Influence of nickel recovery efficiency on crystallinity and microhardness of electroless Ni–P coatings and optimisation using Taguchi technique

Abstract

This research paper reports on the improvement of nickel recovery efficiency (NRE) and microhardness of the electroless Ni–P coating process. At present, in the electroless nickel coating process, the NRE is very low. Owing to this reason, the coating cost of electroless nickel is very high. Earlier researchers have tried to recover the nickel from the used bath after coating is completed and some achieved success in their attempt by further improving the nickel recovery from 25 to 35%. To overcome the above problem, the excess amount of reducing agent (RA) is supplied to the bath during the coating process to compensate for the consumed amount of electrons. The influence of adding excess amount of RA on NRE and other properties of the deposit have been investigated in this study. The NRE was significantly increased from 35 to 61%.The various coatings parameters used in the electroless bath were optimised to get the high NRE using a Taguchi optimisation technique.

Keywords:

• Electroless plating
• Nickel recovery efficiency
• Excess reducing agent
• Crystallinity
• Microhardness
• Optimisation