Bioinspired self-healing nickel coating

Abstract

We present a study of self-healing mechanisms including their kinetics and thermodynamics in nickel coatings. The bioinspired self-healing coating is designed to enhance the durability of structural metal components exposed to harsh conditions. Microcapsules, reminiscent of natural healing reservoirs, were synthesized via in situ polymerization in an oil-in-water emulsion to encapsulate linseed oil, a healing agent, within poly(urea-formaldehyde) (PUF) shells. Nickel coatings incorporating PUF shell microcapsules were electrodeposited on mild steel substrates to assess their effectiveness in self-healing, mimicking nature's ability to provide on-demand healing. Comprehensive characterization of the microcapsules and coating was performed using techniques including Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Thermogravimetric Analysis (TGA). The self-healing performance of the coating was evaluated using SEM and EDS after scratches simulating damage were made on the surfaces of the samples. Corrosion resistance and self-healing ability were evaluated through an immersion test, and additional corrosion resistance tests such as Open Circuit Potential (OCP) and Linear Polarization (LP) were conducted. The results indicate that the nickel coating containing PUF shell microcapsules confers corrosion resistance to the substrate and, upon damage to that coating, induces a self-healing response analogous to natural systems, highlighting the potential of bioinspired designs in advanced material solutions.