A Nickel Dissolution Process for Multilayer Electroforming to Achieve Ultrahigh Adhesion Strength

Area of Science:

• Materials Science
• Electrochemistry
• Surface Engineering

Background:

• Multilayer electroforming offers potential for producing high-quality Ni/Ni structured metal walls.
• Nickel's susceptibility to oxidation in air leads to poor adhesion between layers, limiting applications.

Purpose of the Study:

• To develop and evaluate a novel in situ treatment for improving adhesion between electroformed Ni layers.
• To address the challenge of low interlayer adhesion caused by nickel oxidation.

Main Methods:

• A three-step in situ treatment involving electrochemical dissolution, surface protection, and electroforming was employed.
• Polarization behavior studies determined optimal conditions for oxide removal and surface activation in NH2SO3H solution.
• Characterization of adhesion strength using normal and shear tests.

Main Results:

• Electrochemical dissolution effectively removed the oxide film from the Ni layer at a current density of 5 A·cm⁻².
• Surface activation and protection were achieved at 8 A·cm⁻², resulting in a smooth, hydrophilic substrate.
• Ultrahigh normal and shear adhesion strengths exceeding 400 MPa between Ni layers were successfully obtained.

Conclusions:

• The proposed in situ treatment significantly enhances interlayer adhesion in multilayer Ni electroforming.
• This method overcomes the limitations of Ni oxidation, enabling the production of robust Ni/Ni layered structures.
• The achieved adhesion strengths pave the way for advanced applications requiring high-performance metal walls.