Research On Complex Agents Selection Used In Cu-Ni Alloy Plating

Owing to its nice surface performance, Cu-Ni alloy is a kind of excellent material for coinage. Furthermore, Cu-Ni alloy plating has wide application prospect due to its advantageous price and false-proof characteristics. However, the electric potential difference between copper( II) and nickel( II) is 0.6v, and owing to their other similar characteristics, the complexation properties of most complex agents with copper( II) and nickel( II) are nearly the same. Therefore, the key to realize simultaneous codeposition of copper and nickel is to discover the suitable complex agent and ascertain its working conditions.By the research on the complexation properties and structure, the author did lots of experiments and screened several complex agents. This paper focuses on the optimizing experiments which use citric acid, triethanolamine, and NB01 as main formulation. The results show that, using citric acid as the main formulation can get low-nickel content alloy coatings, but it is diffcult to furtherly increase its nickel content; the triethanolamine formulation will bring into being positve charge, which is not farourable for cathodic polarization, besides, it will produce plenty of copper powder, which is not fit for industrial production either; the NB01 formulation with some citric acid can come into being about 25% Cu-ni alloy coatings, consequently, this formulation has the prospect to be furtherly developed.The choice of auxiliary complex agents in this paper take various factors into account, such as, space factor, charge factor, application of feasibility of getting copper( I), and complementarity between the main and auxiliary complex agents etc. Complex agents , auxiliary complex agents and electropositive hydroniums come into multicomplexes. Then,multicomplexes come into being. By experiment, the stability of multicomplexes and auxiliary complexes' comprehensive influence on alloy coatings are ascertained. Ajusting metal ion concentration, content of main and auxiliary complex agents, pH etc., We ascertain the basic formulation.This paper mainly studied the influence of the additives on alloy coatings in the meathod of using NB01 as the main formulation. And by experimenting on the parameters of temperature of electrolyte, electric currunt density, rotational speed of barrel and so on, we eventually ascertain the plating technological conditions.