Aluminum, a kind of amphoteric metals, and its alloys have a high affinity for oxygen to form amphoteric oxides or hydroxides. This means that clean, bare aluminum forms an oxide film rapidly. It is difficult to plate onto an oxide film with good adhesion. However, to electroless nickel (EN) plate onto aluminum alloys successfully with good adhesion, the oxide film must be removed and Zinc-immersion (chemical replacement) process is required. Our zinc-replacement agent was developed for pretreatment of EN or any other plate on aluminum and its alloys. The chemical mechanisms of the zinc-replaced aluminum are shown as below:

 

    Al2O3＋2NaOH --> 2NaAlO2＋H2O

    2Al＋2NaOH --> 2NaAlO2＋3H2

    2Al＋3ZnO2－2＋2H2O --> 3Zn＋2AlO2－＋4OH－ 

 

Plating on aluminum substrates is more complex than that of copper and iron. Zinc replacement process produce a kin on clean, deoxidized aluminum and protect the aluminum from oxidation. The advantages of our zinc-replacement agent are:

1) Real to use

2) Easy to operate

3) Easy to manage and maintain