POSTECH improves metal–polymer bonding in Additive Manufacturing
Researchers from the Pohang University of Science and Technology (POSTECH), South Korea, have published research in Virtual and Physical Prototyping on a Laser Beam Powder Bed Fusion (PBF-LB) technique that engineers surface roughness to improve bonding strength between additively manufactured metal parts and silicone polymers.
The study explored how process parameter adjustments could be used to control the surface roughness of metal AM parts while maintaining relative densities above 99%. Researchers produced surfaces ranging from polished finishes with an average roughness (Ra) of 2.1 µm to as-built morphologies with Ra values of 26.7 µm, 56.9 µm and 65.9 µm.
The researchers then evaluated the surfaces for metal–polymer bonding performance using lap-shear tests with EcoFlex, Dragon Skin and polydimethylsiloxane (PDMS) silicone polymers. According to the findings, the engineered roughness significantly improved adhesion strength compared to polished surfaces.
The highest bonding performance was achieved using the high-roughness condition with an Ra of 56.9 µm. Under these conditions, adhesive strengths reached 220.8 kPa for EcoFlex, 321.0 kPa for Dragon Skin and 717.2 kPa for PDMS.
Compared to untreated polished surfaces, the approach increased adhesive strength by 214.3% for EcoFlex, 228.5% for Dragon Skin and 228.7% for PDMS, the researchers reported.
The researchers also demonstrated the fabrication of multi-roughness regions within a single component, which could enable site-specific functionality in hybrid metal–polymer Additive Manufacturing machines.
The researchers concluded that their manufacturing-integrated roughness engineering strategy could provide a simplified route to producing high-performance metal–polymer joints while supporting the development of design-flexible multi-material architectures.
‘Surface roughness engineering of mechanical interlocking for enhanced metal–polymer adhesion in additive manufacturing’ is available here.
