Pulse electrodeposition and characterization of Ni-Si3N4 composite coatings

Abstract

Ni-Si3N4 nano-composite coatings were prepared by pulse current (PC) electrodeposition and direct current (DC) electrodeposition techniques. The micro-structure of the coatings was characterized by scanning electron microscopy (SEM), vickers microhardness, X-Ray Diffraction (XRD) and wear-friction tests. The results showed that the micro-structure and wear performance of the coatings were affected by the electrodeposition techniques. Pulse current electrodeposited Ni-Si3N4 composite coatings exhibited higher microhardness, smooth surface, and better wear resistance properties as compared to coatings prepared under DC condition. The Ni-Si3N4 composite coatings prepared at 50 Hz pulse frequency with 10 % duty cycles has shown higher codeposition of nano-particles. Consequently, increased microhardness and less plastic deformations occurred in coatings during sliding wear test. The XRD patterns revealed that the increased pulse frequencies changed the preferred (100) nickel crystallite orientations into mixed (111) and (100) orientations.