Surface topology modification of organic substrates using material jetting technologies

Abstract

The ability to directly modify the topology of a surface with three-dimensional micron-scale features provides both a mechanism of controlling how it interacts with the surrounding environment and the potential to impart functional features. Using direct material jetting based additive manufacturing technologies, we report the direct printing of microstructures onto aluminium coupons previously finished with polyurethane (PU) coatings where the overcoat window proved crucial for this process. The effect of PU coating's age on the development of strong interfacial interactions and hence the level of adhesion achieved between the photopolymer and the topcoat was explored. With aging, the PU coatings were shown to increase in cross-link density which resulted in reduced levels of adhesion with the photopolymer observed. This was reflected in changes in surface energy hence surface chemistry via XPS analysis. Changes in the interfacial interactions were qualitatively examined through SEM analysis of the photopolymer – PU coating interface which showed localized debonding (de-wetting) of the photopolymer when printing was performed on aged PU topcoats.

Keywords

• Additive manufacturing
• Material jetting
• Aerospace coating
• Interfacial adhesion
• Polyurethane
• Biomimetic