Particle-Size-Dependent Anticorrosion Performance of the Si3N4-Nanoparticle-Incorporated Electroless Ni-P Coating

Electroless Nickel-Phosphorus (Ni-P) coating is recognized mostly for its outstanding corrosion and wear-resistant behavior. The intrinsic corrosion and wear-resistant properties of Ni-P-based coating could be further upgraded by incorporating appropriate second-phase additive particles into the coating matrix. However, such properties of the Ni-P-based coating greatly rely on the surface and microstructural evolution arising with the co-deposition of the additive particles. In this study, submicron Si3N4 (average size ~200 nm) and nano Si3N4 (average size ~20 nm) particles were incorporated while depositing a Ni-P alloy in a low-carbon steel substrate to develop the Ni-P-Si3N4 composites through the electroless coating method. The 20 nm Si3N4-incorporated composite coating constituted fewer defects such as cavities and micropores on the surface, but such defects significantly appeared on the surface of the composite after the incorporation of 200 nm Si3N4 nanoparticles. Subsequently, the composite Ni-P-Si3N4, developed with the co-deposition of 20 nm nanoparticles, is enriched with enhanced anticorrosion characteristics compared with the composite developed with 200 nm nanoparticles. The enhancement of anticorrosion behavior was attributed mainly to the Si3N4 nanoparticles that covered the substantial volume of the coating and led to inhibit the formation of corrosion active sites such as defects and metallic Ni phase.

Automated summary

In this study, Ni-P-Si3N4 composite coatings were developed on a low-carbon steel substrate using electroless coating method. Incorporating 20 nm Si3N4 particles in the coating resulted in fewer surface defects, while the addition of 200 nm Si3N4 particles led to significant defects on the surface of the composite. The Ni-P-Si3N4 composite developed with 20 nm nanoparticles exhibited enhanced anticorrosion characteristics compared to the composite developed with 200 nm nanoparticles.