Use of a 3D printed auxiliary module for the quality improvement of Ni-P/SiC nanocomposite coatings

Ni-P/SiC composite electroplated coatings are considered as one of the most cost-effective and best-performing combinations that could replace hard chromium coatings, due to their excellent microhardness, as well as wear and corrosion resistance. These properties depend, among others, on the phosphorus content of the Ni-P matrix and the amount, distribution and particle size of the embedded SiC nanoparticles (NPs) [1].

Ni-P/SiC coatings can be divided in three main categories: low (1-5%), medium (5-8%) and high phosphorous content (above 9%) [2]. Pillai et al. observed that the incorporation of phosphorous in the nickel lattice can reduce the nickel grain size from microns to nanometers [3]. In addition, the utilization of pulse current electroplating has been shown to improve the quality and the properties of the Ni-P/SiC coatings [4, 5]. The electroplating process also depends on other factors such as the design and actual set-up of the electroplating cell, the hydrodynamic conditions and the positioning and geometrical characteristics of the anode and the cathode.

In this work, the modification of the electrolytic cell set up by designing and printing a plastic auxiliary module, made by ABS with the aid of a Fused Filament 3D printer, is presented. This module was installed in the bath to alter the hydrodynamic conditions in the area of the cathode. The effect of the current density and the duty cycle on the pulse current Ni-P/SiC electrodeposition was subsequently investigated.

The properties of the produced coatings were evaluated by optical microscopy and Vickers microhardness measurements. The Si content was determined with a portable XRF analyzer. Moreover, DLS measurements were also performed to investigate the SiC particle size during the plating process. Our results show that the introduction of the 3D printed auxiliary module resulted in a more uniform and dense co-deposition of SiC NPs in the Ni-P matrix which in turn led to a substantial enhancement of the Vickers microhardness of the produced Ni-P/SiC nanocomposite coatings.