Design of highly anti-corrosive electroless plated Ni-P/modified halloysite nanotubes nanocomposite coating

Halloysite nanotubes (HNTs) and their modifications with either NH2 (HNT-NH2) or NH2/ Polypyrrole (HNT-NH2-PPy) were electroless-deposited into the NiP matrix for the first time to form NiP/HNT, NiP/HNT-NH2 and NiP/HNT-NH2-PPy nanocomposite coatings. The as-prepared nanocomposite coatings were heat-treated at 400 & DEG;C for 1 h. The trans-formation in microstructure, nanoindentation, Vicker's micro-hardness, surface morphology, and anti-corrosive properties of all prepared composite coatings were compared to the HNT-free (NiP) coating. Incorporating HNTs in the NiP coating made an appreciable enhancement in the hardness and corrosion resistance. Using the electro-chemical impedance spectroscopy technique (EIS), the NiP/HNT-NH2 and NiP/HNT-NH2-PPy coatings showed more significant levels of enhancement in anticorrosion perfor-mance, offering about 16.5% and 25.4%, respectively, an increase in the inhibition efficiency of unmodified one (NiP/HNT), reached to 73 and 82%. Moreover, the modified HNT coatings revealed slightly high levels of betterment in microhardness, about 9% and 5.4% for HNT modification with NH2 and NH2-PPy, respectively. In addition, the heat treatment extra improved the hardness and the corrosion resistance of all HNTs nanocomposite coatings compared to HNT-free coating. Furthermore, the heat-treated NiP/HNT has the highest protection efficiency reached to about 95%, based on the polarization measurements. This momentous improvement in the hardness and electrochemical properties reflects the ef-fect of adding the pristine and the modified HNTs into the NiP matrix, resulting in the development of high-performance NiP/HNT-NH2 and NiP/HNT-NH2-PPy composite coat-ings facilitating their use in various industries. & COPY; 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).