Study on mechanical and corrosion resistance of Ni-W-P composite coating reinforced by cationic cubic boron nitride

Abstract

In this paper, the oxidative self-polymerization and ionization reactions of dopamine were used to modify the surface of nanoparticle cBN to obtain a cationic nanoparticle DRcBN+, which was co-deposited with Ni-W-P alloy by pulse electrodeposition technology to create a novel Ni-W-P based composite coating. A stronger adsorption force between the cathode and DRcBN+ under the influence of the electric field results from the presence of -NH3+ on the surface of DRcBN+, which prevents structural flaws in the coating brought on by cBN's lack of adsorption force during the process from cathode adsorption to deposition. The research results show that DRcBN+ is embedded in the Ni-W-P alloy coating, which reduces the coating's crystallite size, improves its compactness and microhardness, and enhances its wear resistance and corrosion resistance. The dispersion strengthening caused by nanoparticles may be the cause of the increased microhardness and wear resistance, which is consistent with Hall-Petch theory to a certain extent. In addition, in the immersion test of 3.5 wt% NaCl solution, it was found that DRcBN+ nanoparticles could enhance the long-term corrosion resistance of Ni-W-P alloy coating. This might be because the -NH3+ on the surface of DRcBN+ can electrostatically adsorb electrons and promote the formation of passive film. In addition, the composite coating can achieve corrosion inhibition because of its adsorption of corrosive negative ions (Cl−).