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Electrochemical Surface Structuring for Strong SMA Wire-Polymer Interface Adhesion.
Anna Gapeeva1, Julia Vogtmann2, Berit Zeller-Plumhoff3
1Functional Nanomaterials, Institute for Materials Science, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143 Kiel, Germany.
ACS Applied Materials & Interfaces
|April 30, 2021
Summary
Structuring shape memory alloy (SMA) wires via electrochemical etching significantly enhances their adhesion strength in active hybrid composites by over 3 times. This surface modification improves mechanical interlocking without compromising the SMA wire
Area of Science:
- Materials Science
- Composite Materials
- Smart Materials
Background:
- Active hybrid composites utilize shape memory alloy (SMA) wires for morphing surfaces in aerospace and automotive applications.
- Adhesion strength between SMA wires and polymer matrices is critical for load transfer and composite functionality.
- Optimizing the SMA-polymer interface is key to enhancing composite performance and actuation potential.
Purpose of the Study:
- To improve the interface adhesion strength of shape memory alloy (SMA) wires within active hybrid composites.
- To investigate the effect of surface structuring on the mechanical and actuation properties of SMA wires.
- To explore the relationship between surface morphology and failure modes in SMA-polymer interfaces.
Main Methods:
- Commercially available NiTi SMA wires (1 mm diameter) were surface-structured using selective electrochemical etching.
- Etching targeted defect sites, preserving thermodynamically stable surfaces and creating etch pits.
- Pull-out tests with optical stress measurement and actuation characterization were performed on structured and as-delivered wires.
Main Results:
- Surface structuring increased the force of first failure by over 3 times compared to as-delivered SMA wires.
- Structured wires exhibited enhanced surface area and mechanical interlocking, leading to mixed adhesive/cohesive failure modes.
- Actuation tests showed comparable work capacity, and mechanical/thermal properties (stress-strain curve, transformation temperatures) remained unaffected.
Conclusions:
- Selective electrochemical etching is an effective method to significantly enhance SMA wire adhesion in hybrid composites.
- Surface structuring improves mechanical interlocking and load transfer without negatively impacting SMA wire functionality or performance.
- This approach offers a promising strategy for developing advanced morphing surfaces with improved durability and actuation capabilities.
