importance of Surface and Interface Characterization
Dr. Amir Hussain, Christa PflugbeilCOMTECH GmbH - Labor für Kunststoffecomtech-labor.de, info@comtech-labor.de
Investigation of Surface – Related Adhesion Failure
Materials and Surfaces
„Materials are indifferent, but the use we make of them is not a matter of indifference.“ (Epictetus 50 - 100 AD)
„GOD made materials but surfaces were the work of the DEVIL“ (Pauli)
Typical Structure of a Substrate Surface
• ContaminationsContaminations ca. 2-4 nmca. 2-4 nmeg. Grease, Wax, Oil, Silicone, Tensideeg. Grease, Wax, Oil, Silicone, Tenside
• Adsorbed LayersAdsorbed Layers ca. 0,5-1 nmca. 0,5-1 nmeg. Hydrocarbon, COeg. Hydrocarbon, CO22 , H , H22OO
• Reacted LayersReacted Layers ca. 3-7 nmca. 3-7 nmeg. Me-O, Me-O-Heg. Me-O, Me-O-H
• Bulk MaterialBulk Material
Scope and Limits of Surface Analytical Techniques
Technique Sensitivity Depth QuantificationMolecular Structure
FTIR > 1000 ppm > 100 ppm Indirectvery good
ESCA 1000 ppm 1-5 nm direct good
TOFSIMS < 0.1 ppm < 1 nm Indirectvery good
Lubricants / Contaminations detected on failed coating at the steel-FBE-interface
• Silocones (PDMS)
• Stearates / Fat
• Stearmide
Typical Contaminations on a Disbonded Interface (sample A) detected by ToFSIMS
Typical Contaminations on a Disbonded Interface (sample A) detected by ToFSIMS
Surface Contamination
• Surface Contamination is the most dangerous enemy of surface engeneering
• A controlled (pretreated) surface is more important than a perfect clean one
• Surface Analysis is the most effectice weapon against this enemy
Main Causes of Adhesive Failure in protective Coatings
• 65% Surface / Interface
• 20% Applications
• 15% Materials
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