Enhancing Effect of Chloride Ions on the Autocatalytic Process of Ag(I) Reduction by Co(II) Complexes.

Loreta Tamašauskaitė-Tamašiūnaitė,Karolis Ratautas,Eugenijus Norkus,Ina Stankevičienė,Aldona Jagminienė,Gediminas Račiukaitis

doi:10.3390/ma13204556

Loreta Tamašauskaitė-Tamašiūnaitė, Karolis Ratautas + Show 4 more

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https://doi.org/10.3390/ma13204556

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Journal: Materials	Publication Date: Oct 14, 2020
Citations: 5	License type: CC BY 4.0

Affiliation: Center for Physical Sciences and Technology

Abstract

In this work, the possibilities of increasing the rate of electroless silver plating without a rise in the concentration of reactants or elevation of temperature were studied. The effect of halide additive, namely chloride ions, on the rate of electroless silver deposition was investigated, using conventional chemical kinetics and electrochemical techniques. It was found that the deposition rate of electroless silver increased 2–3 times in the presence of 10–20 mM of chlorides, preserving sufficient stability of the solution.

Highlights

Chemical deposition of silver layers is the oldest known electroless plating process, but nowadays, the deposition of electroless silver is less effective and convenient compared to the electroless nickel or copper plating
The kinetics of electroless silver deposition using the Co(II) complexes as reducing agents was investigated in detail
The accelerating effect of chloride ions is observed in a wide range of NH3 concentrations—in the entire practical pH range of electroless silver plating solutions of this type, beginning from pH 8.75 (0.5 M NH3 ) and concluding by the solution containing

Summary

Introduction

Chemical deposition of silver layers (silver mirror formation) is the oldest known electroless plating process, but nowadays, the deposition of electroless silver is less effective and convenient compared to the electroless nickel or copper plating. Many reducers can be used for obtaining metallic silver from. Ag(I) compounds, but generally, it is not so easy to get compact silver coatings due to the plenteous reduction of Ag(I) in the solution bulk. Unstable Ag(I)-ammonia (NH3 ) complex solutions with glucose, tartrate, formaldehyde, etc. Have been used as reducing agents in plating for many years. The thickness of the coatings obtained from such solutions is not large and typically less than 1 μm [1,2]. More effective electroless silver plating solutions have been developed using Ag(I)-cyanide complex and amine boranes [3] or hydrazine [4] as reducing agents. At 40–50 ◦ C, the deposition rate can reach 4 μm h−1 , and in the presence of stabilizers, these solutions are sufficiently stable [1,4,5]

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