Optimization of Electroless Nickel Tungsten Composite Coating on 3D-Printed ABS Substrate for Maximum Tungsten Content

Abstract

Electroless nickel phosphorous tungsten (Ni-P-W) coating is widely used to improve the wear and hardness of steel. Studies on the composite coating of plastics, and in particular, additive manufactured parts are lacking. Many applications are demanding high hardness and high-temperature stability of the 3D-printed parts. The purpose of this work is to study the electroless Ni-P-W composite coating on the digital acrylonitrile butadiene styrene (ABS) substrate, 3D printed by polyjet technology. Scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and X-ray diffraction analysis (XRD) are used to study structural morphology, composition, and phase structure of the coating, respectively. Electroless Ni-P-W coating on digital ABS-printed parts was successfully carried and optimized for maximum tungsten content in the coating. Finally the thermal stabilities of developed coating are compared with electroless nickel coating. The study revealed that the low level of pH and sodium tungstate in the bath results in the maximum percentage of tungsten in the coating with higher hardness. SEM and EDX analyses show a smooth crack-free surface with 4.77 wt.% of tungsten in the coating, respectively. XRD studies of the coating show amorphous nature of the coating at low pH with maximum tungsten content while at high pH, the tungsten content reduces, and the coating becomes crystalline. The developed electroless nickel tungsten composite coating with higher thermal stability can enhance the use of 3D-printed ABS parts in many applications like rapid tooling for injection moulding, electric discharge machine (EDM) tooling and electronic industries for electromagnetic shielding.