Influence of ultrasonic power on microstructure and performance of electroless deposited Ni-W-SiC nanocoatings

Abstract

This study reports the deposition of Ni-W-SiC nanocoatings on the 45-steel using the ultrasound-assisted electroless deposition (UELD) technique. The hardness and corrosion resistance of the nanocoatings were evaluated through microhardness tests and electrochemical analyses. The surface, cross-section, phase composition, and abrasion morphologies of the coatings were studied using scanning electron microscopy and X-ray diffraction. The findings indicated that the Ni-W-SiC coating obtained at 200 W showed a compact, fine, and flat microstructure with a porosity of only 0.03 %. As the ultrasonic power during the UELD process increased from 0 W to 200 W, the SiC content in the coating rose from 2.77 to 4.16 wt% The maximum bonding force of the coating synthesized without ultrasound was approximately 89.8 N. However, the bonding force of the coatings significantly decreased with increasing ultrasonic power. The coating’s thickness also increased, from 11.09 μm at 0 W to 14.97 μm at 300 W. At 200 W ultrasonic power, the diffraction peaks of the coating were both the lowest and broadest among all the coatings. Further, the coating achieved the highest microhardness value of 676 HV. At 200 W ultrasonic power, the coating's corrosion current density was 1.63×10−7 A/cm2, which is only one-twelfth that of 45 steel, demonstrating exceptional corrosion resistance. The electrochemical impedance spectroscopy (EIS) testings indicated that an excellent corrosion resistance of Ni-W-SiC coating was deposited by using a 200 W ultrasonic power. This study provides a technical support for the preparation of nickel-based composite coatings.