The effect of pH on synthesizing Ni-decorated MWCNTs and its application for Sn-58Bi solder

Nickel-decorated multi-walled carbon nanotubes (Ni-MWCNTs) were synthesized using a colloidal method and an electroless plating method to form Ni nanoparticles on the surface of MWCNTs. The Ni electroless plating process was optimized with solutions at various pH (5, 6, 7, and 8) levels. The Ni-MWCNTs fabricated at pH 7 show the most stable Ni nanoparticles on the surface of the MWNCTs. After optimization of the Ni plating process, the Ni-MWCNTs/Sn-58Bi composite solder were fabricated with varying contents of (0, 0.05, 0.1 and 0.2 wt%) Ni-MWCNTs. The experimental results show that Ni-MWCNTs enhance the mechanical properties of Sn-58Bi solder. The shear strength of Sn-58Bi solder improves by about 14% with 0.1 wt% Ni-MWCNTs. Furthermore, the microstructure evolution after a high temperature storage test shows that Ni-MWCNTs have an effect on grain refining and interrupt growth of the Intermetallic compound layer. The distribution of Ni-MWCNTs could be recognized with the results of EPMA.