The purpose of this study is to clarify that a newly developed Al-Mg-Zn series aluminum alloy casting is suitable for electroless Ni-P plating. The effects of the microstructures of the newly developed aluminum alloy casting and AC4CH casting on the plating process were examined.
With the AC4CH-T6 casting containing silicon, it was difficult to obtain a smooth surface by pretreatment process because of surface irregularity between the hard and chemically stable eutectic silicon and aluminum matrix. On the other hand, with the developed silicon-free alloy casting, it was possible to produce a smooth surface by pretreatment process, and this glossiness was superior to that of the AC4CH-T6 casting after plating. Furthermore, the plating ability of the developed casting was also superior to that of the AC4CH-T6 casting, because the zinc deposit on the developed casting from the zincate treatment became uniform due to uniform displacement reaction.
The glossiness of the developed casting treated with electropolishing as a pretreatment process covered with electroless Ni-P plating was the same as that of the AC4CH-T6 casting covered with decorative chrome electroplating.
