Influence of titanium dioxide nanopowder addition on microstructural development and hardness of tin–lead solder

This paper presents the microstructure and hardness of composite solders obtained by the addition of nanopowders of titanium dioxide to a conventional solder. Titanium dioxide powders-reinforced lead (Pb)–tin (Sn) composite solders were prepared by thoroughly blending nano-sized titanium dioxide powders with powders of a eutectic solder and using a water-soluble flux. The blended solder paste was melted and allowed to re-solidify in a crucible placed on a hot plate and maintained at a constant temperature. Optical microscopy observations revealed that for additions of titanium dioxide up to 1 wt.%, the grain size and width of the grain boundary decreased. For the addition of 2 wt.% of titanium dioxide, nanopowders microporosity was observed both at and along the grain boundary regions coupled with the presence of second-phase particles. Microhardness measurements revealed that the addition of titanium dioxide nanopowders is helpful in enhancing the overall strength of the eutectic solder.