Surface defect mitigation of additively manufactured parts using PEG enabled electroless nickel boron coatings

A. Jolly1,2, V. Vitry2, G. T. P. Azar1, A. Cobley1

1Institute for Clean Growth and Future Mobility, Coventry University, Priory St, Coventry, CV1 5FB, UK.
2Department of Metallurgy, University of Mons (UMONS), 23 Place du Parc, B-7000 Mons, Belgium.

The formation of defects 1 during the initial stages of manufacturing of ferrous alloy additively manufactured (AM) parts negatively impact their versatility and overall mechanical performance in industries ranging from aerospace engineering to medicine 2,3. Lack of fusion and gas entrapment, during the production processes, leads to increased surface roughness and porosities in the finished part. A methodology for simulating AM type defects on ferrous alloy substrates was developed in this study. The approach was influenced by the electrochemical deposition techniques used to fill vias in the electronics industry 4,5 that (to some extent) resemble the size and shape of AM type defects. This work investigated the use of polymeric surfactant PEG to attenuate surface roughness 6 in electroless Nickel coatings thereby achieving preferential inhibition of the coating thickness on the surface and promoting the filling of the simulated defects. It was found that the use of electroless Ni-B to fill simulated defects on ferrous alloy based materials was strongly influenced by the concentration and nature of the surfactant molecule. The results indicated that surfactant enabled electroless Ni-B deposition could be a facile approach to filling defects in ferrous based AM parts. 


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