Surface Modification of Metallic Inserts for Enhancing Adhesion at the Metal–Polymer Interface

Abstract

A combination of mechanical and chemical treatments was utilized to modify the surface textures of copper and duralumin inserts in order to enhance the adhesion at the metal–polymer interface and provide an adhesive joint with a high loadbearing capacity. Pretreatment of the surfaces with sandblasting was followed by etching with various chemical mixtures. The resulting surface textures were evaluated with a scanning electron microscope (SEM) and an optical confocal microscope. Surface geometry parameters (Sa, Sz, and Sdr) were measured and their relationships to the adhesion joint strength were studied. It was found that the virgin and purely mechanically treated inserts resulted in joints with poor loadbearing capacity, while a hundredfold (duralumin) and ninetyfold (copper) increase in the force to break was observed for some combinations of mechanical and chemical treatments. It was determined that the critical factor is overcoming a certain surface roughness threshold with the mechanical pretreatment to maximize the potential of the mechanical/chemical approach for the particular combination of material and etchant.

Precepts for Designing Sandwich Materials

“…It can be carried out mechanically by brushing, grit blasting, or grinding to increase the anchorage possibilities [32,33]. Chemical treatments such as electrochemical etching, anodisation, and the addition of adhesive promoters can all be used to improve adhesion [34,35]. Moreover, it can also be accomplished physically using techniques such as laser treatment, corona treatment, or plasma treatment [36][37][38].…”

Bioelectronic Neural Interfaces: Improving Neuromodulation Through Organic Conductive Coatings

“…[185,230] Plasma cleaning, degassing with hot air or steam, and UV zone treatment further aid in comprehensive metal surface preparation. [231] For polymer-coated neural stimulating electrodes used in vivo, repetitive charging and discharging of the conductive coating is known to induce internal stress that may lead to imperfec-tions or microcracks, enabling rapid fluid ingress into the interface. Water molecules are excellent hydrogen bonds donor and acceptor, they can readily hydrolyze hydrogen or even covalent bonds formed at polymer-metal interface.…”

On the Use of Polymer-Based Composites for the Creation of Optical Sensors: A Review

“…Since a composite is a material consisting of at least two phases separated by an interface border, it is essential that its components have appropriate adhesion to each other [ 189 ]. Otherwise, a significant decrease in mechanical strength could be observed, which may result in rapid destruction of the heterogenous material [ 188 , 190 , 191 , 192 , 193 ].…”

“…If metal inserts are used in the composite, their surface texture changes can be made through a combination of mechanical and chemical processing in order to increase adhesion at the metal-polymer interface and provide a high bearing capacity with adhesive joint [ 189 ]. The corundum mechanical treatment followed by the proper chemical etching gave the best results.…”