Investigation of Surface – Related Adhesion Failure

Importance of Surface and Interface Characterization Dr. Amir Hussain, Christa Pflugbeil COMTECH GmbH Labor für Kunststoffe comtech-labor.de, [email protected]

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 • • • • Contaminations eg. Grease, Wax, Oil, Silicone, Tenside Adsorbed Layers eg. Hydrocarbon, CO 2 , H 2 O Reacted Layers eg. Me-O, Me-O-H Bulk Material ca. 2-4 nm ca. 0,5-1 nm ca. 3-7 nm

Scope and Limits of Surface Analytical Techniques Technique FTIR Sensitivity > 1000 ppm Depth > 100 ppm Quantification Molecular Structure Indirect very good ESCA 1000 ppm 1-5 nm direct TOFSIMS < 0.1 ppm < 1 nm Indirect good very 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