Effects of NH4F on the deposition rate and buffering capability of electroless Ni–P plating solution

The deposition rate and buffering capability of alkaline electroless Ni–P plating solution containing ammonium fluoride (NH4F) have been investigated. When the NH4F concentration is below 10 g L− 1, the deposition rate is improved with the addition of NH4F, reaching the maximum value at 2 g L− 1. The buffering capability of solutions is found to be improved with increasing NH4F concentration. Due to the improvement of buffering capability, refined and compact Ni–P coatings with homogeneous elemental distribution of P have been achieved. Therefore, both the corrosion resistance and microhardness of Ni–P coatings are significantly improved. The mechanism of NH4F improving the deposition rate and the buffering capability is discussed.