Optimization of electroless Ni B-nanodiamond coating corrosion resistance and understanding the nanodiamonds role on pitting corrosion behavior using shot noise theory and molecular dynamic simulation

Abstract

This study aimed to optimize the corrosion resistance of the electroless NiB-nanodiamond coating using a response surface method (RSM) by changing the electroless bath parameters and understand the role of nanodiamonds on pitting corrosion behavior using linear polarization, and electrochemical noise measurements as well as molecular dynamics simulation. The structure of optimized coating and nanodiamonds (ND) were characterized using FTIR, XPS, GDOES, SEM, and TEM. The stability of nanodiamonds was improved through acid treatment in HNO3 and H2SO4 (volumetric 1:3) solution. The quadratic model for predicting the polarization resistance of coatings based on the designed experiments was proposed with an accuracy of 92.85 %. Calculation of the pit initiation rate based on Weibull probability plots and probability of non-exceedance of pit diameter from shot noise theory reveals that the pit nuclei form at almost the same rate for NiB and NiB-nanodiamond coating, however, in NiB-nanodiamond coating the growth of pits is stopped. The molecular dynamic simulation showed that chloride ions forms weak chemical bonding on the ND surface than nickel due to the lower adsorption energy between the nanodiamonds surface and chloride ions which block localized corrosion attack.