Preparation and Performance of Silver Coated Copper Powder

摘要

Different parameters are used to characterize the conductivity of copper powder with silver plating. Ethanediamine (C_2H_8N_2) is employed to adjust the pH value of plating solution (solution A), and chelate Cu~(2+) generated by side reaction, forming sound five-membered ring structure with Cu~(2+), thus preventing the formation of Cu(NH_3)_4~(2+) which can avoid adsorption of Cu(NH_3)_4~(2+) on the surface of copper powder. In this way silver-plated copper powder with conductivity equal to fine silver powder can be obtained, the effects of dosage of C_2H_8N_2 and Tollens' reagent concentration on performance of silver-plated copper powder have also been investigated. The result shows that dosage of C_2H_8N_2 has significant effects on electrical conductivity of silver-plated copper powder. The dosage of C_2H_8N_2 should ensure that pH value of control solution A maintains 9.0~10.0. The concentration of Tollens' reagent should make sure that the generated silver-plated copper powder is most even and continuous and tightness when silver particles in form of heterogeneous nucleation is surrounded on the surface of copper powder, and the optimum concentration is 0.09 mol/L. The conductivity of silver-plated copper powder made by Tollens' reagent with 0.09 mol/L concentration is optimal, which is 3.9×10~(-4)Ω?cm, when adjusting the pH value of solution A to 9.5 by C_2H_8N_2 control.