Application of Nickel Deposition on Electropolishing (EP), Chempolishing (CP), and As-Built Additively Manufactured (AM) Metal Components

Abstract

Existing additive manufacturing (AM) technologies produce metal components with a rough surface that generally display fatigue characteristics, leading to component failure and undesirable friction coefficients to the printed part. Small cracks formed at regions of high surface roughness in rough surfaces act as a stress raiser or crack nucleation site. Hence, as-produced parts’ direct use is limited and introduces a challenge related to smoothening the surface. The present study explores the application of electroless nickel deposition. It examines the surface finishing techniques such as Chempolishing (CP) and Electropolishing (EP) for post-processing on additively manufactured stainless-steel samples. Previous studies have demonstrated that CP offers a major advantage in providing consistent, smooth surfaces, regardless of the component size or geometry. Surface smoothness is increased, and surface roughness is decreased to the sub-micrometer range via EP. The study also investigates nickel deposition on EP, CP, and as-built AM components, utilizing electroless nickel solutions. Alloys are exposed to an electroless nickel plating process in order to enhance the hardness and surface resistance of produced components to the hostile environment. The medium-phosphorus (6–9% P), and high-phosphorus (10–13% P) was used. The Ni deposition experiments were optimized using the L9 Taguchi design of experiments (DOE), which involve the prosperous content in the solution, surface preparation, plane orientation of the sample geometry, and Nickel strike exposition time. The pre- and post-processed surface of the AM parts is being investigated by the KEYENCE Digital Microscope VHX-7000. This work is in progress concerning the complete Scratch analysis and Design of Experiment (DOE) analysis using the Qualitek-4 software.