Electroless Ni–B–MMT nanocomposite on magnesium alloy

Abstract

Ni–B and Montmorillonite (MMT)-containing Ni–B deposits were electrolessly plated on AM60B magnesium alloy. The Ni–B coating showed cauliflower-like micromorphology, microcrystalline-amorphous microstructure, and thickness of about 15 μm, which was not influenced by the inclusion of MMT nanoparticles. The surface roughness of the Ni–B coating changed from about 376 to 328 nm after the inclusion of MMT. The boron content of the electroless deposit was mildly increased after MMT inclusion. Thermal shock and porosity examinations revealed suitable adhesion and pore-free structure of the coatings, respectively. Polarization resistance of the Ni–B deposit in 3.5 wt-% sodium chloride was increased about 1.5 times by MMT inclusion. The corrosion current of the substrate was remarkably diminished from 46.89 to 0.12 µA cm⁻² by the Ni–B plating. Also, MMT incorporation causes to further decrement of the corrosion current to about 0.03 µA cm⁻².