Cyanide-free composite electroplating method for plating RE-TiO2-Ag layer on surface of steel substrate

Abstract

The invention provides a cyanide-free composite electroplating method for plating a RE-TiO2-Ag layer on the surface of a steel substrate. RE rare earth element is selected from La<3+>, Pr<3+>, Gd<3+> or Yb<3+>, and titanium oxide is from titanium oxide powder with the size of 20-100nm or a titanium oxide sol solution. The electroplating method is safe and environment-friendly, the preparation process is simple, and an obtained electroplated layer is uniform, compact, strong in corrosion resistance and strong in oxidation resistance and has relatively good antibacterial and bactericidal properties.

Description

technical field [0001] The invention belongs to the technical field of electrochemical composite silver plating, and in particular relates to a novel cyanide-free silver plating solution and an electroplating process. Background technique [0002] Silver is a malleable and malleable metal with white light. It has excellent thermal conductivity and electrical conductivity. It is very stable in lye and some organic acids, and its price is relatively cheap compared with other precious metals. Therefore, silver plating on metal and non-metal surfaces has been widely used in many fields such as decorations, tableware, medical equipment and electronic products. Silver plating first began in 1800 and was proposed by the Elkington brothers in Birmingham, England. The electroplating solution used It is an alkaline cyanide system. Because cyanide has a very high complexation coefficient, the electroplating solution of the cyanide silver plating system is extremely stable, and the obta...

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Problems solved by technology

Therefore, silver plating on metal and non-metal surfaces has been widely used in many fields such as decorations, tableware, medical equipment and electronic products. Silver plating first began in 1800 and was proposed by the Elkington brothers in Birmingham, England. The electroplating solution used It is an alkaline cyanide system. Because cyanide has a very high complexation coefficient, the electroplating solution of the cyanide silver plating system is extremely stable, and the obtained coating is uniform and compact. The electroplating process is simple and the cost is low. However, as people With the continuous improvement of environmental awareness, people urgently need to develop a mature cyanide-free silver plating process to replace the heavily polluting cyanide silver plating. This is also the mainstream direction of future development. At present, cyanide-free silver plating mainly faces the following problems: ( 1) The performance of the coating cannot meet the process requirements, especially the engineering silver plating, which has more requirements than the decorative silver plating. For example, the crystallization of the coating is not as fine and smooth as cyanide, or the purity of the coating is not enough, and there are organic inclusions in the coating, resulting in hardness Too high, decreased electrical conductivity, etc., as well as decreased soldering performance; (2) The current density is small and the electrodeposition speed is slow, so it cannot be used for thick silver plating, let alone high-speed silver plating; (3) The plating solution is stable Whether it is alkaline bath, acidic bath or neutral bath, there are different degrees of bath stability problems, which brings inconvenience to management and operation

At the same time, the cost has increased; (4) cyanide-free silver plating often has poor dispersion ability and low cathode current density

[0003] Silver compounds or silver ions have the ability to kill or inhibit the reproduction of bacteria, viruses, algae and fungi, while titanium dioxide has a strong photocatalytic performance. Anatase titanium oxide can decompose harmful formaldehyde for 30 hours under natural light for 8 hours. %, and under ultraviolet light, it can effectively degrade and eliminate organic pollutants, so it is widely used in wastewater treatment and environmental protection. For titanium oxide sterilization, Professor Teng Daozhao of the Faculty of Engineering of the University of Tokyo proved that TiO 2 It has a strong bactericidal ability to Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus, so there are also a lot of researches on Ag-TiO 2 Coated medical devices, but the bonding force and coating effect are poor

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